Co-reporter:Wen Ren, Shaojun Guo, Shaojun Dong, and Erkang Wang
The Journal of Physical Chemistry C June 2, 2011 Volume 115(Issue 21) pp:10315-10320
Publication Date(Web):May 5, 2011
DOI:10.1021/jp110532c
Herein we developed a simple and low-cost route for morphology-controllable synthesis of Ag dendrites based on a facile wet chemical route. The morphology of Ag dendrites was tunable by changing the concentration of capping reagent PVP. It was demonstrated that for higher concentrations of PVP, smaller Ag dendrites with shorter and smoother branches were obtained, while the ratio of the length of the branches to the body diameter of the Ag dendrites (L/D) became lower. It was also shown that the concentration of added AgNO3 was very important for the formation of Ag dendrites. The presented method is amenable for extension to large-scale synthesis of Ag dendrites. The prepared Ag dendrites exhibited strong near-infrared absorption proved by UV–visible spectra. Using p-ATP as a probe molecule, the SERS activity of prepared Ag dendrites was estimated. Based on the apparent enhancement factor and the measured diameter and L/D of the morphology-controlled Ag dendrites, the relation between the morphology and the SERS activity of Ag dendrites was investigated. It was shown that the smaller Ag dendrites with a lower L/D exhibited larger SERS activity.
Co-reporter:Hailong Li;Shaojun Guo;Qinghui Liu;Lidong Qin;Shaojun Dong;Yaqing Liu
Advanced Science 2015 Volume 2( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/advs.201500054
Co-reporter:Jiyang Liu, Tianshu Wang, Jin Wang, Erkang Wang
Electrochimica Acta 2015 Volume 161() pp:17-22
Publication Date(Web):10 April 2015
DOI:10.1016/j.electacta.2015.02.034
•Outstanding 3D biosensing platform was explored for reagentless detection of H2O2.•Monolithic 3D graphene foam served as a freestanding electrode scaffold.•MB-CNTs hybrid assembled on 3D graphene as efficient electron mediator.•Mussel inspired polydopamine as a green linker for enzyme immobilization.A simple and versatile method is described to construct high performance three-dimensional (3D) graphene-based enzyme biosensor. Monolithic and macroporous 3D graphene foam grown by chemical vapor deposition (CVD) was used as a freestanding electrode for co-immobilization of horseradish peroxidase (HRP) and a commonly used redox mediator, methylene blue (MB). Carbon nanotubes (CNTs) were employed as carriers of MB molecules to immobilize them on 3D graphene surface through strong π-π stacking force. Mussel-inspired biopolymer polydopamine (PDA) was formed by in-situ polymerization and served as a green linker, which could covalently graft HRP on the surface of 3D graphene/MB-CNTs electrode. In addition, PDA layer could also effectively prevent the leakage of inner electron mediators. Owing to the 3D macroporous architecture, exceptional properties of graphene and surface-bound mediators, the biosensor demonstrated outstanding performance for reagentless detection of H2O2 in terms of wide linear range (0.2 μM to 1.1 mM), high sensitivity (227.8 μA mM−1 cm−2), low detection limit (58.0 nM), and fast response (reaching 95% of the steady current within 3 s). The biosensor exhibited high reproducibility and stability.
Co-reporter:Tianshu Wang, Jiyang Liu, Xiaoxiao Gu, Dan Li, Jin Wang, Erkang Wang
Analytica Chimica Acta 2015 Volume 882() pp:32-37
Publication Date(Web):2 July 2015
DOI:10.1016/j.aca.2015.05.008
•Fc-PAH was modified on the surface of graphene to prepare hybid nanocomposite (Fc-PAH-G).•A cytosensor was constructed with Fc-PAH-G, PSS and aptamer AS1411 by LBL technology.•The sensing interface introduced more redox probe and enhanced current signal on electrode.•The sensor showed a detection range of 10–106 cells/mL with a detection limit of 10 cells/mL.Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 106 cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells.
Co-reporter:Tianshu Wang, Jiyang Liu, Jiangtao Ren, Jin Wang, Erkang Wang
Talanta 2015 Volume 143() pp:438-441
Publication Date(Web):1 October 2015
DOI:10.1016/j.talanta.2015.05.022
•Phospholipids-AuNPs-graphene biocomposite (PLs-AuNPs-G) was prepared.•PLs-AuNPs-G was demonstrated as an effective matrix for MP-11 immobilization.•A third generation biosensor based on PLs-AuNPs-G was constructed for H2O2 detection.•The biosensor exhibited high sensitivity and good stability.•The biosensor realized real-time detection of H2O2 released from living cells.A hybrid composite constructed of phospholipids bilayer membrane, gold nanoparticles and graphene was prepared and used as matrices for microperoxidase-11 (MP11) immobilization. The direct electrochemistry and corresponding bioelectrocatalysis of the enzyme electrode was further investigated. Phospholipid bilayer membrane protected gold nanoparticles (AuNPs) were assembled on polyelectrolyte functionalized graphene sheets through electrostatic attraction to form a hybrid bionanocomposite. Owing to the biocompatible microenvironment provided by the mimetic biomembrane, microperoxidase-11 entrapped in this matrix well retained its native structure and exhibited high bioactivity. Moreover, the AuNPs–graphene assemblies could efficiently promote the direct electron transfer between the immobilized MP11 and the substrate electrode. The as-prepared enzyme electrode presented good direct electrochemistry and electrocatalytic responses to the reduction of hydrogen peroxide (H2O2). The resulting H2O2 biosensor showed a wide linear range (2.0×10−5–2.8×10−4 M), a low detection limit (2.6×10−6 M), good reproducibility and stability. Furthermore, this sensor was used for real-time detection of H2O2 dynamically released from the tumor cells MCF-7 in response to a pro-inflammatory stimulant.A hybrid composite constructed of phospholipids bilayer membrane, gold nanoparticles and graphene was prepared and used as matrices for microperoxidase-11 (MP11) immobilization. The composites promoted the direct electron transfer between MP11 and the underlying electrode. Moreover, the biosensor successfully realized the detection of H2O2 releasing from cancer cells.
Co-reporter:Siqi Zhang, Amin Bao, Ting Sun, Erkang Wang, Jiahai Wang
Biosensors and Bioelectronics 2015 Volume 63() pp:287-293
Publication Date(Web):15 January 2015
DOI:10.1016/j.bios.2014.07.062
•A new sensing paradigm based on nanopore for ATP was proposed.•Combination of SWNTs and nanopore for constructing sensor was accomplished.•The study evades the immobilization of target-specific probe onto nanopore surface.•The aptamer–ATP complexes can be quantitated by nanopore coated with PEI/Zr4+.By virtue of a biomimetic nanopore and single-walled carbon nanotubes, a new sensor for adenosine triphosphate (ATP) detection is designed. As compared to the routine approach, the present scenario does not entail the surface modification of nanopore with analyte-specific probes. The underlying mechanism relies on a symmetric nanopore sequentially modified with polyethyleneimine (PEI) and Zr4+ that can quantitate the concentration of ATP-bound aptamer, while other free aptamers are removed by single-walled carbon nanotubes (SWNTs). The detection limit of the nanopore sensor is 27.46 nM, and the linear range is from 50 nM to 400 nM. The biosensor with an excellent selectivity against guanosine triphosphate (GTP), uridine triphosphate (UTP), and cytosine triphosphate (CTP) can be applied in the real samples such as Hela cell.Without the interference from free target-specific probes that can be eliminated by SWNTs, PET/Zr4+ coated nanopore that is responsive to the ATP-bound aptamer can quantitatively detect ATP concentration. In contrast to previous studies based on nanopore, this study evades the immobilization of target-specific probe onto the nanopore surface.
Co-reporter:Qiao Cao, Ye Teng, Xuan Yang, Jin Wang, Erkang Wang
Biosensors and Bioelectronics 2015 Volume 74() pp:318-321
Publication Date(Web):15 December 2015
DOI:10.1016/j.bios.2015.06.044
•A label-free biosensor based on enhanced fluorescent Ag NCs are developed for DNA detection.•We choose three disease-related genes that are HIV, HBV and HTLV-I gene as our detected target.•The method has a detection limit as low as nanomolar.•The method can distinguish one nucleotide mismatched target.In this paper, we developed a simple, low-cost and sensitive DNA sequences detection biosensor based on a label-free molecular beacon (MB) whose DNA hairpin structure terminal has a guanine-rich sequence that can enhance fluorescence of silver nanoclusters (Ag NCs). Without hybridization between hairpin probe and target DNA, the Ag NCs presented bright fluorescence for the proximity of guanine-rich sequences (GRSs). After binding with target DNA, the hairpin shape was destroyed which results in a decrease of the Ag NCs fluorescence intensity. With this biosensor, we detected three disease-related genes that were the human immunodeficiency virus (HIV) gene, hepatitis B virus (HBV) gene and human T-lymphotropic virus type I (HTLV-I) gene. The detection limits based on S/N of 3 were 4.4 nM, 6.8 nM and 8.5 nM for HIV gene, HBV gene and HTLV-I gene, respectively. Our sensor was also of high selectivity and could distinguish even one nucleotide mismatched target.
Co-reporter:Jiyang Liu, Jiao Wang, Tianshu Wang, Dan Li, Fengna Xi, Jin Wang, Erkang Wang
Biosensors and Bioelectronics 2015 Volume 65() pp:281-286
Publication Date(Web):15 March 2015
DOI:10.1016/j.bios.2014.10.016
•Immunosensor based on monolithic 3D graphene was prepared for the first time.•3D graphene was functionalized by in-situ polymerization of dopamine.•Polydopamine layer imparts 3D graphene with well hydrophilicity and modifiability.•Lectin grafted on polydopamine was used to immobilize sugar-protein labeled Ab.•A wide detection range of 0.1–750.0 ng ml−1 was reached.A high performance three-dimensional (3D) electrochemical immunosensor was developed for sensitive detection of the tumor biomarker, carcinoembryonic antigen (CEA). Monolithic and macroporous graphene foam grown by chemical vapor deposition (CVD) served as the scaffold of the free-standing 3D electrode. Immuno-recognition interface was fabricated via simple and non-covalent immobilization of antibody using lectin-mediated strategy. Briefly, the well-known lectin macromolecule (concanavalin A, Con A) monolayer was functionalized on 3D graphene (3D-G) using in-situ polymerized polydopamine as the linker. Then the widely used horseradish peroxidase (HRP)-labeled antibody (anti-CEA) in immunoassays was efficiently immobilized to demonstrate the recognition interface via the biospecific affinity of lectin with sugarprotein. The 3D immunosensor is able to detect CEA with a wide linear range (0.1–750.0 ng ml−1), low detection limit (~90 pg ml−1 at a signal-to-noise ratio of 3), and short incubation time (30 min). Furthermore, this biosensor was used for the detection of the CEA level in real serum samples.
Co-reporter:Qingfeng Zhai, Siqi Zhang, Hong Jiang, Qin Wei, Erkang Wang and Jiahai Wang
Journal of Materials Chemistry A 2014 vol. 2(Issue 37) pp:6371-6377
Publication Date(Web):23 Jul 2014
DOI:10.1039/C4TB00844H
In this article, we propose a new method for selective detection of Hg2+ based on a biomimetic nanopore sensing platform in combination with single-walled carbon nanotubes (SWNTs). As is well known, folded DNA in the presence of Hg2+ can be separated from single-stranded DNA through SWNTs, and the folded DNA can be quantitated with cone-shaped nanopore whose surface was coated by polyethyleneimine (PEI)/Zr4+. Both sensitivity and selectivity based on this paradigm can be guaranteed without immobilization of probes on the nanopore surface. This approach can warrant the detection limit for Hg2+ down to 8.3 nM (S/N = 3) with high selectivity against other metal ions. Moreover, the application of the sensor for lake water shows that the proposed method works well for real samples. This research demonstrates an alternative approach to detect targets of interest that holds high prospects for detecting other biomolecules or metal ions in the near future.
Co-reporter:Xuan Yang, Linfeng Gan, Chengzhou Zhu, Baohua Lou, Lei Han, Jin Wang and Erkang Wang
Chemical Communications 2014 vol. 50(Issue 2) pp:234-236
Publication Date(Web):29 Oct 2013
DOI:10.1039/C3CC47712F
We report a high-yield strategy for the synthesis of very small silver nanoclusters (2 to 5 silver atoms) formed from conventional silver salts and scaffolds as high-performance catalysts for oxygen reduction reaction (ORR). The work demonstrates that Ag NCs are excellent catalysts for ORR and show great potential in alkaline fuel cells.
Co-reporter:Xiaofang Jia, Xuan Yang, Jing Li, Dongyue Li and Erkang Wang
Chemical Communications 2014 vol. 50(Issue 2) pp:237-239
Publication Date(Web):30 Oct 2013
DOI:10.1039/C3CC47771A
Highly luminescent and stable Cu nanoclusters (NCs) have been prepared, displaying an intriguing aggregation-induced emission (AIE) feature. The attractive AIE feature allowed the CuNCs to serve as pH stimuli-responsive functional materials. Additionally, we explored the utility of CuNCs for biosensing and catalysis applications.
Co-reporter:Jinbo Zhu, Libing Zhang, Zhixue Zhou, Shaojun Dong and Erkang Wang
Chemical Communications 2014 vol. 50(Issue 25) pp:3321-3323
Publication Date(Web):04 Feb 2014
DOI:10.1039/C3CC49833F
A molecular aptamer beacon tuned DNA strand displacement reaction was introduced in this work. This strand displacement mode can be used to transform the adenosine triphosphate (ATP) input into a DNA strand output signal for the downstream gates to process. A simple logic circuit was built on the basis of this mechanism.
Co-reporter:Jiyang Liu, Xiaohui Wang, Tianshu Wang, Dan Li, Fengna Xi, Jin Wang, and Erkang Wang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 22) pp:19997
Publication Date(Web):November 10, 2014
DOI:10.1021/am505547f
Biological modification of monolithic and porous 3D graphene is of great significance for extending its application in fabricating highly sensitive biosensors. The present work reports on the first biofunctionalization of monolithic and freestanding 3D graphene foam for one-step preparation of reagentless enzymatic biosensors by controllable chitosan (CS) electrodeposition technology. Using a homogeneous three-component electrodeposition solution containing a ferrocene (Fc) grafted CS hybrid (Fc-CS), glucose oxidase (GOD), and single-walled carbon nanotubes (SWNTs), a homogeneous biocomposite film of Fc-CS/SWNTs/GOD was immobilized on the surface of 3D graphene foam by one-step electrodeposition. The Fc groups grafted on chitosan can be stably immobilized on the 3D graphene surface and keep their original electrochemical activity. The SWNTs doped into the Fc-CS matrix act as a nanowire to facilitate electron transfer and improve the conductivity of the biocomposite film. Combined with the extraordinary properties of 3D graphene foam including large active surface area, high conductivity, and fast mass transport dynamics, the 3D graphene based enzymatic biosensor achieved a large linear range (5.0 μM to 19.8 mM), a low detection limit (1.2 μM), and rapid response (reaching the 95% steady-state response within 8 s) for reagentless detection of glucose in the phosphate buffer solution.Keywords: 3D graphene; biosensor; chitosan electrodeposition; enzyme; reagentless
Co-reporter:Li Yang, Caihua Zhang, Hong Jiang, Guijuan Li, Jiahai Wang, and Erkang Wang
Analytical Chemistry 2014 Volume 86(Issue 10) pp:4657
Publication Date(Web):April 24, 2014
DOI:10.1021/ac500029z
For more than a decade, the backfilling approach for the immobilization of DNA probes has been routinely adopted for the construction of functional interfaces; however, reliably reproducing electrochemical signal amplification by this method is a challenge. In this research, we demonstrate that the insertion approach significantly bolsters the reproducibility of electrochemical signal amplification via DNA superstructures. The combination of the backfilling approach and the DNA superstructure formation poses a big challenge to reliably reproducing electrochemical signal amplification. In order to use the detection of Hg2+ as a prototype of this new strategy, a thymine-rich DNA probe that is specific to mercury ion was applied in this study. The presence of Hg2+ induces the folding of the DNA probes and inhibits the formation of DNA superstructures. By using electroactive probes ([Ru(NH3)6]3+) that are electrostatically adsorbed onto the double strands, differential pulse voltammetry (DPV) could quantitatively confirm the presence of Hg2+. A limit of detection (LOD) and a limit of quantification (LOQ) (LOQ) as low as 0.3 and 9.5 pM, respectively, were achieved. Furthermore, excellent selectivity and real sample analysis demonstrated the promising potential of this approach in future applications.
Co-reporter:Wei Hong, Youxing Fang, Jin Wang, Erkang Wang
Journal of Power Sources 2014 Volume 248() pp:553-559
Publication Date(Web):15 February 2014
DOI:10.1016/j.jpowsour.2013.09.126
•Porous Pd nanoparticles have been synthesized by a simple method.•The developed method is efficient, rapid and convenient.•Hydroquinone was used as the reductant to obtain porous Pd nanoparticles.•The as-prepared catalysts exhibit excellent electrocatalytic activity.Porous Pd nanoparticles are successfully prepared by a rapid, one-step, and efficient route with high yield in aqueous solution. The developed method is very simple, just by mixing sodium tetrachloropalladate, polyvinylpyrrolidone and hydroquinone and heated at 70 °C for 15 min. The structure and composition are analyzed by transmission electron microscope, selected-area electron diffraction, inductively coupled plasma optical emission spectrometer, X-ray diffraction, energy dispersive X-ray spectrum and X-ray photoelectron spectroscopy. Electrochemical catalytic measurement results prove that the as synthesized porous Pd nanoparticles exhibit superior catalytic activity towards ethanol and formic acid electrooxidation.
Co-reporter:Wei Hong, Jin Wang, Erkang Wang
International Journal of Hydrogen Energy 2014 Volume 39(Issue 7) pp:3226-3230
Publication Date(Web):25 February 2014
DOI:10.1016/j.ijhydene.2013.12.096
•Pd nanowires have been synthesized in the presence of bromide ions.•PVP were used as protective reagents while NaBH4 as the reductant.•The as-prepared Pd nanowires were well dispersed on carbon.•The as-prepared catalyst exhibits excellent electrocatalytic activity.•The developed method is very simple, rapid and convenient.Palladium nanowires with a diameter of about 5 nm and length of a few tens of nanometers can be synthesized in the presence of large amount of bromide ions, employing polyvinylpyrrolidone as protective reagent while sodium borohydride as reductant. The obtained Pd nanowires are well dispersed on Vulcan XC-72 carbon. The structure and composition of the as-prepared catalyst are analyzed by transmission electron microscope, X-ray diffraction, energy dispersive X-ray spectrum and inductively coupled plasma optical emission spectrometer. Electrochemical catalytic measurement results prove that the as-prepared catalyst exhibits superior electrocatalytic activity towards ethanol and formic acid electrooxidation.
Co-reporter:Jun Ai, Yuanhong Xu, Baohua Lou, Dan Li, Erkang Wang
Talanta 2014 Volume 118() pp:54-60
Publication Date(Web):15 January 2014
DOI:10.1016/j.talanta.2013.09.062
•Multifunctional fluorescent gold nanoparticles (named NAANPs) were synthesized.•NAANPs were functionalized with AS1411 and bound with N-methylmesoporphyrin IX (NMM).•NAANPs targeted to the cancer cell via the specific AS1411-nucleolin interaction.•NMM can be fluorescence-enhanced by AS1411 G-quadruplex and used as a photosensitizer.•NAANPs were used for targeted cell imaging and efficient photodynamic therapy.Herein, one multifunctional AS1411-functionalized fluorescent gold nanoparticles (named NAANPs) is synthesized and successfully applied for both targeted cancer cell imaging and efficient photodynamic therapy (PDT). The NAANPs are obtained by functionalizing the gold nanoparticles with AS1411 aptamer and then bound with one porphyrin derivative N-methylmesoporphyrin IX (NMM). Using HeLa cells over expressing nucleolin as representative cancer cells, the formed NAANPs can target to the cell surface via the specific AS1411-nucleolin interaction, which can discriminate the cancer cells from normal ones (e.g. HEK293) unambiguously. That the fluorescence intensity of NMM increased significantly upon binding to AS1411 G-quadruplex makes the NAANPs appropriate fluorescence reagent for cell imaging. Meanwhile, NMM can also be used as a photosensitizer, thus irradiation of the NAANPs by the white light from a common electric torch can lead to efficient production of cytotoxic reactive oxygen species for establishing a new type of PDT to cancer cells. Gold nanoparticles play the roles of both carrier and enhancer of the functional groups onto the cells. In addition, they not only possess inherently certain cytotoxicity to the cancer cells, but also boost the cellular uptake of the fluorescent groups. As a result, the efficiency of both the targeted cell imaging and PDT could be ensured.
Co-reporter:Yusheng Niu, Fengyue Sun, Yuanhong Xu, Zhichao Cong, Erkang Wang
Talanta 2014 Volume 127() pp:211-218
Publication Date(Web):1 September 2014
DOI:10.1016/j.talanta.2014.03.072
•Applications of electrochemical techniques in mineral analysis are summarized.•Types of electrochemical techniques and kinds of analyzed minerals are classified.•Minerals as assisting reagents for electrochemical analysis are also summarized.•Research vacancies and future development trends in these areas are discussed.This review, covering reports published in recent decade from 2004 to 2013, shows how electrochemical (EC) techniques such as voltammetry, electrochemical impedance spectroscopy, potentiometry, coulometry, etc., have made significant contributions in the analysis of minerals such as clay, sulfide, oxide, and oxysalt. It was discussed based on the classifications of both the types of the used EC techniques and kinds of the analyzed minerals. Furthermore, minerals as electrode modification materials for EC analysis have also been summarized. Accordingly, research vacancies and future development trends in these areas are discussed.
Co-reporter:Jiangtao Ren, Jiahai Wang, Jin Wang, Erkang Wang
Biosensors and Bioelectronics 2014 Volume 51() pp:336-342
Publication Date(Web):15 January 2014
DOI:10.1016/j.bios.2013.07.059
•DNA ligation was coupled to split G-quadruplex probes.•Highly selective detection of small biomolecules (ATP and NAD+) was realized.•The effect of single-base mismatch position on the ligation efficiency was also validated.•The high selectivity is attributed to cofactor/sequence-dependent activity of DNA ligase.•The non-covalent labeling strategy is simple, cost-effective and versatile.Through tuning relative thermodynamic stabilities (I, II and III), DNA ligation was coupled to split G-quadruplex probes and a versatile, non-covalent labelling and fluorescent strategy was constructed based on inhibition of template-directed G-quadruplex assembling by ligation reaction. The non-covalent complex between G-quadruplex and fluorescent probe was employed as signalling label and thus covalent modification of DNA probes with fluorescent probes was avoided. Selective detection of small biomolecules (ATP and NAD+) in the nanomolar range was realized due to the cofactor-dependent activity of DNA ligases (T4 and Escherichia coli DNA ligase). By virtue of the simple strategy, the effect of mismatch position of single-base mismatched template DNA on the ligation efficiency was validated. Meanwhile, highly mismatch-influenced ligation efficiency of ligase endows the cost-effective strategy great potential for single-nucleotide polymorphism (SNP) analysis. The non-covalent labeling strategy provides a versatile and cost-effective platform for monitor of DNA ligation, cofactor detection, SNP analysis and other ligase-based assays.
Co-reporter:Hailong Li, Wei Hong, Shaojun Dong, Yaqing Liu, and Erkang Wang
ACS Nano 2014 Volume 8(Issue 3) pp:2796
Publication Date(Web):February 24, 2014
DOI:10.1021/nn406523y
Molecular-level security devices have raised ever-increasing interest in recent years to protect data and information from illegal invasion. Prior molecular keypad locks have an output signal dependent upon not only the appropriate combination but also the exact sequence of inputs, but it cannot be reset or reprogrammed. Here, a DNA-based security system with reset and never-reported reprogram function is successfully developed in proof-of-principle, with which one can change the password in case that the system is cracked. The previous password becomes invalid in the reprogrammed security system. Interestingly, more than one password is designed to permit multiple users to access. By harnessing the intrinsic merit of the different passwords, the system can distinguish different user who is endowed with prior authority. The intelligent device is addressed on solid support and facilitates electronic processes, avoiding chemical accumulation in the system by simple removal of the electrode from the input solution and indicating a main avenue for its further development.Keywords: DNA; molecular device; molecular keypad lock; reprogram; reset
Co-reporter:Wei Hong, Jin Wang, Erkang Wang
Electrochemistry Communications 2014 40() pp: 63-66
Publication Date(Web):
DOI:10.1016/j.elecom.2013.12.026
Co-reporter:Ye Teng;Xuan Yang;Lei Han; Erkang Wang
Chemistry - A European Journal 2014 Volume 20( Issue 4) pp:1111-1115
Publication Date(Web):
DOI:10.1002/chem.201301473
Abstract
A novel approach was developed to study the relationship between DNA sequences and DNA-templated silver nanoclusters (DNA-Ag NCs) in detail by using an ordinary DNA strand as an example. Three kinds of Ag NCs are formed by using the DNA strand as a scaffold. By dividing the DNA template into several parts according to their different affinities to Ag+, it was found that the fluorescence properties of DNA-Ag NCs are related to not only the sequences but also to the position of different parts in the template, which provides a more efficient approach to obtain DNA-Ag NCs with required photoluminescence properties and may ultimately contribute to the targeted synthesis of DNA-Ag NCs.
Co-reporter:Hui Wei and Erkang Wang
Chemical Society Reviews 2013 vol. 42(Issue 14) pp:6060-6093
Publication Date(Web):05 Jun 2013
DOI:10.1039/C3CS35486E
Over the past few decades, researchers have established artificial enzymes as highly stable and low-cost alternatives to natural enzymes in a wide range of applications. A variety of materials including cyclodextrins, metal complexes, porphyrins, polymers, dendrimers and biomolecules have been extensively explored to mimic the structures and functions of naturally occurring enzymes. Recently, some nanomaterials have been found to exhibit unexpected enzyme-like activities, and great advances have been made in this area due to the tremendous progress in nano-research and the unique characteristics of nanomaterials. To highlight the progress in the field of nanomaterial-based artificial enzymes (nanozymes), this review discusses various nanomaterials that have been explored to mimic different kinds of enzymes. We cover their kinetics, mechanisms and applications in numerous fields, from biosensing and immunoassays, to stem cell growth and pollutant removal. We also summarize several approaches to tune the activities of nanozymes. Finally, we make comparisons between nanozymes and other catalytic materials (other artificial enzymes, natural enzymes, organic catalysts and nanomaterial-based catalysts) and address the current challenges and future directions (302 references).
Co-reporter:Yan Du, Bingling Li, and Erkang Wang
Accounts of Chemical Research 2013 Volume 46(Issue 2) pp:203
Publication Date(Web):December 6, 2012
DOI:10.1021/ar300011g
Nucleic acid aptamers are small sequences of DNA made via in vitro selection techniques to bind targets with high affinity and specificity. The term aptamer derives from the Latin, aptus, meaning “to fit”, emphasizing the lock-and-key relationship between aptamers and their binding targets. In 2004, aptamers began to attract researchers’ attention as new binding elements for biosensors (i.e. aptasensors). Their advantages over other sensors include a diverse range of possible target molecules, high target affinity, simple synthesis, and ability to form Watson–Crick base pairs. These attributes create an enormous array of possible sensing applications and target molecules, spanning nearly all detection methods and readout techniques. In particular, aptamers provide an opportunity for designing “label-free” sensors, meaning sensors that do not require covalently labeling a signal probe to either the analyte or the recognition element (here, the aptamer). “Label-free” systems previously could only analyze large molecules using a few readout techniques, such as when employing the other recognition elements like antibodies. “Label-free” methods are one of the most effective and promising strategies for faster, simpler, and more convenient detection, since they avoid the expensive and tedious labeling process and challenging labeling reactions, while retaining the highest degree of activity and affinity for the recognition element. “Label-free” sensors are one of the most promising future biosensors.In this Account, we describe our efforts exploring and constructing such label-free sensing strategies based on aptamers. Our methods have included using various readout techniques, employing novel nanomaterials, importing lab-on-a-chip platforms, and improving logical recognition. The resulting sensors demonstrate that aptamers are ideal tools for “label-free” sensors. We divide this Account into three main parts describing three strategies for designing “label-free” sensors: (1) Label-free, separation-free strategies. These include colorimetric sensors based on G-quadruplex-hemin complex, and fluorescent sensors based on fluorescent small molecules, novel conjugated polymers, and metal ion clusters. (2) Label-free, separation-required strategies. In this part, electrochemical sensors are introduced, including sensors with different subtechniques using an electrode array. (3) Logic sensors. Some logic recognition systems are introduced.We emphasize that label-free aptasensors are not merely simple. We hope our introduction illustrates the powerful, flexible, and smart functions of aptamers in carrying out various detection tasks or playing various recognition games. Our work is only a start. We believe this field will bring additional knowledge on general designs, anti-interference, multianalysis, minimization, and auto-operation of aptamer biosensors.
Co-reporter:Jinbo Zhu;Libing Zhang;Tao Li;Shaojun Dong
Advanced Materials 2013 Volume 25( Issue 17) pp:2440-2444
Publication Date(Web):
DOI:10.1002/adma.201205360
Co-reporter:Libing Zhang ; Jinbo Zhu ; Shaojun Guo ; Tao Li ; Jing Li
Journal of the American Chemical Society 2013 Volume 135(Issue 7) pp:2403-2406
Publication Date(Web):February 1, 2013
DOI:10.1021/ja3089857
Photoinduced electron transfer (PET) has been observed for the first time between DNA/Ag fluorescent nanoclusters (NCs) and G-quadruplex/hemin complexes, accompanied by a decrease in the fluorescence of the DNA/Ag NCs. In this PET process, a parallel G-quadruplex and the sensing sequences are blocked by a duplex. The specific combination of targets with the sensing sequence triggers the release of the G-quadruplex and allows it to fold properly and bind hemin to form a stable G-quadruplex/hemin complex. The complex proves favorable for PET because it makes the G-quadruplex bind hemin tightly, which promotes the electron transfer from the DNA/Ag NCs to the hemin FeIII center, thus resulting in a decrease in the fluorescence intensity of the DNA/Ag NCs. This novel PET system enables the specific and versatile detection of target biomolecules such as DNA and ATP with high sensitivity based on the choices of different target sequences.
Co-reporter:Libing Zhang, Jinbo Zhu, Zhixue Zhou, Shaojun Guo, Jing Li, Shaojun Dong and Erkang Wang
Chemical Science 2013 vol. 4(Issue 10) pp:4004-4010
Publication Date(Web):10 Jul 2013
DOI:10.1039/C3SC51303C
Dynamic DNA assembly, operated in an autonomous and reconfigurable manner by controlling the kinetics of strand displacement reactions (SDR), is an ideal approach to amplify the fluorescent signals for molecular diagnostic and imaging. Herein, we for the first time have demonstrated an enhancement of fluorescence intensity of DNA/Ag nanocluster-based beacons by the modulation of SDR. This is a new DNA/Ag NCs fluorescence light-up system through the use of the enhancer of G-rich overhang. Such a sensing system can be used to develop a DNA/Ag nanocluster-based beacon for the fluorescent detection of nucleic acid and thrombin with high selectivity and sensitivity, in which the detection sensitivity could be further enhanced through additional Exo III based amplification.
Co-reporter:Zhaozi Lv, Xuan Yang and Erkang Wang
Nanoscale 2013 vol. 5(Issue 2) pp:663-670
Publication Date(Web):16 Nov 2012
DOI:10.1039/C2NR33395C
Here we report that branch poly(ethylenimine) (BPEI) could be used as both a stabilizer and a reducing agent in the preparation of long-term stable polycations-functionalized graphene nanosheets (GNs) suspension with concentration as high as 5 mg mL−1. UV-vis spectroscopy, Fourier transform infrared, X-ray photo-electron spectroscopy, atomic force microscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction were used to characterize the reduction process, composition and structure of BPEI functionalized GNs (BGNs). Fourier transform infrared and X-ray photo-electron spectroscopy data revealed that the BPEI was attached to the surface of GNs through covalent bonds such as amide bond and –Ar–NH–C bond, and could prevent their aggregation through strong electrostatic repulsion. From the atomic force microscopy image and height profile of BGNs, the modality of functionalized surface of BGNs should be continuous and compact. The as-obtained BGNs could disperse well not only in water but also in other alkaline solution, salt solution and organic solvents. The as-obtained BGNs containing abundant amino groups were used as effective and controllable templates for fast and facile assembly with a series of negatively charged nanoparticles (NPs), which was probably caused by the strong electrostatic interaction between both components. This paper presents a fast, facile, controllable, efficient and green approach for preparing GNs and GNs/NPs composites of great value for applications in various fields.
Co-reporter:Youxing Fang and Erkang Wang
Nanoscale 2013 vol. 5(Issue 5) pp:1843-1848
Publication Date(Web):17 Jan 2013
DOI:10.1039/C3NR34004J
A concise synthesis of Pd nanoparticles encapsulated in a sponge-like carbonaceous support (Pd/C) was achieved by mixing a solution containing water, ethylene glycol and Pd(II) with diphosphorus pentoxide, leading to excellent catalytic performance of Pd/C towards the reduction of the model aromatic nitro compound.
Co-reporter:Chaogui Chen, Xiaowei Zhang, Jinbo Zhu, Jing Li, Libing Zhang and Erkang Wang
Nanoscale 2013 vol. 5(Issue 17) pp:8221-8226
Publication Date(Web):18 Jun 2013
DOI:10.1039/C3NR01937C
In this work, a novel ion sensing platform was constructed in a microfluidic chip based on a very easy nano-fabrication technique, with which the nanoscale channel generated along the junction of the PDMS and metal strip could serve as a salt bridge for electrochemical measurements. More importantly, we have proposed a flexible and universal ion sensing strategy based on Boolean logic, which can rapidly report the concentration of analyte by the approach method. Firstly, the performance of the nanochannel based salt bridge was characterized, and the results showed that the nanoscale salt bridge behaved comparably to the traditional ones. To illustrate the promising applications of this wonderful design, an IrOx electrode was employed to construct the on-line pH sensing device as an example, and a wide linearity range (pH 2–12) was obtained with a really high sensitivity of 74.15 mV per pH unit. Owing to the use of the logic sensing strategy, we achieved rapid identification of the sample pH on-line, and demonstrated the broad potential of our system in designing sensing devices with extremely high integration, automation and throughput.
Co-reporter:Xuan Yang, Linfeng Gan, Lei Han, Dan Li, Jin Wang and Erkang Wang
Chemical Communications 2013 vol. 49(Issue 23) pp:2302-2304
Publication Date(Web):01 Feb 2013
DOI:10.1039/C3CC00200D
A facile synthesis of chiral penicillamine protected Au nanoclusters with different optical properties has been reported. We have for the first time observed the reversal of CD signals after the scaffolds adsorbed onto the surface of Au NCs. Such Au NCs are utilized for bioimaging due to their low cytotoxicity and stable fluorescence emission.
Co-reporter:Xiaowei Zhang, Jing Li, Chaogui Chen, Baohua Lou, Lingling Zhang and Erkang Wang
Chemical Communications 2013 vol. 49(Issue 37) pp:3866-3868
Publication Date(Web):19 Mar 2013
DOI:10.1039/C3CC40905H
A self-powered 3D microfluidic electrochemiluminescence biosensing platform, integrated with a stable, environmentally-friendly and noble metal-free primary battery, was developed for the first time based on the principle of origami.
Co-reporter:Jinbo Zhu, Xuan Yang, Libing Zhang, Lingling Zhang, Baohua Lou, Shaojun Dong and Erkang Wang
Chemical Communications 2013 vol. 49(Issue 48) pp:5459-5461
Publication Date(Web):29 Apr 2013
DOI:10.1039/C3CC42028K
A novel visible multi-digit DNA keypad lock system was fabricated based on split G-quadruplex DNAzyme and silver microspheres. The final result of the keypad lock can be easily recognized by the naked eye and the number of inputs for the keypad lock can be flexibly adjusted. This molecular platform showed excellent scalability and flexibility.
Co-reporter:Youxing Fang and Erkang Wang
Chemical Communications 2013 vol. 49(Issue 83) pp:9526-9539
Publication Date(Web):14 Aug 2013
DOI:10.1039/C3CC44735A
In recent years, graphene, the two-dimensional closely packed honeycomb carbon lattice, has been attracting much attention in the field of electrochemistry due to its intrinsic properties and merits. Efforts to create novel graphene based electrochemical biosensors have led to the establishment of effective strategies for diverse bioassays, from simple molecules to complex biotargets. In this Feature Article, we provide an overview of electrochemical biosensing with graphene related materials, and discuss the role of graphene in different sensing protocols.
Co-reporter:Li Yang, Qingfeng Zhai, Guijuan Li, Hong Jiang, Lei Han, Jiahai Wang and Erkang Wang
Chemical Communications 2013 vol. 49(Issue 97) pp:11415-11417
Publication Date(Web):14 Oct 2013
DOI:10.1039/C3CC45841E
A new approach is proposed for accurate measurement of the pore sizes in a track-etched PET membrane (polyethylene terephthalate) from a nanometer scale to a submicrometer scale, which only entailed UV-Vis spectrometry.
Co-reporter:Xiaowei Zhang, Chaogui Chen, Jing Li, Libing Zhang, and Erkang Wang
Analytical Chemistry 2013 Volume 85(Issue 11) pp:5335
Publication Date(Web):May 1, 2013
DOI:10.1021/ac400805f
In this work, a novel style of a microfluidic-based bipolar system with two-direction driving electrodes and dual-channel configuration was described for the first time, which could reach 100% current efficiency in theory. More importantly, the background signal from the integrated driving electrodes was completely eliminated, when this unique design was used to construct an electrochemiluminescence (ECL) sensing platform. First, universal pH indicator was employed to study the mechanism and demonstrate that this new bipolar system possessed 100% current efficiency theoretically. Then, the Ru(bpy)32+/TPrA ECL system was introduced to construct the dual-channel bipolar ECL sensing platform, and the results of visual ECL experiments proved that the background signals from the driving electrodes were completely dispelled with our design. To illustrate the promising applications of this dual-channel device, TPrA, dopamine (DA), H2O2, and K3Fe(CN)6 were detected as model targets under different principles.
Co-reporter:Wei Hong, Yaqing Liu, Jin Wang, Erkang Wang
Electrochemistry Communications 2013 Volume 31() pp:59-62
Publication Date(Web):June 2013
DOI:10.1016/j.elecom.2013.03.006
•Carbon supported Pd nanoparticles has been synthesized through an ultrasonic way.•Commonly used ultrasonic cleaner was used for the ultrasonic synthesis.•Ethylene glycol was used to reduce chloropalladic acid.•No additional surfactants or protecting reagents were introduced.•The as-prepared catalysts exhibit superior electrocatalytic activity.Carbon supported Pd nanoparticles can be synthesized through an ultrasound assisted way. Chloropalladic acid can be reduced by ethylene glycol at room temperature with a commonly used ultrasonic cleaner. No additional surfactants or stabilizers were introduced. The Pd nanoparticles were well dispersed on Vulcan XC-72 carbon. The as-prepared catalysts exhibit superior electrocatalytic performance toward ethanol electrooxidation in alkaline solution. The developed method is simple, convenient, effective and environmentally friendly.
Co-reporter:Yuanhong Xu, Baohua Lou, Zhaozi Lv, Zhixue Zhou, Libing Zhang, Erkang Wang
Analytica Chimica Acta 2013 Volume 763() pp:20-27
Publication Date(Web):6 February 2013
DOI:10.1016/j.aca.2012.12.009
Herein, highly efficient solid-state ECL sensor was introduced for the first time onto the screen printed electrodes of the paper-based chips (PCs) based on the composite film of poly(sodium 4-styrenesulfonate) functionalized graphene (PSSG) and Nafion. Attributed to the cooperative characteristics of both PSS and graphene, PSSG ensured both effective Ru(bpy)32+ immobilization and fast electron transfer of Ru(bpy)32+ in the composite film. The ECL behaviors at the developed sensor were investigated using tripropylamine as a representative analyte and low detection limit (S N−1 = 3) of 5.0 nM was obtained. It also exhibited more excellent reproducibility (relative standard deviations of 0.63% for continuous 45 cycles) and long-term stability (∼80% of its initial ECL intensity could be retained over 3 months). More importantly, assisted by the developed ECL sensor, discrimination of 1.0 nM single-nucleotide mismatch in human urine matrix could be realized on the PCs for the first attempt. Thus, the developed sensor was confirmed with the advantages of highly sensitivity, long-term stability, simplicity, low cost, disposability, high efficiency and potential applicability.Graphical abstractHighlights► Solid-state ECL sensor was introduced into paper-based chips for the first time. ► Composite film of functionalized graphene/Nafion was used for sensor fabrication. ► Excellent reproducibility and long-term stability were obtained for the sensor. ► Single-base mismatch detection in human urine was realized on paper-based chips.
Co-reporter:Zhanhui Tao;Yinan Qin;Yaqing Liu;Lei Xu
Chinese Journal of Chemistry 2013 Volume 31( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/cjoc.201390014
Co-reporter:Zhanhui Tao;Yinan Qin;Yaqing Liu;Lei Xu
Chinese Journal of Chemistry 2013 Volume 31( Issue 6) pp:721-725
Publication Date(Web):
DOI:10.1002/cjoc.201300109
Abstract
A simple-structured 4-(2-pyridylazo)resorcinol (PAR) system presents interesting properties with dual fluorescent outputs. Modulated by solution pH two kinds of reversible switch behaviors, "ON-OFF" and "OFF-ON", were realized with the PAR system. Stimulated by different combination of external stimulus, such as metal ions, UV irradiation and solution pH, the PAR system could perform multiple logic functions including three inputs AND, two inputs INHIBIT and combinatorial "NOR/AND" in parallel. The operation of the designed system is very simple and detected with a high sensitive fluorescent signal.
Co-reporter:Xuan Yang;Linfeng Gan;Lei Han; Erkang Wang; Jin Wang
Angewandte Chemie 2013 Volume 125( Issue 7) pp:2076-2080
Publication Date(Web):
DOI:10.1002/ange.201205929
Co-reporter:Xuan Yang;Linfeng Gan;Lei Han; Erkang Wang; Jin Wang
Angewandte Chemie International Edition 2013 Volume 52( Issue 7) pp:2022-2026
Publication Date(Web):
DOI:10.1002/anie.201205929
Co-reporter:Jiangtao Ren; Jiahai Wang; Jin Wang; Erkang Wang
Chemistry - A European Journal 2013 Volume 19( Issue 2) pp:479-483
Publication Date(Web):
DOI:10.1002/chem.201202430
Co-reporter:Shanling Xu, Jiyang Liu, Tianshu Wang, Hailong Li, Yuqing Miao, Yaqing Liu, Jin Wang, Erkang Wang
Talanta 2013 Volume 104() pp:122-127
Publication Date(Web):30 January 2013
DOI:10.1016/j.talanta.2012.11.040
Developing non-invasive, sensitive and specific sensing strategies for cancerous cell detection with simple and low cost instrumentations provide great advantages in cancer research and early diagnosis of diseases. In the present work, gold nanoparticles (Au NPs) functionalized with recognition components (folic acid) and signal indicator (ferrocene) was designed to fabricate electrochemical cytosensor. The Au NPs can not only accelerate electron transfer between signal indicator and the underlying electrode but also accumulate more ferrocene on the cytosensor surface to magnify signal for improving detection sensitivity. The surface-tethered folic acid plays a key role in specific binding folate receptor-riched HeLa cells on the cytosensor surface, resulting in corresponding current signal change measured by differential pulse voltammetry method. A wide detection range from 10 to 106 cells/mL with a detection limit as low as 10 cells/mL for cancerous cells was reached in the presence of a large amount of normal ones with fast differential pulse voltammetry measurement. Detection of the captured cells can be finished within 1 min. The developed strategy provides a new way for operationally simple, rapid, sensitive and specific detection of cancerous cells.Highlights► A highly sensitive and selective cytosensor was developed. ► Surface-confined ferrocene was used as the current signal indicator. ► Gold nanoparticles play an important role in the signal magnification. ► The selective detection range of HeLa cell was from 10 to 106 cells/mL. ► Fast DPV measurement could reduce the loss of cell viability.
Co-reporter:Baohua Lou, Chaogui Chen, Zhixue Zhou, Lingling Zhang, Erkang Wang, Shaojun Dong
Talanta 2013 Volume 105() pp:40-45
Publication Date(Web):15 February 2013
DOI:10.1016/j.talanta.2012.11.062
In this paper, conducting polymer film modified electrodes were applied to fabricate paper-based chips (PCs), and different concentrations of chloride ions (Cl−) in water can be selectively detected based on the potential response towards Cl−. The three-electrode system was screen-printed on paper and the polypyrrole (PPy) film doped with Cl− was electrochemically polymerized on working electrodes through cyclic voltammetry in aqueous solution. Open circuit potential-time method was used to measure the potential response. Based on such PCs, Cl− can be selectively detected in the range of 10−7–10−2 M. Moreover, such PCs were utilized for Cl− analysis in real water samples and resulted in good results with recoveries between 113% and 124%. Besides, following the strategy we also employed this method to detect F− in water to demonstrate its general applicability. In view of its novelty, simplicity, sensitivity and low price, such PCs will potentially be utilized for the monitoring of anions in the environment, and our method made a start for the application of CMEs to PCs to design electrochemical sensors.Highlights► This novel paper-based chloride ion sensor is easy to manufacture and low-cost. ► The potential response is fast, stable, and sensitive. ► Do not need complicated and expensive instruments. ► The sensor is portable and disposable.
Co-reporter:Yuanhong Xu, Yaqing Liu, Jinbo Zhu, Erkang Wang
Talanta 2013 Volume 116() pp:308-314
Publication Date(Web):15 November 2013
DOI:10.1016/j.talanta.2013.03.089
•One impurity in synthetic DNAs was discovered to affect electrochemiluminescence.•The impurity was identified as triethylamine from process of HPLC purification.•CE–ECL was proposed to sensitively determine impurity in synthetic DNAs.•Situations which would be really affected by the TEA impurity were studied.•Ways to eliminate the impact of TEA impurity on ECL detections was discussed.The purity of the synthetic oligonucleotides is very important because it is crucial for the accuracy of the established biological assays. Herein, it was discovered that one impurity in synthetic DNAs might affect the experiment results of electrochemiluminescence (ECL) detection techniques, which was never reported before. According to a series of experiments using ECL detection methods combined with capillary electrophoresis (CE) (CE–ECL), the impurity was identified as triethylamine (TEA), which came from incomplete removal after HPLC purification of synthetic DNAs. Moreover, CE–ECL technique was for the first time to be proposed for discovering, identifying and sensitive determining the possible impurity such as TEA in various DNA samples, which was usually neglected by other detection techniques for purification quality control of synthetic oligonucleotides. A detection range from 5.00×10−10 to 2.00×10−5 M with a detection limit as low as 50 nM (S/N=3) was reached for TEA. Through further designed ECL methods and data analysis, situations which would be really affected by the impurity of TEA were studied. To avoid or eliminate the impact of the TEA impurity on ECL applications, judgment basis for choosing purification ways was discussed according to individual requirements.
Co-reporter:Zhijun Guo;Jiahai Wang
Analytical and Bioanalytical Chemistry 2013 Volume 405( Issue 12) pp:4051-4057
Publication Date(Web):2013 May
DOI:10.1007/s00216-013-6788-2
Because small molecules can be beneficial or toxic in biology and the environment, specific and sensitive detection of small molecules is one of the most important objectives of the scientific community. In this study, new signal amplification assays for detection of small molecules based on Mg2+-dependent DNAzyme were developed. A cleavable DNA substrate containing a ribonucleotide, the ends of which were labeled with black hole quencher (BHQ) and 6-carboxyfluorescein (FAM), was used for fluorescence detection. When the small molecule of interest is added to the assay solution, the Mg2+-dependent DNAzyme is activated, facilitating hybridization between the Mg2+-dependent DNAzyme and the DNA substrate. Binding of the substrate to the DNAzyme structure results in hydrolytic cleavage of the substrate in the presence of Mg2+ ions. The fluorescence signal was amplified by continuous cleavage of the enzyme substrate. Ochratoxin A (OTA) and adenosine triphosphate (ATP) were used as model analytes in these experiments. This method can detect OTA specifically with a detection limit as low as 140 pmol L−1 and detect ATP specifically with a detection limit as low as 13 nmol L−1. Moreover, this method is potentially extendable to detection of other small molecules which are able to dissociate the aptamer from the DNAzyme, leading to activation of the DNAzyme.
Co-reporter:Yuanhong Xu;Zhaozi Lv;Yong Xia;Yanchao Han
Analytical and Bioanalytical Chemistry 2013 Volume 405( Issue 11) pp:3549-3558
Publication Date(Web):2013/04/01
DOI:10.1007/s00216-012-6510-9
Graphene-nanosheet-based highly porous magnetite nanocomposites (GN-HPMNs) have been prepared using a simple solvothermal method and used as an immobilization matrix for the fabrication of a solid-state electrochemiluminescence (ECL) sensor on paper-based chips. Highly porous Fe3O4 nanocrystal clusters were coated with acrylate and wrapped tightly on the skeleton of graphene nanosheets. The structures and sizes of the GN-HPMNs could be tuned by varying the proportions of the solvents ethylene glycol and diethylene glycol. Then, the relatively highly porous ones with an average diameter of about 65 nm were combined with Nafion to form composite films on an electrode surface for immobilization of Ru(bpy)32+ (bpy is 2,2′-bipyridine). Because of their porosity, negatively charged surface, and cooperative characteristics of magnetic nanomaterials and graphene, under an external magnetic field, the GN-HPMNs ensured effective immobilization, excellent electron transfer, and long-term stability of Ru(bpy)32+ in the composite film. The sensor developed exhibited excellent reproducibility with a relative standard deviation of 0.65 % for 30 continuous cycles. It was found to be much more favorable for detecting compounds containing tertiary amino groups and DNAs with guanine and adenine. A detection limit (signal-to-noise ratio of 3) of 5.0 nM was obtained for tripropylamine. As an application example, 0.5 nM single-nucleotide mismatch could be detected. This was the first attempt to introduce magnetic nanomaterials and an external magnetic field into paper-based chips. The sensor developed has the advantages of high sensitivity, good stability, and wide potential applicability as well as simplicity, low cost, and good disposability.
Co-reporter:Libing Zhang, Jinbo Zhu, Jun Ai, Zhixue Zhou, Xiaofang Jia, Erkang Wang
Biosensors and Bioelectronics 2013 Volume 39(Issue 1) pp:268-273
Publication Date(Web):15 January 2013
DOI:10.1016/j.bios.2012.07.058
An effective G-quadruplex-based probe has been constructed for rapid and sensitive detection of Cu2+. In this probe, an anionic porphyrin, protoporphyrin IX (PPIX) served as a reference signal, which binds to G-quadruplex specifically and the fluorescence intensity increases sharply. While, in the presence of Cu2+, the G-quadruplex can catalyze the related Cu2+ insertion into the protoporphyrin, the fluorescent intensity is decreased. The fluorescence of the response ligand could be selectively quenched in the presence of Cu2+ and not interfered by other metal ions. The probe provided an effective platform for reliable detection of Cu2+ with a detection limit as low as 3.0 nM, the high sensitivity was attributed to the strong metalation of PPIX with Cu2+ catalyzed by G-quadruplex (PS5.M). Linear correlations were obtained over the logarithm of copper ion concentration in the range from 8×10−9 M to 2×10−6 M (R=0.998). The G-quadruplex-based probe also could be used to detect Cu2+ in real water samples. Additionally, these striking properties endow the G-quadruplex-ligand with a great promise for analytical applications.Highlights► A novel sensitive G-quadruplex-based probe for Cu2+ was developed. ► The probe was based on Cu2+-induced fluorescence quenching. ► This probe is simple and cost-efficient in designing and operation. ► The detection limit can be down to 3.0 nM. ► The probe could be used to detect Cu2+ in real water samples.
Co-reporter:Jiyang Liu, Yinan Qin, Dan Li, Tianshu Wang, Yaqing Liu, Jin Wang, Erkang Wang
Biosensors and Bioelectronics 2013 Volume 41() pp:436-441
Publication Date(Web):15 March 2013
DOI:10.1016/j.bios.2012.09.002
Electrochemical methods have attracted considerable attention for developing cytosensing system since they can decrease the cost and time requirement for cell detection with simple instrumentation. Herein, a label-free electrochemical cytosensor with surface-confined ferrocene as signal indicator was developed for highly sensitive and selective detection of cancer cell. With layer-by-layer (LBL) self-assembly technique, positively charged poly(ethylene imine) functionalized with ferrocene (Fc-PEI) and negatively charged single-wall carbon nanotubes (SWNTs) were alternately assembled on 3-mercaptopropionic acid (MPA) modified gold substrate. Folic acid (FA) was covalently bonded onto SWNTs surface to specifically recognize cancer cells according to the high affinity of FA for folate receptor (FR) on cellular surface. The developed cytosensor presented high sensitivity and selectivity for the detection of human cervical carcinoma (HeLa) cell. By using fast-response differential pulse voltammetry (DPV) method, a wide detection range from 10 to 106 cells/mL with a detection limit as low as 10 cells/mL was reached even in the presence of a large amount of non-cancerous cells.Highlights► A cytosensor with high sensitivity and selectivity was developed. ► Folic acid was used to specifically recognize cancer cells. ► Surface-confined ferrocene was used as the signal indicator. ► The detection concentration range of HeLa cell was from 10 to 106 cells/mL. ► Fast DPV measurement could reduce the loss of cell viability.
Co-reporter:Hailong Li, Jiyang Liu, Youxing Fang, Yinan Qin, Shanling Xu, Yaqing Liu, Erkang Wang
Biosensors and Bioelectronics 2013 Volume 41() pp:563-568
Publication Date(Web):15 March 2013
DOI:10.1016/j.bios.2012.09.024
Histidine and cysteine detection is critically important since an abnormal level of histidine or cysteine is an indicator for many diseases. In this paper, we demonstrated a novel label-free, G-quadruplex-based approach for simultaneous detection of histidine and cysteine. The present assay is based on the highly specific interaction among amino acids (histidine or cysteine), Cu2+ and NMM/G-4 (NMM: N-methylmesoporphyrin IX; G-4: G-quadruplex). The fluorescence intensity of NMM was dramatically enhanced in the presence of G-quadruplex formed from 24GT, which can be effectively quenched by cupric ion (Cu2+) due to the chelation of Cu2+ by NMM as well as the unfolding of G-quadruplex by Cu2+. The presence of histidine or cysteine will disturb the interaction between Cu2+ and NMM/G-4 because of the strong binding affinity of Cu2+ to the imidazole group of histidine or the interaction of Cu2+ with thiol group in cysteine, leading to distinct fluorescence emission intensity. High selectivity is conferred by the use of cysteine-masking agent N-ethylmaleimide (NEM), which helps to discriminate histidine from cysteine. At last, a novel and simple approach was developed to determine each precise concentration of histidine and cysteine according to the different response of the system with and without NEM. Importantly, histidine can be also detected even in the presence of a large amount of other amino acids. A detection limit as low as 3 nM for histidine and 5 nM for cysteine was obtained by practical measurement rather than conventional calculation (S/N=3), confirming the high sensitivity of the present approach. Meanwhile, this sensing protocol can determine histidine and cysteine in diluted biological samples such as urine, exhibiting great potential to meet the need of practical application.Highlights► A label-free, G-quadruplex-based approach for histidine and cysteine detection was provided. ► The present fluorescent method is endowed with high sensitivity and selectivity. ► Detection limits 3 nM for histidine and 5 nM for cysteine were achieved by practical measurement. ► Histidine and cysteine can be detected in spite of the interference from urine.
Co-reporter:Jiyang Liu, Shaojun Guo, Lei Han, Tianshu Wang, Wei Hong, Yaqing Liu and Erkang Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 38) pp:20634-20640
Publication Date(Web):16 Aug 2012
DOI:10.1039/C2JM34494G
In this contribution, lipid monolayer membrane functionalized graphene sheets were prepared using a facile method. Interactions between the graphene and different types of liposomes, including charged and neutral, were also investigated. We found that the anionic liposomes could spontaneously self-organize into lipid monolayer membranes, partially covering the surface of graphene sheets. The resultant lipid monolayer functionalized graphene nanomaterials exhibited high stability in aqueous solution and an excellent performance as carrier for loading the anticancer drug, doxorubicin (DOX), with a high loading capacity of 70%. The loaded drug can be released under pH control. 10% and 14% of the bound DOX was released after 54 h at pH 10.0 and 7.0, respectively. Whereas, about 70% of DOX was released after 54 h at pH 5.0.
Co-reporter:Xiaofang Jia, Jing Li and Erkang Wang
Nanoscale 2012 vol. 4(Issue 18) pp:5572-5575
Publication Date(Web):26 Jun 2012
DOI:10.1039/C2NR31319G
One-pot fabrication of fluorescent carbon dots was facilely developed by directly heating ascorbic acid aqueous solution at 90 °C. The resulting carbon dots possess excitation, pH and polarity-dependent luminescence and upconversion fluorescence properties.
Co-reporter:Wen Ren, Chengzhou Zhu and Erkang Wang
Nanoscale 2012 vol. 4(Issue 19) pp:5902-5909
Publication Date(Web):30 Jul 2012
DOI:10.1039/C2NR31410J
Mercury which is a very important pollutant has drawn significant attention in recent research. So far, among the various detection methods, the strategies based on surface-enhanced Raman scattering (SERS) are quite attractive because of the high sensitivity, and especially as it is reported that Hg2+ can be directly detected by SERS without tagging. However, the procedure for the direct SERS detection of mercury is still unclear with little experimental evidence, limiting further development of Hg2+ detection by SERS. Herein, we performed a simple method based on SERS for the detection of mercury ions in water without tagging. It is established that in only 2 min, low concentration of Hg2+ can be recognized based on the decrease of SERS intensity. The detection procedure is investigated by multiple characterizations and the mechanism proven by the obtained data provides a practical way to further improve the sensitivity of the SERS detection. It is demonstrated that the interaction between Hg2+ and Ag nanoparticles (Ag NPs) could occur in a short time, which includes the complexation of Hg2+ with citrate and the formation of amalgam due to the reduction of Hg2+. This interaction influences the surface plasmon resonance (SPR) property of Ag NPs and thereby decays the electromagnetic enhancement of Ag NPs; meanwhile the interaction also causes the zeta potential decrease of Ag NPs and accordingly affects the adsorption of Raman reporter molecules on the surface of Ag NPs. Therefore, the weakness of SERS intensity in the presence of Hg2+ should be mainly attributed to the interaction between Hg2+ and Ag NPs. From the mechanism demonstrated, it can be speculated that using fewer Ag NPs in the detection could improve the sensitivity, because at low Hg2+ concentration the interaction becomes stronger since every Ag nanoparticle acts with more Hg2+ ions. Accordingly, we establish that 90.9 pM (18.2 ppt) Hg2+ is detected in 18 μM Ag NPs, which is much lower than that in reported papers.
Co-reporter:Yan Du, Shaojun Guo, Haixia Qin, Shaojun Dong and Erkang Wang
Chemical Communications 2012 vol. 48(Issue 6) pp:799-801
Publication Date(Web):03 Nov 2011
DOI:10.1039/C1CC15303J
A new electrochemical label-free biosensor based on target-induced conjunction of a split aptamer as new chiral selector for oligopeptide using graphene–mesoporous silica–gold NP hybrids (GSGHs) as magnified sensing platform is firstly reported, which showed high sensitivity and selectivity for the detection of D-vasopressin (D-VP).
Co-reporter:Yaqing Liu, Jiangtao Ren, Yinan Qin, Jing Li, Jiyang Liu and Erkang Wang
Chemical Communications 2012 vol. 48(Issue 6) pp:802-804
Publication Date(Web):05 Dec 2011
DOI:10.1039/C1CC15979H
An aptamer-based security system mimicking keypad lock function was successfully designed. The system was turned “ON” with a strong fluorescent output signal only when the inputs were added according to the correct combination and exact sequence. Otherwise, the system was kept “OFF” to prevent illegal access.
Co-reporter:Hailong Li, Dan Li, Jiyang Liu, Yinan Qin, Jiangtao Ren, Shanling Xu, Yaqing Liu, Dirk Mayer and Erkang Wang
Chemical Communications 2012 vol. 48(Issue 20) pp:2594-2596
Publication Date(Web):10 Jan 2012
DOI:10.1039/C2CC17591F
Signal amplification originating from electrochemical current rectifier (ECR) was firstly applied to construct a cytosensor for rapid and non-invasive detection of folate receptor-rich cancer cells with high sensitivity. It exhibits a broad linear range with a detection limit as low as 10 cells mL−1 even in the presence of a large number of normal cells.
Co-reporter:Weiwei Guo, Jipei Yuan and Erkang Wang
Chemical Communications 2012 vol. 48(Issue 25) pp:3076-3078
Publication Date(Web):01 Feb 2012
DOI:10.1039/C2CC17155D
A unique heterophase ligand exchange induced etching process was used to transform gold nanoparticles into organic-soluble fluorescent gold clusters which were assigned to Au8 by optical spectroscopy and MALDI-TOF mass spectrometry. Both the annihilation electrochemiluminescence of fluorescent Au8 clusters in organic solution and the coreactant electrochemiluminescence of Au8 cluster film in aqueous solution were studied.
Co-reporter:Jinbo Zhu, Libing Zhang and Erkang Wang
Chemical Communications 2012 vol. 48(Issue 98) pp:11990-11992
Publication Date(Web):29 Oct 2012
DOI:10.1039/C2CC36693B
A special DNA calliper made of a split G-quadruplex was constructed to measure the length of DNA in a single-digit base number range between two selected sequences. The enhanced fluorescence of PPIX changed with the distance between two G-rich segments.
Co-reporter:Libing Zhang, Shaojun Guo, Shaojun Dong, and Erkang Wang
Analytical Chemistry 2012 Volume 84(Issue 8) pp:3568
Publication Date(Web):March 14, 2012
DOI:10.1021/ac2032194
The designed synthesis of new nanomaterials with controlled shape, composition, and structure is critical for tuning their physical and chemical properties, and further developing interesting analytical sensing devices. Herein, we presented that Pd nanowires (NWs) can be used as a new biosensing platform for high-sensitivity nucleic acid detection. The general sensing concept is based on the fact that Pd NWs can adsorb the fluorescently labeled single-stranded DNA probe and lead to substantial fluorescence quenching of dye, followed by specific hybridization with the complementary region of the target DNA sequence. This results in desorption of double-stranded DNA from Pd NWs surface and subsequent recovery of fluorescence. Furthermore, an amplification strategy based on Pd NWs for nucleic acid detection by using exonuclease III (Exo III) was demonstrated. The present dual-magnification sensing system combined Pd NWs with Exo III has a detection range of 1.0 nM to 2.0 μM with the detection limit of 0.3 nM (S/N = 3), which is about 20-fold higher than that of traditional unamplified homogeneous assays.
Co-reporter:Chunhe Li, Erkang Wang, and Jin Wang
ACS Synthetic Biology 2012 Volume 1(Issue 6) pp:229
Publication Date(Web):May 4, 2012
DOI:10.1021/sb300020f
Metabolic networks have gained broad attention in recent years as a result of their important roles in biological systems. However, how to quantify the global stability of the metabolic networks is still challenging. We develop a probabilistic landscape approach to investigate the global natures of the metabolic system under external fluctuations. As an example, we choose a model of the carbohydrate metabolism and the anaplerotic synthesis of oxalacetate in Aspergillus niger under conditions of citric acid accumulation to explore landscape topography. The landscape has a funnel shape, which guarantees the robustness of system under fluctuations and perturbations. Robustness ratio (RR), defined as the ratio of gap between lowest potential and average potential versus roughness measured by the dispersion or square root of variations of potentials, can be used to quantitatively evaluate the global stability of metabolic networks, and the larger the RR value, the more stable the system. Results of the entropy production rate imply that nature might evolve such that the network is robust against perturbations from environment or network wirings and performs specific biological functions with less dissipation cost. We also carried out a sensitivity analysis of parameters and uncovered some key network structure factors such as kinetic rates or wirings connecting the protein species nodes, which influence the global natures of the system. We found there is a strong correlation between the landscape topography and the input-output response. The more stable and robust the metabolic network is, the sharper the response is.Keywords: fluctuations; global stability; metabolic network; probabilistic landscape; robustness ratio;
Co-reporter:Dongyue Li, Jing Li, Xiaofang Jia, Yanchao Han, Erkang Wang
Analytica Chimica Acta 2012 Volume 733() pp:23-27
Publication Date(Web):6 July 2012
DOI:10.1016/j.aca.2012.04.030
A simple, rapid and sensitive sensing platform for the detection of As(III) has been fabricated in neutral media based on the mercaptoethylamine modified Au electrode. A wide detection range of 0.2–300 μg L−1 and a low detection limit of 0.02 μg L−1 were obtained with a preconcentration time of 100 s under optimal conditions. Compared with previous studies, this work shows obvious advantages that it not only suppresses the Cu(II) interference, but also can detect the As(III) in natural water samples at the original pH avoiding high concentration acidic media. Moreover, the practical application of the proposed method was verified in the lake water sample determination.Graphical abstractIn this work, the mercaptoethylamine modified Au electrode (MEA/Au electrode) was investigated for arsenic detection by differential pulse anodic stripping voltammetry (DPASV). This method offers obvious advantages that it not only suppresses the Cu(II) interference, but also can detect the As(III) in natural water samples at the original pH with high stability and good reproducibility.Highlights► A simple, sensitive sensing platform for As(III) has been fabricated in neutral media. ► The as-prepared sensor suppresses the Cu(II) interference. ► This method monitors As(III) at the original pH of natural water samples. ► This method was successfully applied for the determination of As(III) in real samples. ► The as-prepared sensor has high stability and good reproducibility.
Co-reporter:Chaogui Chen, Yan Du, Jing Li, Xiurong Yang, Erkang Wang
Analytica Chimica Acta 2012 Volume 738() pp:45-50
Publication Date(Web):13 August 2012
DOI:10.1016/j.aca.2012.06.019
In this work, we explored a novel fabrication method to construct Au and Ag electrodes on chip, utilizing the different solubility of gold and silver in different etching solutions. KI-I2 etching solution and 50% HNO3 were chosen to dissolve the metal layers alternatively. Planar electrodes with gold and silver could be simultaneously and accurately patterned on chip using photolithographic technique. The as-prepared electrode could be directly served as integrated three-electrode system for electrochemical measurement. Based on it, a sensing strategy has been carried out using home-made electrochemical sensing (ECS) chip, which depended on the competition of double strand DNA and Hg(II)-mediated T–T base pairs (T-Hg(II)-T). Actually, a mercury specific oligonucleotide (MSO) was immobilized onto the thus-fabricated gold working electrode and employed as the sensing element. Chronocoulometry (CC) was chosen to monitor the differences of surface charge volume and quantify the concentrations of Hg(II) ions with a low detection limit down to 1 nM. Therefore, a facile method to fabricate Au and Ag electrodes has been demonstrated to simplify the production of ECS chip. The ECS chip was finally used for constructing an effective sensing platform for sensitive Hg(II) determination, which held promising potential for designing ECS chip in lab-on-a-chip device or point-of-care diagnosis.Graphical abstractIn this work, we explored a novel method to fabricate multi-metallic planar electrodes and constructed electrochemical sensing (ECS) chip for Hg(II) determination. Chronocoulometry was carried out to measure the differences of surface charge volume owing to specific activity of T-Hg(II)-T formation competed with double strand DNA. The facile fabrication of multi-planar electrodes and sensing platform endowed the ECS chip with great promise in environmental monitoring.Highlights► A novel fabrication method was explored to prepare multi-metallic planar electrodes. ► Electrochemical sensing (ECS) chip has been constructed for Hg(II) analysis. ► Sensing strategy based on T-Hg(II)-T formation competed with dsDNA has been built. ► Chronocoulometry (CC) was carried out to measure the differences of surface charge. ► It resulted in a high sensitive, high selective Hg(II) determination in practical samples.
Co-reporter:Dongyue Li, Jing Li, Xiaofang Jia, Yanchao Han, Erkang Wang
Analytica Chimica Acta 2012 Volume 741() pp:114
Publication Date(Web):5 September 2012
DOI:10.1016/j.aca.2012.07.001
Co-reporter:Jun Ai, Tao Li, Bingling Li, Yuanhong Xu, Dan Li, Zuojia Liu, Erkang Wang
Analytica Chimica Acta 2012 Volume 741() pp:93-99
Publication Date(Web):5 September 2012
DOI:10.1016/j.aca.2012.06.048
In this article, we reported a novel approach for in situ labeling and imaging HeLa cancer cells utilizing a bifunctional aptamer (AS1411) and its fluorescent ligand, protoporphyrin IX (PPIX). In the presence of potassium ion, AS1411 folded to G-quadruplex structure, binded fluorescent ligand (PPIX) with fluorescent enhancement, and targeted the nucleolin overexpressed by cancer cells. Consequently, bioimaging of cancer cells specifically were realized by laser scanning confocal microscope. The bioimaging strategy with AS1411–PPIX complex was capable to distinguish HeLa cancer cells from normal cells unambiguously, and fluorescence imaging of cancer cells was also realized in human serum. Moreover, the bioimaging method was very facile, effective and need not any covalent modification. These results illustrated that the useful approach can provide a novel clue for bioimaging based on non-covalent bifunctional aptamer in clinic diagnosis.Graphical abstractIn this work, we report a novel approach to in situ labeling and imaging of a cellular protein nucleolin utilizing a multifunctional anticancer aptamer combined with its fluorescent ligand.Highlights► AS1411 bind protoporphyrin IX and enhances the fluorescence signal remarkably. ► According to LSCM experiment, HeLa cells were imagined by AS1411–PPIX. ► Aptamer-based bioimaging plays an important role for need not any covalent modification.
Co-reporter:Yinan Qin, Jiyang Liu, Dan Li, Lei Xu, Yaqing Liu, Erkang Wang
Electrochemistry Communications 2012 Volume 18() pp:81-84
Publication Date(Web):2012
DOI:10.1016/j.elecom.2012.02.024
The possibility of using electrochemical methods to investigate cell immobilization and natural physiological states provides great advances in life science research and public health protection. Herein, cytosensors with surface-confined ferrocene as signal indicator were developed to study the immobilization of human cervical carcinoma (HeLa) cells. With layer-by-layer (LBL) technique positively charged ferrocene functionalized poly(allylamine hydrochloride) (Fc-PAH) and negatively charged single-wall carbon nanotubes (SWNTs) were alternately assembled on 3-mercaptopropionic acid (MPA) modified gold substrates. The as-prepared cytosensors presented good biocompatibility and HeLa cells could keep viability for 72 h on the materials according to the proliferation results. With differential pulse voltammetry (DPV) measurements the cytosensors exhibited high sensitivity to the detection of HeLa cells within a wide concentration range from 10 to 107 cells/mL.Highlights► A cell-based biosensor with high sensitive was prepared. ► Surface-confined ferrocene was used as signal indicator. ► The biosensor can avoid the effect of external redox probe on the cells. ► Long time of electric field effect on the cells was avoided with DPV measurement. ► The detection concentration range of HeLa cell was from 10 to 107 cells/mL.
Co-reporter:Yuanhong Xu, Erkang Wang
Electrochimica Acta 2012 Volume 84() pp:62-73
Publication Date(Web):1 December 2012
DOI:10.1016/j.electacta.2012.03.147
This review shows how magnetic micro/nano particles have made significant contributions in the developments of electrochemical and Ru(bpy)32+ electrochemiluminescent biosensors, including immuno-, enzyme, DNA, aptamer ones. Reports published from 2007 to November 2011 have been covered herein. More importantly, different aspects of the biosensors such as modes of magnetic particles, detection and flow injection techniques, analytes and the corresponding sensitivity and sample matrix, as well as several noticeably prominent characteristics have been summarized and discussed in detail. Accordingly, research opportunities and future development trends in these areas are discussed.Highlights► Magnetic particles used in electrochemical biosensors were reviewed. ► Different aspects of the biosensors and prominent characteristics were summarized. ► Reports published from 2007 to November 2011 have been covered. ► Research opportunities and perspectives in these fields were discussed.
Co-reporter:Haixia Qin, Jiyang Liu, Chaogui Chen, JiaHai Wang, Erkang Wang
Analytica Chimica Acta 2012 Volume 712() pp:127-131
Publication Date(Web):27 January 2012
DOI:10.1016/j.aca.2011.10.044
Here we demonstrate for the first time that by physically adsorbing aptamer onto conductive film assembled via alternate adsorption of graphene/polyelectrolyte and methylene blue/polyelectrolyte, a label-free electrochemical aptasensor with high sensitivity and selectivity for peptide detection is constructed. Graphene multilayer derived from layer-by-layer assembly has played significant roles in this sensing strategy: allowing accumulation of methylene blue, facilitating electron transfer and providing much more adsorption site. As compared to previous electrochemical aptasensors, the current sensor based on graphene multilayer alternated with electroactive molecule layer offers extremely high capability for sensitive detection of target without interference of environmental surrounding. This electroactive probe-confined graphene multilayer confers great flexibility to combine with differential pulse voltammetry (DPV) together. In the presence of target d entiomer of arginine vasopressin (d-VP), the binding of peptide to aptamer block the electron transfer process of MB, leading to decreased current peak of DPV. By this way, this electrochemical aptasensor based on electroactive molecule-intercalated graphene multilayer provide highly sensitive and specific detection of d-VP with the lowest detectable concentration of 1 ng mL−1 and a wide detection range from 1 to 265 ng mL−1.Graphical abstractHighlights► An electrochemical aptasensor for selective detection of peptide is constructed. ► This aptasensor is based on grapheme multilayer via layer-by-layer assembly. ► Such multilayer facilitates electron transfer and provides more adsorption sites.
Co-reporter:Jing Li, Shaojun Guo and Erkang Wang
RSC Advances 2012 vol. 2(Issue 9) pp:3579-3586
Publication Date(Web):06 Feb 2012
DOI:10.1039/C2RA01070D
Electrochemiluminescence (ECL) has received considerable interest for broad applications due to the potential remarkably high sensitivity and extremely wide dynamic range. In recent years, due to the unique physical (structural, electronic, magnetic and optical) and chemical (catalytic) properties of nanomaterials (NMs), great efforts have been made to investigate their application in ECL. In this review, we present a general description of ECL related to NMs as the emitter. It mainly focuses on the basic mechanisms and the development of an ECL sensing platform fabricated from semiconductor nanocrystals and metal nanoclusters. Finally, we conclude with a look at the future challenges and prospects of the development of ECL.
Co-reporter:Jing Li
The Chemical Record 2012 Volume 12( Issue 1) pp:177-187
Publication Date(Web):
DOI:10.1002/tcr.201100017
Abstract
Electrochemiluminescence (ECL) of tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)32+] has received considerable interest over broad applications due to its remarkably high sensitivity and extremely wide dynamic range. After a brief introduction of the ECL of Ru(bpy)32+, an overview of our recent research on enhanced ECL, fabrication of solid-state ECL sensors, analytical application of an effective bioassay, and alignment of ECL with capillary electrophoresis (CE) and microchip CE is discussed in detail. Finally, we conclude with a look at the future challenges and prospects of the development of ECL. DOI 10.1002/tcr.201100017
Co-reporter:Wei Hong;Dr. Yan Du;Tianshu Wang;Jiyang Liu;Dr. Yaqing Liu; Jin Wang; Erkang Wang
Chemistry - A European Journal 2012 Volume 18( Issue 47) pp:14939-14942
Publication Date(Web):
DOI:10.1002/chem.201203286
Co-reporter:Xiaofang Jia;Jing Li; Erkang Wang
Chemistry - A European Journal 2012 Volume 18( Issue 42) pp:13494-13500
Publication Date(Web):
DOI:10.1002/chem.201103768
Abstract
This work describes a novel strategy for the highly sensitive and selective detection of cysteine (Cys) and glutathione (GSH) based on the Hg2+–AGRO100–malachite green (MG) complex system. The dye MG, which has a very low quantum yield in aqueous solution by itself, can bind with the thymine-rich DNA AGRO100 in the presence of Hg2+ ions to generate a striking fluorescence intensity enhancement of 1000-fold. As sulfur-containing amino acids, Cys and GSH effectively sequester Hg2+ ions from the Hg2+–AGRO100–MG complex structure to switch the ‘lit-up’ chemosensor to the ‘off’ state (about a 50-fold fluorescence intensity decrease), thus providing a facile, but effective, method to probe for Cys/GSH. The fluorescence titration, UV absorption, CD, and Raman spectra provide some insight into the structural and chemical basis for the enhancement effect. The formation of the Hg2+–AGRO100–MG complex significantly affects the electronic structure and conformation of the MG molecule by leading to an extended π system, which is the likely origin of the observed striking fluorescence intensity enhancement. Notably, the proposed sensing platform exhibits exquisite selectivity and sensitivity toward Cys/GSH with limits of detection of 5 nM for Cys and 10 nM for GSH, respectively. Furthermore, the straightforward assay design avoids labeling of the probe, uses only commercially available materials, and still displays comparable sensitivity and excellent selectivity.
Co-reporter:Xiaofang Jia, Jing Li, Lei Han, Jiangtao Ren, Xuan Yang, and Erkang Wang
ACS Nano 2012 Volume 6(Issue 4) pp:3311
Publication Date(Web):March 14, 2012
DOI:10.1021/nn3002455
Metal nanoclusters have received considerable interest due to their unique properties and potential applications in numerous fields. Particularly, newly emerging Cu nanoclusters offer excellent potential as functional biological probes. In this work, we for the first time report that the fluorescence of DNA-hosted Cu nanoclusters is very sensitive to base type located in the major groove. This intriguing finding provides a sensitive fluorimetric diagnostic of the mismatch type in a specific DNA sequence, which is difficult to achieve by traditional methods. Furthermore, the research results have shed some light on the luminescent mechanism of Cu nanoclusters. Owing to its high specificity and easy operation without rigorously controlled temperature and arduous probe DNA design, it is expected that the proposed procedure can provide a tool for early diagnosis and risk assessment of malignancy.Keywords: Cu nanoclusters; DNA duplexes; DNA mismatches; DNA recognition; fluorescence
Co-reporter:Li Wang, Jinbo Zhu, Lei Han, Lihua Jin, Chengzhou Zhu, Erkang Wang, and Shaojun Dong
ACS Nano 2012 Volume 6(Issue 8) pp:6659
Publication Date(Web):July 23, 2012
DOI:10.1021/nn300997f
In this work, a GO/aptamer system was constructed to create multiplex logic operations and enable sensing of multiplex targets. 6-Carboxyfluorescein (FAM)-labeled adenosine triphosphate binding aptamer (ABA) and FAM-labeled thrombin binding aptamer (TBA) were first adsorbed onto graphene oxide (GO) to form a GO/aptamer complex, leading to the quenching of the fluorescence of FAM. We demonstrated that the unique GO/aptamer interaction and the specific aptamer–target recognition in the target/GO/aptamer system were programmable and could be utilized to regulate the fluorescence of FAM via OR and INHIBIT logic gates. The fluorescence changed according to different input combinations, and the integration of OR and INHIBIT logic gates provided an interesting approach for logic sensing applications where multiple target molecules were present. High-throughput fluorescence imagings that enabled the simultaneous processing of many samples by using the combinatorial logic gates were realized. The developed logic gates may find applications in further development of DNA circuits and advanced sensors for the identification of multiple targets in complex chemical environments.Keywords: aptamer; ATP; graphene; logic gates; multiplex detection; thrombin
Co-reporter:Youxing Fang, Shaojun Guo, Dan Li, Chengzhou Zhu, Wen Ren, Shaojun Dong, and Erkang Wang
ACS Nano 2012 Volume 6(Issue 1) pp:400
Publication Date(Web):December 21, 2011
DOI:10.1021/nn2046373
We propose an ingenious method for synthesizing cross-linked hollow fluorescent carbon nanoparticles (HFCNs) with green emission by simply mixing acetic acid, water, and diphosphorus pentoxide. This is an automatic method without external heat treatment to rapidly produce large quantities of HFCNs, in contrast to other syntheses of fluorescent carbon nanoparticles that required high temperature, complicated operations, or long reaction times. Characterizations of HFCNs through high-resolution transmission electron microscopy, infrared/Raman spectroscopy, and X-ray diffraction indicate that abundant small oxygenous graphite domains existed and endowed the HFCNs with fluorescent properties. After simple post-treatments, the cross-linked HFCNs can be used for cell-imaging applications. Compared with traditional dyes and CdTe quantum dots, HFCNs are the superior fluorescent bioimaging agent according to their low toxicity, stability, and resistance to photobleaching. The HFCNs were also applied to watermark ink and fluorescent powder, showing their promising potentials for further wide usage.Keywords: fluorescent bioimaging; fluorescent carbon nanoparticle; hollow nanoparticles; one-step synthesis
Co-reporter:Zhijun Guo, Jiahai Wang, Erkang Wang
Talanta 2012 Volume 89() pp:253-257
Publication Date(Web):30 January 2012
DOI:10.1016/j.talanta.2011.12.022
In this study, based on ion-current rectification in the conically shaped nanochannel embedded in polyethylene terephthalate (PET) membrane, we have selectively discriminated three small biomolecules. Because three positive biomolecules (Hoechst 33342, Propidium and Bupivacaine) have different hydrophobicities, their interactions with inside wall of the conical nanochannel are different and their binding affinities can be derived from Langmuir absorption model. Therefore, we can successfully discriminate these small biomolecules. The highest binding constant was obtained for the small molecule with highest hydrophobicity. Another interesting result is that the detection limit for the small molecule with the highest binding constant shifts to submicromole.Highlights► Hydrophobic biomolecules can be selectively detected via nanopore. ► The detection limit for each one is dependent on its affinity toward the membrane. ► The molecule with the highest binding affinity has the lowest detection limit.
Co-reporter:Jiyang Liu, Shaojun Guo, Lei Han, Wen Ren, Yaqing Liu, Erkang Wang
Talanta 2012 Volume 101() pp:151-156
Publication Date(Web):15 November 2012
DOI:10.1016/j.talanta.2012.09.013
Multiple pH-sensitive composites have been prepared through non-covalently functionalizing chemically converted graphene (CCG) with chitosan. Chtiosan exhibits as polybases and CCG shows characteristics of polyacids. Owing to the synergistic effects of chitosan and CCG, chitosan decorated graphene (CS-G) presents a multiple pH-responsive behavior that it can be dispersed well whether in acidic or in basic solution but aggregated in near-neutral solution. After CS-G was modified through a controlled deposition and cross-linking process of chitosan, the resultant cross-linked chitosan decorated graphene (CLCS-G) can be converted to a different pH-sensitive material that disperses only in acidic solution. Both CS-G and CLCS-G present a reversible switching between dispersed and aggregated states with pH as a stimulus. The unique pH response mechanisms of CS-G and CLCS-G have been further investigated by zeta potential analysis. Based on the unique pH-responsive property of CS-G, a stable and repeatable pH-driven switch was developed for monitoring pH change.Highlights► Multiple pH-responsive chitosan/graphene composites were prepared. ► The pH-response could be controlled by changing the state of chitosan. ► Free chitosan/graphene dispersed either in acid or in basic solutions. ► Cross-linked chitosan/graphene only dispersed in acid solution. ► A repeatable pH-driven switch was developed.
Co-reporter:Jun Ai, Weiwei Guo, Bingling Li, Tao Li, Dan Li, Erkang Wang
Talanta 2012 Volume 88() pp:450-455
Publication Date(Web):15 January 2012
DOI:10.1016/j.talanta.2011.10.057
Herein, a novel kind of silver nanocluster is synthesized simply by mixing G-quadruplex template with silver ions and reduction reagent (NaBH4, here). AS1411 (a G-quadruplex that can bind nucleolin overexpressed in cancer cells) is used as the main model template to prove the synthesis protocol and its potential application. We used fluorescence assay, CD, MALDI TOF MS, and TEM to characterize the silver nanocluster. It is found that after formation of the silver nanocluster, AS1411 still keeps its structure and is able to bind with nucleolin in cancer cell. Meanwhile, this binding behavior can greatly enhance the fluorescence intensity of the silver nanocluster. This property can be directly employed into bioimaging HeLa cells. The cell toxicity (3-[4,5-dimethylthiazolyl-2]-2,5-diphenyltetrazolium bromide, MTT) assay demonstrated that the silver nanocluster has only little affect on the cytotoxicity to the cells, which further proves the applicability of the method in tumor cell imaging. At last, the universality of the synthesis protocol is verified by using a series of other G-quadruplex sequences as templates. For a lot of functional nucleic acids, such as human telomeres and certain aptamers, are with G-rich sequences and can fold into G-quadruplexes in functioning conditions, our method displays a promising application space in future researches.Highlights► G-quadruplex stabilized silver nanoclusters were utilized as novel fluorescent probes for cell bioimaging. ► The characteristic of silver nanocluster were investigated using CD, MALDI TOF MS, and TEM analysis. ► The cell toxicity MTT assay demonstrated that the silver nanocluster has only little affect on the cytotoxicity.
Co-reporter:Jun Ai, Yuanhong Xu, Dan Li, Zuojia Liu, Erkang Wang
Talanta 2012 Volume 101() pp:32-37
Publication Date(Web):15 November 2012
DOI:10.1016/j.talanta.2012.07.075
Herein, folic acid (FA) conjugated with AuNPs were introduced into the cancer cell imaging via the specific interaction between FA and the folate receptor on the cell surface. FA protected gold nanoparticles (AuNPs) was synthesized and labeled with fluorescein isothiocynate (FITC) to form the FITC–FA–AuNPs (FFANPs). As over-expressed folic acid receptor in some cancer cells and folic acid can specifically and selectively combine, the FFANPs can bind to the FR expressed on tumor cells such as HeLa cells (human epithelial cervical cancer) and CERF-CEM cells (T cell line, human acute lymphoblastic leukemia). As a result, cancer cell imaging can be achieved. To ascertain the FR target ability, it has been acquired by FR-targeted images using synthetic FFANPs. The formation of FITC–FA can be identified by MS. FCM was carried out to study the cell uptake of FFANPs. The cell toxicity (3-[4,5–dimethylthiazolyl–2]−2, 5-diphenyltetrazolium bromide, MTT) assay demonstrated that the FITC-labeled conjugate had only little effect on the cytotoxicity to the cells, which further proved the applicability of the method in tumor cell imaging.Highlights► FA protected AuNPs labeled with FITC to form the FFANPs. ► FFANPs can bind to the FR expressed on tumor cells. ► The FFANPs have only little affect on the cytotoxicity.
Co-reporter:Bingyan Han
Analytical and Bioanalytical Chemistry 2012 Volume 402( Issue 1) pp:129-138
Publication Date(Web):2012 January
DOI:10.1007/s00216-011-5307-6
In this review, we discuss the synthesis and applications of DNA-templated fluorescent silver nanoclusters in aqueous solution. Various oligonucleotide sequences or conformations have been utilized to synthesize silver nanoclusters with excellent fluorescence properties. The range of applications has expanded greatly, from live cell staining and the detection of metal ions and small biomolecules to the detection of DNA or proteins.
Co-reporter:Jiangtao Ren, Jiahai Wang, Jin Wang, Nathan W. Luedtke, Erkang Wang
Biosensors and Bioelectronics 2012 Volume 35(Issue 1) pp:401-406
Publication Date(Web):15 May 2012
DOI:10.1016/j.bios.2012.03.028
In this work, a simple and label-free fluorescent method via fluorescent indicator displacement (FID) was proposed for enantioselectively determining d-enantiomer of arginine vasopressin (DV) using DV-specific DNA aptamer (V-apt) and one guanidiniophthalocyanine dye (Zn-DIGP). Zn-DIGP that preferentially binds to single-stranded DNA with fluorescence enhancement rather than duplexes occupies the long internal loop of V-apt and generates intensive fluorescence. Then DV is introduced into the solution containing Zn-DIGP and V-apt, and displaces the Zn-DIGP from the binding site of internal loop, leading to fluorescence decrease. But l-enantiomer cannot induce any fluorescence change due to the selectivity of V-apt. This established FID technique can detect DV with a detection limit of 100 nM and exhibits a broad linear range, and is able to discriminate enantiomers of arginine vasopressin unambiguously. Moreover chiral separation by chromatography, complicated experimental procedures and covalent modification of tags (such as organic dyes, redox-active metal complexes) are avoided in our strategy. This simple and label-free method is promising for fabricating diverse aptasensors to determine other biomolecules and drugs.Highlights► Enantioselectively detection of d-oligopeptide was realized by fluorescent method. ► d-Enantiomer-specific DNA aptamer was utilized as the chiral selector. ► The mechanism is based on fluorescent indicator displacement (FID). ► The FID method is label-free, very simple and cost-effective.
Co-reporter:Jiangtao Ren, Jiahai Wang, Jin Wang, Nathan W. Luedtke, Erkang Wang
Biosensors and Bioelectronics 2012 Volume 31(Issue 1) pp:316-322
Publication Date(Web):15 January 2012
DOI:10.1016/j.bios.2011.10.038
In recent years, bioanalytical technology based on G-quadruplex has been paid significant attention due to its versatility and stimulus-responsive reconfiguration. Notwithstanding, several key issues for template-directed reassembly of G-quadruplex have not been resolved: what is the key factor for determining the sensitivity and selectivity of split G-quadruplex probes toward target DNA. Therefore, in this study, we designed three pairs of split G-quadruplex probes and investigated the sensitivity and selectivity of these systems in terms of potassium ion concentration and split modes of G-quadruplex. Due to its simplicity and sensitivity, N-methyl-mesoporphyrin (NMM) as fluorescence probes was used to monitor the target-directed reassembling process of G-quadruplex. A G-quadruplex sequence derived from the c-Myc promoter was split into “symmetric” probes, where each fragment contained two runs of guanine residues (2 + 2), or into “asymmetric” fragments each containing (3 + 1 or 1 + 3) runs of guanine residues. In all three cases, the sensitivity of target detection was highly dependent on the thermodynamic stability of the hybrid structure, which can be modulated by potassium ion concentrations. Using a combination of CD, fluorescence, and UV spectroscopy, we found that increasing potassium concentrations can increase the sensitivity of target detection, but can decrease the selectivity of discriminating cognate versus mismatched “target” DNA. The previous argument that asymmetrically split probes were always better than symmetrically split probes in terms of selectivity was not plausible anymore. These results demonstrate how the sensitivities and selectivity of split probes to mutations can be optimized by tuning the thermodynamic stability of the three-way junction complex.Highlights► Three split probe designs of G-quadruplex using fluorescence were studied. ► Potassium ion is critical in the stability of hybrids of split probes and target DNA. ► The stability of hybrid decides the sensitivity and selectivity of each design. ► Symmetrically split G-quadruplex is more favorable for single mismatch discrimination.
Co-reporter:Shaojun Guo and Erkang Wang
Accounts of Chemical Research 2011 Volume 44(Issue 7) pp:491
Publication Date(Web):May 25, 2011
DOI:10.1021/ar200001m
In order to develop new, high technology devices for a variety of applications, researchers would like to better control the structure and function of micro/nanomaterials through an understanding of the role of size, shape, architecture, composition, hybridization, molecular engineering, assembly, and microstructure. However, researchers continue to face great challenges in the construction of well-defined micro/nanomaterials with diverse morphologies. At the same time, the research interface where micro/nanomaterials meet electrochemistry, analytical chemistry, biomedicine, and other fields provides rich opportunities to reveal new chemical, physical, and biological properties of micro/nanomaterials and to uncover many new functions and applications of these materials.In this Account, we describe our recent progress in the construction of novel inorganic and polymer nanostructures formed through different simple strategies. Our synthetic strategies include wet-chemical and electrochemical methods for the controlled production of inorganic and polymer nanomaterials with well-defined morphologies. These methods are both facile and reliable, allowing us to produce high-quality micro/nanostructures, such as nanoplates, micro/nanoflowers, monodisperse micro/nanoparticles, nanowires, nanobelts, and polyhedron and even diverse hybrid structures. We implemented a series of approaches to address the challenges in the preparation of new functional micro/nanomaterials for a variety of important applicationsThis Account also highlights new or enhanced applications of certain micro/nanomaterials in sensing applications. We singled out analytical techniques that take advantage of particular properties of micro/nanomaterials. Then by rationally tailoring experimental parameters, we readily and selectively obtained different types of micro/nanomaterials with novel morphologies with high performance in applications such as electrochemical sensors, electrochemiluminescent sensors, gene delivery agents, and fuel cell catalysts. We expect that micro/nanomaterials with unique structural characteristics, properties, and functions will attract increasing research interest and will lead to new opportunities in various fields of research.
Co-reporter:Wen Ren, Shaojun Guo, Shaojun Dong and Erkang Wang
Nanoscale 2011 vol. 3(Issue 5) pp:2241-2246
Publication Date(Web):08 Apr 2011
DOI:10.1039/C1NR10074B
A facile, low-cost and templateless wet-chemical method was reported for the mass synthesis of Ag dendrites with rod-like tips which were characterized by various methods. The columniform tips protruded in random directions, of which the diameters were similar. A series of experiments were carried out to explore the effect of sodium citrate on the morphology of the obtained Ag nanostructures, and it was demonstrated that the concentration of sodium citrate was important for the formation of the cylindrical tips on the Ag dendrites. A possible mechanism was proposed to explain the role of sodium citrate in the synthesis of Ag dendrites with rod-like tips. Based on the roughness caused by the Ag dendrites, a superhydrophobic surface was fabricated in a simple procedure on a glass substrate, and the contact angle of the surface was as high as 156.4°. According to similar procedures, superhydrophobic surfaces were easily attained on a DVD disc and commercial aluminium foil, indicating the as-prepared Ag dendrites can be used to fabricate superhydrophobic surfaces on various smooth substrates.
Co-reporter:Zhijun Guo, Jiahai Wang, Jiangtao Ren and Erkang Wang
Nanoscale 2011 vol. 3(Issue 9) pp:3767-3773
Publication Date(Web):08 Aug 2011
DOI:10.1039/C1NR10434A
Ion current through a nascent nanochannel with conically shaped geometry in PET (polyethylene terephthalate) membrane sandwiched between two same buffer solutions at pH ≤ 3 was routinely considered to exhibit no rectification and, if any, much weaker rectification than that for a nanochannel with a negative surface charge, since the surface charge on the membrane decreases to zero along with decreasing the pH value of the buffer solution down to the pKa of carboxylic acid. However, in this study, we discovered that in the buffer solution with low ionic strength at pH values below 3, the conically shaped nanochannels exhibited distinct ion current rectification, as expected for nanochannels with a positive surface charge, if voltages beyond ±2V range were scanned. We reasoned that the current rectification engendered by the positive surface charge of a conical nanochannel was due to further protonation of the hydrogen bonded hydrogel layer or neutral carboxylic acid inside the nanochannel. Therefore, our results enrich the knowledge about nanochannel technology and indicate that a nanofluidic diode based on pH-reversed ion current rectification through a conical nanochannel can be achieved without any modification of the PET membrane.
Co-reporter:Libing Zhang, Bingyan Han, Tao Li and Erkang Wang
Chemical Communications 2011 vol. 47(Issue 11) pp:3099-3101
Publication Date(Web):24 Jan 2011
DOI:10.1039/C0CC04523C
We developed a label-free fluorescent Pb2+ sensor utilizing a DNAzyme-based fluorescing molecular switch, which enables fluorescence detection of Pb2+ in aqueous solution with high sensitivity and selectivity.
Co-reporter:Yinan Qin, Lei Xu, Jiangtao Ren, Yaqing Liu and Erkang Wang
Chemical Communications 2011 vol. 47(Issue 29) pp:8232-8234
Publication Date(Web):21 Jun 2011
DOI:10.1039/C1CC11993A
Three kinds of redox-mediated behavior were realized at an azobenzene-functionalized electrode, which has great potential for application in the field of molecular devices. According to these results, the functionalized electrode could act as either a cathodic molecular rectifier or anodic molecular rectifier.
Co-reporter:Xuan Yang, Yan Du, Dan Li, Zhaozi Lv and Erkang Wang
Chemical Communications 2011 vol. 47(Issue 38) pp:10581-10583
Publication Date(Web):21 Apr 2011
DOI:10.1039/C1CC11374G
A new kind of silver micro-dendrites have been synthesized for the separation and multiplex detection of DNA merely by earth gravity. Through this approach, the DNA strands of the sickle cell disease, human T-lymphotropic virus type I, the anthrax lethal factor can be detected down to 100 pM with the detection range from 100 pM to 100 nM at the same time.
Co-reporter:Weiwei Guo, Jipei Yuan and Erkang Wang
Chemical Communications 2011 vol. 47(Issue 39) pp:10930-10932
Publication Date(Web):12 Sep 2011
DOI:10.1039/C1CC11921D
The fluorescence (FL)“off–on” switching of designed DNA duplex stabilized silver nanoclusters can be accomplished through the control of DNA strand exchange reaction. The successful sequential control of the FL emission of silver nanoclusters in “off–on” switching cycles confirms that the DNA duplex stabilized silver nanoclusters can work as a new kind of DNA FL switch.
Co-reporter:Jiangtao Ren, Jiahai Wang, Lei Han, Erkang Wang and Jin Wang
Chemical Communications 2011 vol. 47(Issue 38) pp:10563-10565
Publication Date(Web):22 Aug 2011
DOI:10.1039/C1CC13973H
Kinetically grafting G-quadruplexes onto one-dimensional DNA nanostructures with precise positioning was realized in this study. The programs hold great promise for label-free and enzyme-free detection of various targets as a result of signal amplification from G-quadruplexes, and building DNA nanostructures as scaffolds due to the molecular recognition capacity of G-quadruplex aptamers.
Co-reporter:Libing Zhang, Jinbo Zhu, Tao Li, and Erkang Wang
Analytical Chemistry 2011 Volume 83(Issue 23) pp:8871
Publication Date(Web):October 21, 2011
DOI:10.1021/ac2006763
A label-free bifunctional colorimetric oligonucleotide probe for DNA and protein detection has been developed on the basis of a novel catalytic molecular beacon consisting of two hairpin structures and a split G-quadruplex DNAzyme in the middle. The two loops of this molecular beacon consist of thrombin aptamer sequence and the complementary sequence of target DNA, which are utilized to sense single-stranded DNA and thrombin. The G-quadruplex DNAzyme can effectively catalyze the H2O2-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine sulfate to generate colorimetric signal. Upon addition of the target, the DNA or protein combines with one loop of the hairpin structures, and meanwhile drives the middle G-quadruplex DNAzyme to dissociate. This results in a decrease of catalytic activity, enabling the separate analysis of DNA and thrombin.
Co-reporter:Shaojun Guo, Yan Du, Xuan Yang, Shaojun Dong, and Erkang Wang
Analytical Chemistry 2011 Volume 83(Issue 20) pp:8035
Publication Date(Web):September 12, 2011
DOI:10.1021/ac2019552
Taking advantage of strand-displacement DNA polymerization and parallel-motif DNA triplex system as dual amplifications, a new electrochemical label-free integrated aptasensor based on silver microspheres (SMSs) as a separation element and graphene-mesoporous silica–gold nanoparticle (NP) hybrids (GSGHs) as an enhanced element of the sensing platform was first reported. In this sensing design (schematic representation of the sensing procedure for adenosine triphosphate detection, Scheme 1 in manuscript text), which contains an enhanced three-step magnification process, SMSs with “clean” surface were first used to separate the undesirable aptamer and aptamer–adenosine triphosphate (ATP) complex attached on SMSs surface after aptamer–ATP interaction, which lead to the detachment of blocker DNA into the solution phase. Then, under the assistance of blocker DNA, an amplified method based on the inherent signal-transduction mechanism of the hairpin probe and strand-displacement property of DNA polymerase was introduced. The obtained duplex DNA was used to hybridize with an acceptor DNA assembled on electrode to form triplex DNA, which could bring a more obvious detection signal compared with the duplex DNA without the amplification. The electrochemical signal came from the GSGH-based enhanced sensing interface containing positively charged ferrocene-appended poly(ethyleneimine) (Fc-PEI). Using the above multiple effects, we could achieve the sensitive analysis of a model small molecule–ATP (an important “molecular currency” of intracellular energy transfer) in a wide detection range from 0.05 nM to 56.5 nM with the detection limit of 0.023 nM.
Co-reporter:Xuan Yang and Erkang Wang
Analytical Chemistry 2011 Volume 83(Issue 12) pp:5005
Publication Date(Web):May 17, 2011
DOI:10.1021/ac2008465
A novel nanoparticle autocatalytic sensor for the detection of Ag+ and Cu2+ has been constructed based on the oxidative ability of Ag+ and Cu2+ toward o-phenylenediamine (OPDA). Ag+ and Cu2+ can be reduced to zerovalent silver and copper, respectively, and then such zerovalent Ag and Cu species form silver and copper nanoparticles that can catalyze the reaction between OPDA and Ag+ and Cu2+. In the reaction, OPDA is oxidized to 2,3-diaminophenazine (OPDAox), which has a fluorescence emission at 568 nm. Under the optimal conditions, Ag+ and Cu2+ can be detected in the concentration ranges from 60 nM to 60 μM and from 2.5 nM to 25 μM, respectively. Through this facile approach, Ag+ and Cu2+ can be detected down to 60 nM and 2.5 nM, respectively. In addition, the sensor is utilized for the detection of Ag+ and Cu2+ in sewage, and we have obtained very good results that are consistent with those of inductively coupled plasma–mass spectroscopy (ICP-MS). Moreover, such a nanoparticle autocatalytic sensor is applied to test paper for the detection of Ag+ and Cu2+ with the naked eye. With such test paper, Ag+ and Cu2+ could be detected at levels as low as 0.06 nmol and 0.3 nmol, respectively, with detection ranges of 0.06–60 nmol for Ag+ and 0.3–60 nmol for Cu2+, under the irradiation of UV light (365 nm). The test paper could be potentially used in the rapid detection of Ag+ and Cu2+ in real samples.
Co-reporter:Yan Du, Chaogui Chen, Ming Zhou, Shaojun Dong, and Erkang Wang
Analytical Chemistry 2011 Volume 83(Issue 5) pp:1523
Publication Date(Web):February 3, 2011
DOI:10.1021/ac101988n
Aptamers are artificial oligonucleotides that have been widely employed to design biosensors (i.e., aptasensors). In this work, we report a microfluidic electrochemical aptamer-based sensor (MECAS) by constructing Au−Ag dual-metal array three-electrode on-chip for multiplex detection of small molecules. In combination with the microfluidic channels covering on the glass chip, different targets are transported to the Au electrodes integrated on different positions of the chip. These electrodes are premodified by different kinds of aptamers, respectively, to fabricate different sensing interfaces which can selectively capture the corresponding target. It is an address-dependent sensing platform; thus, with the use of only one electrochemical probe, multitargets can be recognized and detected according to the readout on a corresponding aptamer-modified electrode. In the sensing strategy, the electrochemical probe, [Ru(NH3)6]3+ (RuHex), which can quantitatively bind to surface-confined DNA via electrostatic interaction, was used to produce chronocoulometric signal; Au nanoparticles (AuNPs) were used to improve the sensitivity of the sensor by amplifying the detection signals. Moreover, the sensing interface fabrication, sample incubation, and electrochemical detection were all performed in microfluidic channels. By using this detection chip, we achieved the multianalysis of two model small molecules, ATP, and cocaine, in mixed samples within 40 min. The detection limit of ATP was 3 × 10−10 M, whereas the detection limit of cocaine was 7 × 10−8 M. This Au−Ag dual metal electrochemical chip detector integrated MECAS was simple, sensitive, and selective. Also it is similar to a dosimeter which accumulates signal upon exposure. It held promising potential for designing electrochemical devices with high throughput, high automation, and high integration in multianalysis.
Co-reporter:Jipei Yuan, Weiwei Guo, Erkang Wang
Analytica Chimica Acta 2011 Volume 706(Issue 2) pp:338-342
Publication Date(Web):14 November 2011
DOI:10.1016/j.aca.2011.08.043
In this work, oligonucleotide stabilized silver nanoclusters as novel fluorescent probes were successfully utilized for the drug–DNA interaction study. Silver nanoclusters were proved to be sensitive probes for the drugs investigated (including of two kinds of intercalators, daunorubicin and quinacrine, as well as a non-intercalating binder bisBenzimide H 33258), as the detection limits at 10−8 mol L−1 level of studied drugs can be achieved. The interactions of drugs and calf thymus DNA were investigated using non-linear fit analysis, and the binding constants as well as binding site sizes were obtained. As biocompatible materials, silver nanoclusters are promising in the chemical especially biochemical analysis fields.Graphical abstractIn this work, oligonucleotide stabilized silver nanoclusters as novel fluorescent probes were successfully utilized for the drug–DNA interaction study. With the advantage of biocompatibility and simple synthesis procedure, Ag clusters are promising fluorescent probes in the chemical and especially biochemical sensing fields.Highlights► Oligonucleotide stabilized silver nanoclusters were utilized as novel fluorescent probes for drug–DNA interaction. ► The binding constants and binding site sizes of drug–DNA interactions were investigated using non-linear fit analysis. ► Sequence preference between daunorubicin and six double-stranded tetranucleotides was studied.
Co-reporter:Yan Du, Bingling Li, Shaojun Guo, Zhixue Zhou, Ming Zhou, Erkang Wang and Shaojun Dong
Analyst 2011 vol. 136(Issue 3) pp:493-497
Publication Date(Web):16 Nov 2010
DOI:10.1039/C0AN00557F
The appearance of the aptamer provides good recognition elements for small molecules, especially for drugs. In this work, by combining the advantages of magnetic nanoparticles (MNPs) with colorimetric drug detection using hemin-G-quadruplex complex as the sensing element, we report a simple and sensitive DNAzyme-based colorimetric sensor for cocaine detection in a 3,3,5,5-tetramethylbenzidine sulfate (TMB)–H2O2 reaction system. The whole experimental processes are simplified. Cocaine aptamer fragments, SH–C2, are covalently labeled onto the amine-functionalized MNPs. When the target cocaine and another cocaine aptamer fragments (C1) grafted with G-riched strand AG4 (i.e. C1–AG4) are present simultaneously, the C2 layer on MNPs hybridizes partly with C1–AG4 to bind the cocaine. The C1–AG4 can be combinded with hemin to form DNAzyme which can effectively catalyze the H2O2-mediated oxidation of TMB, giving rise to a change in solution color. Importantly, using MNPs as the separation and amplification elements could effectively reduce the background signal and the interference from the real samples. A linear response from 0.1 μM to 20 μM is obtained for cocaine and a detection limit of 50 nM is achieved, which provides high sensitivity and selectivity to detect cocaine.
Co-reporter:Xuan Yang, Zhaozi Lv, Erkang Wang, Xuping Sun
Journal of Electroanalytical Chemistry 2011 Volume 656(1–2) pp:17-22
Publication Date(Web):15 June 2011
DOI:10.1016/j.jelechem.2011.01.038
In this paper we report on the electrodeposition-based construction of film of nano-roughened, hierarchical Au microstructures on indium tin oxide (ITO) surface in a controllable manner. It is found that both the nanotexture and the size of such microstructures can be simply controlled by varying the concentration of Au composition or the deposition potential used. Study on time-evolved microstructure growth further reveals that both the size of the microstructures and the surface coverage of the substrate can be tuned in a continuous mode. It is also found that such Au film exhibits high catalytic activity towards the oxidation of H2O2.Highlights► We report on the construction of Au microstructures on indium tin oxide surface. ► The microstructures can be controlled by varying the concentration of Au composition. ► The microstructures can be controlled by varying the deposition potential. ► The microstrutures and the surface coverage of substrate can be tuned continuously. ► Such Au film exhibits high catalytic activity towards the oxidation of H2O2.
Co-reporter:Chunhe Li, Erkang Wang, Jin Wang
Chemical Physics Letters 2011 Volume 505(1–3) pp:75-80
Publication Date(Web):21 March 2011
DOI:10.1016/j.cplett.2011.02.020
Abstract
We develop a theoretical framework for exploring global natures of non-equilibrium dynamical systems under intrinsic statistical fluctuations. We found the underlying driving force can be decomposed into three terms: gradient of potential landscape, curl probability flux, inhomogeneity of diffusion. We studied a limit cycle oscillation model and found that the potential landscape has a Mexican hat close ring valley shape and attracts the system down to the ring while the curl probability flux on the ring drives the coherent oscillation. The barrier heights characterizing the landscape topography provide a quantitative measure for global stability of non-equilibrium dynamical systems.
Co-reporter:Linfeng Sheng, Jiangtao Ren, Yuqing Miao, Jiahai Wang, Erkang Wang
Biosensors and Bioelectronics 2011 Volume 26(Issue 8) pp:3494-3499
Publication Date(Web):15 April 2011
DOI:10.1016/j.bios.2011.01.032
In this paper, we developed a simple method to detect fungi toxin (ochratoxin A) produced by Aspergillus Ochraceus and Penicillium verrucosumm, utilizing graphene oxide as quencher which can quench the fluorescence of FAM (carboxyfluorescein) attached to toxin-specific aptamer. By optimizing the experimental conditions, we obtained the detection limit of our sensing platform based on bare graphene oxide to be 1.9 μM with a linear detection range from 2 μM to 35 μM. Selectivity of this sensing platform has been carefully investigated; the results showed that this sensor specifically responded to ochratoxin A without interference from other structure analogues (N-acetyl-l-phenylalanine and warfarin) and with only limited interference from ochratoxin B. Experimental data showed that ochratoxin A as well as other structure analogues could adsorb onto the graphene oxide. As compared to the non-protected graphene oxide based biosensor, PVP-protected graphene oxide reveals much lower detection limit (21.8 nM) by two orders of magnitude under the optimized ratio of graphene oxide to PVP concentration. This sensor has also been challenged by testing 1% red wine containing buffer solution spiked with a series of concentration of ochratoxin A.
Co-reporter:Shaojun Guo, Dan Wen, Yueming Zhai, Shaojun Dong, Erkang Wang
Biosensors and Bioelectronics 2011 Volume 26(Issue 8) pp:3475-3481
Publication Date(Web):15 April 2011
DOI:10.1016/j.bios.2011.01.028
Trinitrotoluene, usually known as TNT, is a kind of chemical explosive with hazardous and toxic effects on the environment and human health. Ever-increasing needs for a secure society and green environment essentially require the detection of TNT with rapidity, high sensitivity and low cost. In this article, ionic liquid–graphene hybrid nanosheets (IL–GNs) have been used as an enhanced material for rapidly electrochemical detection of trinitrotoluene (TNT). IL–GNs were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray photo-electron spectroscopy, electrochemical impedance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, which confirmed that IL has been effectively functionalized on the surface of GNs. Significantly, IL–GNs modified glassy carbon electrode (GCE) showed 6.2 and 51.4-folds higher current signals for TNT reduction than IL–CNTs/GCE and bare GCE, respectively. Adsorptive stripping voltammetry (ASV) for the detection of TNT on IL–GNs exhibited a good linear range from 0.03 to 1.5 ppm with a detection limit of 4 ppb on the basis of the signal-to-noise characteristics (S/N = 3). Moreover, IL–GNs/GCE exhibited good stability and reproducibility for the detection of TNT. And, IL–GNs based electrochemical detection platform was also successfully demonstrated for the detection of TNT in ground water, tap water, and lake water with satisfactory results.
Co-reporter:Zhijun Guo, Jiangtao Ren, Jiahai Wang, Erkang Wang
Talanta 2011 Volume 85(Issue 5) pp:2517-2521
Publication Date(Web):15 October 2011
DOI:10.1016/j.talanta.2011.08.015
Ochratoxin A, a toxin produced by Aspergillus ochraceus and Penicillium verrucosum, is one of the most abundant food-contaminating mycotoxins in the world. It has been classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen. In this paper, a sensitive and selective fluorescent aptasensor for ochratoxin A (OTA) detection was constructed, utilizing single-walled carbon nanotubes (SWNTs) as quencher which can quench the fluorescence of free unfolded toxin-specific aptamer attached with FAM (carboxyfluorescein). Without any coating materials as compared to graphene-oxide based sensor, we obtained the detection limit of our sensing platform based on SWNTs to be 24.1 nM with a linear detection range from 25 nM to 200 nM. This technique responded specifically to OTA without interference from other analogues (N-acetyl-l-phenylalanine, warfarin and OTB). It has also been verified for real sample application by testing 1% beer containing buffer solution spiked with a series of concentration of OTA.Highlights► Single-walled carbon nanotubes in combination with aptamer can detect ochratoxin A. ► Ochratoxin A induces the switching of the aptamer to antiparallel G-quadruplex. ► The G-quadruplex cannot be wrapped onto the single-walled carbon nanotubes. ► Low concentration of ochratoxin A can be detected without any coating materials.
Co-reporter:Shaojun Guo, Erkang Wang
Nano Today 2011 Volume 6(Issue 3) pp:240-264
Publication Date(Web):June 2011
DOI:10.1016/j.nantod.2011.04.007
Nobel metal nanomaterials (NMNs) with interesting physical and chemical properties are ideal building blocks for engineering and tailoring nanoscale structures for specific technological applications. Particularly, effectively controlling the size, shape, architecture, composition, hybrid and microstructure of NMNs plays an important role on revealing their new or enhanced functions and application potentials such as fuel cell and analytical sensors. This review article focuses on recent advances on controllable synthesis and fuel cell and sensing applications of NMNs. First, recent contributions on developing a wet-chemical approach for the controllable synthesis of noble metal nanomaterials with a rich variety of shapes, e.g. single-component Pt, Pd, Ag and Au nanomaterials, multi-component core/shell, intermetallic or alloyed nanomaterials, metal fluorescent nanoclusters and metal nanoparticles-based hybrid nanomaterials, are summarized. Then diversified approaches to different types of NMNs-based nanoelectrocatalysts with the aim to enhance their activity and durability for fuel cell reactions are outlined. The review next introduces some exciting push in the use of NMNs as enhanced materials or reporters or labels for developing new analytical sensors including electrochemical, colorimetric and fluorescent sensors. Finally, we conclude with a look at the future challenges and prospects of the development of NMNs.Graphical abstractHighlights► New developments in the controllable synthesis of metal nanomaterials are summarized. ► Designing new nanoelectrocatalysts with high activity and durability is outlined. ► Some exciting pushes in metal nanomaterials-based sensing applications are introduced. ► Future challenges and prospects of the development of metal nanomaterials are concluded.
Co-reporter:Wen Ren;JiYang Liu;ShaoJun Guo
Science China Chemistry 2011 Volume 54( Issue 8) pp:
Publication Date(Web):2011 August
DOI:10.1007/s11426-011-4312-0
A label-free and low-cost mapping method based on SERS imaging was reported for illustrating the distribution of phospholipids with similar structures in binary lipid membranes on Ag nanoparticles (Ag NPs) films. The Ag NPs films exhibited strong SERS activity and good reproducibility which were investigated with p-aminothiophenol (p-ATP) as probe molecules. Atomic force microscope (AFM) measurement proved that compact lipid membranes formed on the Ag NPs films. Basing on the Ag NPs films, the SERS spectra of phospholipids in the mixed lipid membranes were achieved and the inherent vibration of 1,2-dimyristoyl-sn-lycero-3-phosphoglycerol, sodium salt (DMPG), 1482 cm−1, was used to distinguish between DMPG and dimyristoylphosphatidylcholine (DMPC). The proportions of phospholipids in the mixed lipid membranes were represented by the intensity ratio of peaks at 1482 cm−1 and 1650 cm−1 (R1482/1650) simultaneously: increasing R1482/1650 indicated higher proportion of DMPG and lower proportion of DMPC. SERS imaging of the lipid membranes was constructed as a combination of spacial information and the semiquantitative detection of phospholipids according to R1482/1650, which showed that the charged phospholipids, DMPG, aggregated in the hybrid lipid membranes. The presented mapping strategy based on SERS imaging carried out on Ag NPs films supplied a facile, label-free and inexpensive way for potential applications in the research on the structure of the lipid membrane, such as lipid domains and rafts.
Co-reporter:Jiangtao Ren;Haixia Qin;Jiahai Wang
Analytical and Bioanalytical Chemistry 2011 Volume 399( Issue 8) pp:2763-2770
Publication Date(Web):2011 March
DOI:10.1007/s00216-011-4669-0
In this study we have used two fluorescent probes, tetrakis(diisopropylguanidino)-zinc-phthalocyanine (Zn-DIGP) and N-methylmesoporphyrin IX (NMM), to monitor the reassembly of “split” G-quadruplex probes on hybridization with an arbitrary “target” DNA. According to this approach, each split probe is designed to contain half of a G-quadruplex-forming sequence fused to a variable sequence that is complementary to the target DNA. Upon mixing the individual components, both base-pairing interactions and G-quadruplex fragment reassembly result in a duplex–quadruplex three-way junction that can bind to fluorescent dyes in a G-quadruplex-specific way. The overall fluorescence intensities of the resulting complexes were dependent on the formation of proper base-pairing interactions in the duplex regions, and on the exact identity of the fluorescent probe. Compared with samples lacking any “target” DNA, the fluorescence intensities of Zn-DIGP-containing samples were lower, and the fluorescence intensities of NMM-containing samples were higher on addition of the target DNA. The resulting biosensors based on Zn-DIGP are therefore termed “turn-off” whereas the biosensors containing NMM are defined as “turn-on”. Both of these biosensors can detect target DNAs with a limit of detection in the nanomolar range, and can discriminate mismatched from perfectly matched target DNAs. In contrast with previous biosensors based on the peroxidase activity of heme-bound split G-quadruplex probes, the use of fluorescent dyes eliminates the need for unstable sensing components (H2O2, hemin, and ABTS). Our approach is direct, easy to conduct, and fully compatible with the detection of specific DNA sequences in biological fluids. Having two different types of probe was highly valuable in the context of applied studies, because Zn-DIGP was found to be compatible with samples containing both serum and urine whereas NMM was compatible with urine, but not with serum-containing samples.
Co-reporter:Jin Wang;Kun Zhang;Li Xu
PNAS 2011 Volume 108 (Issue 20 ) pp:8257-8262
Publication Date(Web):2011-05-17
DOI:10.1073/pnas.1017017108
We developed a theoretical framework to prove the existence and quantify the Waddington landscape as well as chreode-biological
paths for development and differentiation. The cells can have states with the higher probability ones giving the different
cell types. Different cell types correspond to different basins of attractions of the probability landscape. We study how
the cells develop from undifferentiated cells to differentiated cells from landscape perspectives. We quantified the Waddington
landscape through construction of underlying probability landscape for cell development. We show the developmental process
proceeds as moving from undifferentiated to the differentiated basins of attractions. The barrier height of the basins of
attractions correlates with the escape time that determines the stability of cell types. We show that the developmental process
can be quantitatively described and uncovered by the biological paths on the quantified Waddington landscape from undifferentiated
to the differentiated cells. We found the dynamics of the developmental process is controlled by a combination of the gradient
and curl force on the landscape. The biological paths often do not follow the steepest descent path on the landscape. The
landscape framework also quantifies the possibility of reverse differentiation process such as cell reprogramming from differentiated
cells back to the original stem cell. We show that the biological path of reverse differentiation is irreversible and different
from the one for differentiation process. We found that the developmental process described by the underlying landscape and
the associated biological paths is relatively stable and robust against the influences of environmental perturbations.
Co-reporter:Yan Du, Shaojun Guo, Shaojun Dong, Erkang Wang
Biomaterials 2011 32(33) pp: 8584-8592
Publication Date(Web):
DOI:10.1016/j.biomaterials.2011.07.091
Co-reporter:Jinbo Zhu, Tao Li, Libing Zhang, Shaojun Dong, Erkang Wang
Biomaterials 2011 32(30) pp: 7318-7324
Publication Date(Web):
DOI:10.1016/j.biomaterials.2011.06.040
Co-reporter:Hui Wei
Luminescence 2011 Volume 26( Issue 2) pp:77-85
Publication Date(Web):
DOI:10.1002/bio.1279
ABSTRACT
Electrochemiluminescence (ECL) of tris(2,2’-bipyridyl)ruthenium(II) [Ru(bpy)32+] is an active research area and includes the synthesis of ECL-active materials, mechanistic studies and broad applications. Extensive research has been focused on this area, due to its scientific and practical importance. In this mini-review we focus on the bio-related applications of ECL. After a brief introduction to Ru(bpy)32+ ECL and its mechanisms, its application in constructing an effective bioassay is discussed in detail. Three types of ECL assay are covered: DNA, immunoassay and functional nucleic acid sensors. Finally, future directions for these assays are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Tao Li, Libing Zhang, Jun Ai, Shaojun Dong, and Erkang Wang
ACS Nano 2011 Volume 5(Issue 8) pp:6334
Publication Date(Web):July 6, 2011
DOI:10.1021/nn201407h
A novel kind of versatile logic device has been constructed utilizing ion-tuned DNA/Ag fluorescent nanoclusters, with K+ and H+ as two inputs. A well-chosen hairpin DNA with a poly-C loop serves as the template for synthesizing two species of Ag nanoclusters. Several G-tracts and C-tracts on its two terminals enable the hairpin DNA to convert into the G-quadruplex and/or i-motif structures upon input of K+ and H+. Such a structural change remarkably influences the spectral behaviors of Ag nanoclusters. In particular, different species of Ag nanoclusters have distinct fluorescence responses to the input of K+ and H+. These unique features of DNA/Ag nanoclusters enable multiple logic operations via multichannel fluorescence output, indicating the versatility as a molecular logic device. By altering the specific sequence of the hairpin DNA, more logic gates can be constructed utilizing Ag nanoclusters.Keywords: DNA structural change; DNA/Ag nanoclusters; fluorescence spectrum; logic gates
Co-reporter:Wen Ren, Youxing Fang, and Erkang Wang
ACS Nano 2011 Volume 5(Issue 8) pp:6425
Publication Date(Web):July 1, 2011
DOI:10.1021/nn201606r
Herein graphene oxide/Ag nanoparticle hybrids (GO/PDDA/AgNPs) were fabricated according to a self-assembly procedure. Using the obtained GO/PDDA/AgNPs as SERS substrates, an ultrasensitive and label-free detection of folic acid in water and serum was demonstrated based on the inherent SERS spectra of folic acid. The modified graphene oxide exhibited strong enrichment of folic acid due to the electrostatic interaction, and the self-assembled Ag nanoparticles greatly enhanced the SERS spectra of folic acid, both of which led to an ultrahigh sensitivity. Therefore, although the SERS enhancement of p-ATP on GO/PDDA/AgNPs was weaker than that on Ag nanoparticles, the SERS signals of folic acid on GO/PDDA/AgNPs were much stronger than that on Ag nanoparticles. To improve the detection, the concentration of GO/PDDA/AgNPs was optimized to reduce background of the graphene oxide. The SERS spectra of the folic acid showed that the minimum detected concentration of folic acid in water was as low as 9 nM with a linear response range from 9 to 180 nM. To estimate the feasibility of the detection method based on GO/PDDA/AgNPs for the practical applications, diluted serum containing different concentrations of folic acid was taken as real samples. It was established that the sensitivity and the linear range for the folic acid in serum were comparable to that in water. This ultrasensitive and label-free SERS detection of folic acid based on GO/PDDA/AgNPs offers great potential for practical applications of medicine and biotechnology.Keywords: folic acid; graphene oxide/Ag nanoparticle hybrids; SERS detection; serum
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
Energy & Environmental Science 2010 vol. 3(Issue 9) pp:1307-1310
Publication Date(Web):07 Jul 2010
DOI:10.1039/C0EE00053A
We demonstrate a wet-chemical strategy for synthesizing novel Pt/Pd bimetallic nanotubes with petal-like surfaces and controllable ultrathin Pd nanoshells, which exhibit significantly enhanced activity and stability towards ethanol electrooxidation.
Co-reporter:Shaojun Guo;Shaojun Dong
Advanced Materials 2010 Volume 22( Issue 11) pp:1269-1272
Publication Date(Web):
DOI:10.1002/adma.200903379
Co-reporter:Ming Zhou ; Yan Du ; Chaogui Chen ; Bingling Li ; Dan Wen ; Shaojun Dong
Journal of the American Chemical Society 2010 Volume 132(Issue 7) pp:2172-2174
Publication Date(Web):February 1, 2010
DOI:10.1021/ja910634e
This communication demonstrates for the first time the controlled power release of biofuel cells (BFCs) by aptamer logic systems processed according to the Boolean logic operations “programmed” into the biocomputing systems. On the basis of the built-in Boolean NAND logic, the fabricated aptamer-based BFCs logically controlled by biochemical signals enabled us to construct self-powered and intelligent logic aptasensors that can determine whether the two specific targets are both present in a sample.
Co-reporter:Tao Li ; Shaojun Dong
Journal of the American Chemical Society 2010 Volume 132(Issue 38) pp:13156-13157
Publication Date(Web):September 7, 2010
DOI:10.1021/ja105849m
A Pb2+-driven DNA molecular device which is constructed based on a DNA duplex−quadruplex exchange is utilized for the highly selective and sensitive detection of Pb2+. The power of this DNA device originates from the excellent efficiency of Pb2+ for stabilizing G-quadruplexes, which makes the DNA duplex unwind thereby driving the device. This device can be reset to the original state by addition of a strong Pb2+ chelator DOTA, endowing the device with good reusability. In the whole process, the signal readout is modulated via a fluorescent probe binding to and being released from the G-quadruplex. Such a DNA device can serve as a novel turn-on fluorescent sensor for Pb2+ detection with high selectivity and sensitivity.
Co-reporter:Gaiping Li, Junfeng Zhai, Dan Li, Xiaona Fang, Hong Jiang, Qingzhe Dong and Erkang Wang
Journal of Materials Chemistry A 2010 vol. 20(Issue 41) pp:9215-9219
Publication Date(Web):13 Sep 2010
DOI:10.1039/C0JM01776K
A facile one-pot method to prepare water-soluble, uniform-sized ZnS nanospheres (NSs) is reported. In the reaction, gradually decomposed thioacetamide (TAA) was used as the sulfur precursor, and cationic surfactant didodecyldimethylammonium bromide (DDAB) embedded with ferrocene (Fc) as the ligands for anions. The synthesized ZnS NSs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Wonderfully, the obtained ZnS NSs exhibited high performance in prohibiting the growth of Escherichia coli strain MG1655 (E. coli) and negligible mammalian cell toxicity, and these important features make it a promising antimicrobial agent for controlling implant-related infections.
Co-reporter:Libing Zhang, Tao Li, Bingling Li, Jing Li and Erkang Wang
Chemical Communications 2010 vol. 46(Issue 9) pp:1476-1478
Publication Date(Web):20 Jan 2010
DOI:10.1039/B921191H
Mercury ion (Hg2+) is able to specifically bind to the thymine–thymine (T–T) base pair in a DNA duplex and single-walled carbon nanotubes (SWNTs) can effectively quench fluorescence of the dye tethered to the DNA, which enables fluorescent detection of Hg2+ in aqueous solution with high selectivity and sensitivity.
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
Chemical Communications 2010 vol. 46(Issue 11) pp:1869-1871
Publication Date(Web):13 Jan 2010
DOI:10.1039/B922148D
We for the first time report a facile, wet-chemical strategy for the high-yield (∼100%) synthesis of ultralong Pt-on-Pd bimetallic nanowires (NWs) with the cores being Pd NWs and the shells being made of dendritic Pt, which exhibit high surface area and enhanced electrocatalytic activity towards methanol oxidation reaction.
Co-reporter:Xuan Yang, Xuping Sun, Zhaozi Lv, Weiwei Guo, Yan Du and Erkang Wang
Chemical Communications 2010 vol. 46(Issue 46) pp:8818-8820
Publication Date(Web):18 Oct 2010
DOI:10.1039/C0CC03280H
A new kind of silver micro-dendrites with no surfactants protected has been synthesized for the separation and detection of DNA merely by earth gravity as the density of silver is larger than that of water. Through this approach, the DNA of human T-lymphotropic virus type I (HTLV-I) can be detected down to 10 pM with the detection range from 10 pM to 100 nM.
Co-reporter:Liu Deng, Shaojun Guo, Zuojia Liu, Ming Zhou, Dan Li, Ling Liu, Gaiping Li, Erkang Wang and Shaojun Dong
Chemical Communications 2010 vol. 46(Issue 38) pp:7172-7174
Publication Date(Web):18 Aug 2010
DOI:10.1039/C0CC01371D
A significant increase (ca. 22-fold) in the electricity generation due to a Shewanella oneidensis MR-1 biofilm was observed in the presence of Fe3O4/Au nanocomposites.
Co-reporter:Yan Du, Chaogui Chen, Jianyuan Yin, Bingling Li, Ming Zhou, Shaojun Dong and Erkang Wang
Analytical Chemistry 2010 Volume 82(Issue 4) pp:1556
Publication Date(Web):January 22, 2010
DOI:10.1021/ac902566u
Aptamers, which are artificial oligonucleotides selected in vitro, have been employed to design novel biosensors (i.e., aptasensors). In this work, we first constructed a label-free electrochemical aptasensor introducing a probe immobilization technique by the use of a layer-by-layer (LBL) self-assembled multilayer with ferrocene−appended poly(ethyleneimine) (Fc−PEI) on an indium tin oxide (ITO) array electrode for detection of cocaine. The Fc−PEI and gold nanoparticles (AuNPs) were LBL assembled on the electrode surface via electrostatic interaction. Then, cocaine aptamer fragments, SH-C2, were covalently labeled onto the outermost AuNP layer. When the target cocaine and cocaine aptamer C1 were present simultaneously, the SH-C2 layer hybridized partly with C1 to bind the cocaine, which led to a decreased differential pulse voltammetry (DPV) signal of Fc−PEI. This DPV signal change could be used to sensitively detect cocaine with the lowest detectable concentration down to 0.1 μM and the detection range up to 38.8 μM, which falls in the the expected range for medical use of detecting drug abuse involving cocaine. Meanwhile, the sensor was specific to cocaine in complex biologic fluids such as human plasma, human saliva, etc. The sensing strategy had general applicability, and the detection of thrombin could also be realized, displayed a low detection limit, and exhibited worthiness to other analytes. The aptasensor based on the array electrode held promising potential for integration of the sensing ability in multianalysis for simultaneous detection.
Co-reporter:Haixia Qin, Jiangtao Ren, Jiahai Wang, Nathan W. Luedtke, and Erkang Wang
Analytical Chemistry 2010 Volume 82(Issue 19) pp:8356
Publication Date(Web):August 30, 2010
DOI:10.1021/ac101894b
A label-free detection of K+ was developed using G-quadruplex DNA (c-Myc) modulated fluorescence enhancement of tetrakis-(diisopropylguanidino) zinc phthalocyanine (Zn-DIGP). Upon the addition of increasing concentrations of potassium, a detection limit of 0.8 μM for K+ was easily achieved. Comparative titrations using sodium, lithium, ammonium, transition metal, or alkali earth salts revealed that the fluorescence enhancement was highly specific for potassium ions. This system has, for the first time, provided a means for detecting 40 μM of K+ even in the presence of a 3500-fold excess of Na+ ions.
Co-reporter:Tao Li, Erkang Wang, and Shaojun Dong
Analytical Chemistry 2010 Volume 82(Issue 18) pp:7576
Publication Date(Web):August 20, 2010
DOI:10.1021/ac1019446
Here we demonstrate an anionic porphyrin, protoporphyrin IX (PPIX), as a parallel G-quadruplex-specific fluorescent probe for monitoring DNA structural changes and utilize it to develop a DNA-based K+ sensor. The interactions of PPIX with different DNA structures in K+ or Na+ solution are investigated by using circular dichroism, fluorescence, and UV−vis spectroscopy. The observations reveal that PPIX has an ∼100-fold selectivity for parallel G-quadruplexes against duplexes and antiparallel G-quadruplexes. Meanwhile, the fluorescence intensity of PPIX increases by over 10-fold upon binding to parallel G-quadruplexes. On the basis of the selectivity and fluorescence property of PPIX, we introduce a facile, label-free approach to monitoring DNA structural changes via fluorescence signal readout that is tuned by PPIX binding and release. To illustrate it, we utilize PPIX and a G-rich DNA PS2.M to construct a fluorescent K+ sensor based on an antiparallel-to-parallel conformation transition of the G-quadruplex. PS2.M adopts an antiparallel quadruplex structure in Na+ solution, whereas it gradually converts into a parallel G-quadruplex upon addition of increasing K+. This conformational change is indicated by a sharp increase in the fluorescence intensity of PPIX, owing to the good ability of PPIX to discriminate parallel G-quadruplexes from antiparallel ones. Even in the presence of 100 mM Na+, such a “turn-on” fluorescent sensor can respond to low concentrations of K+, with a limit of detection (0.5 mM) for K+ analysis. In addition, this sensor exhibits a high selectivity for K+ over other common metal ions, which ensures its practical applications to real samples. These results reveal that PPIX is promising for use as a specific DNA structural probe in sensing applications.
Co-reporter:Tao Li, Erkang Wang and Shaojun Dong
Analytical Chemistry 2010 Volume 82(Issue 4) pp:1515
Publication Date(Web):January 22, 2010
DOI:10.1021/ac902638v
The lead ion (Pb2+) has been proven to induce a conformational change of K+-stabilized G-quadruplex DNAzyme and inhibit the peroxidase-like activity [Li, T.; Wang, E.; Dong, S. J. Am. Chem. Soc. 2009, 131, 15082−15083]. This provides a rationale for utilizing Pb2+-induced allosteric G-quadruplex DNAzyme to probe aqueous Pb2+. Here, we choose a common G-quadruplex DNAzyme named PS2.M to develop a novel Pb2+ sensor with two detection means: colorimetry and chemiluminescence (CL). In the presence of K+, PS2.M (with hemin as a cofactor) exhibits a superior DNAzyme activity and effectively catalyzes the H2O2-mediated oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) or luminol, which results in a color change or generates CL emission. Upon the addition of Pb2+, K+-stabilized PS2.M is induced to convert to the Pb2+-stabilized structure with higher stability but lower DNAzyme activity, which is reflected by an obvious increase in DNA melting temperature but a sharp decrease in readout signal. This allows us to utilize PS2.M for quantitative analysis of aqueous Pb2+ using the ABTS−H2O2 colorimetric system and luminol−H2O2 CL system. In each case, the readout signal is linearly dependent on the logarithm of Pb2+ concentration within a certain range. Nevertheless, two sensing systems provide different sensitivity for Pb2+ analysis. With colorimetry, Pb2+ can be detected at a level of 32 nM (∼7 ppb), whereas the detection limit of Pb2+ is 1 nM (0.2 ppb) when utilizing the CL method. In addition to high sensitivity, the above sensing systems exhibit good selectivity for Pb2+ over other metal ions. These results demonstrate the facility and effectivity of our introduced DNAzyme-based sensor for quantitative Pb2+ analysis.
Co-reporter:Ming Zhou, Chaogui Chen, Yan Du, Bingling Li, Dan Wen, Shaojun Dong and Erkang Wang
Lab on a Chip 2010 vol. 10(Issue 21) pp:2932-2936
Publication Date(Web):21 Sep 2010
DOI:10.1039/C0LC00009D
The development of microfluidic devices has been spurred by the desire to produce low-cost point-of-care diagnostics and environmental monitoring devices. By combining the adaptive behavior of microfluidic biofuel cells (micro-BFCs) self-regulating the power release with aptamer IMP logic, we constructed a novel IMP-Reset gate-based reusable and self-powered on-chip aptasensor, which can be used to logically determine the presence of one specific target in the absence of another target in complex physiological samples (such as human serum) in a single test.
Co-reporter:Yuanhong Xu, Xiurong Yang, Erkang Wang
Analytica Chimica Acta 2010 Volume 683(Issue 1) pp:12-20
Publication Date(Web):17 December 2010
DOI:10.1016/j.aca.2010.10.007
This review, covering reports published from 2002 to August 2010, shows how aptamers have made significant contributions in the improvements of microfluidic chips for affinity extraction, separations and detections. Furthermore, microfluidic chip methods for studying aptamer-target interactions and performing aptamer selections have also been summarized. Accordingly, research vacancies and future development trends in these areas are discussed.
Co-reporter:Xuan Yang, Tao Li, Bingling Li and Erkang Wang
Analyst 2010 vol. 135(Issue 1) pp:71-75
Publication Date(Web):10 Nov 2009
DOI:10.1039/B913036E
A novel visual method for K+ detection is developed utilizing a K+-sensitive G-quadruplex DNA named PS5.M as the sensing element. In the absence of K+, PS5.M is in a random coil state and does not bind hemin. Upon addition of K+, PS5.M folds into the quadruplex structure stabilized by K+. Such quadruplex structure is able to bind hemin to form the hemin-G-quadruplex DNAzyme that catalyzes the H2O2-mediated oxidation of colorless 3,3′,5,5′-tetramethylbenzidine to the blue product. Under the optimal conditions, the color change can be clearly observed with the naked eye in the concentration range from 2 to 1000 μM. Through this facile approach, K+ can be detected down to 2 μM, with high selectivity against other cations. In view of its simplicity, sensitivity and specificity, our developed visual method for K+ detection would potentially be utilized for bioassays and K+-sensitive test paper.
Co-reporter:Chaogui Chen, Jichao Zhang, Yan Du, Xiurong Yang and Erkang Wang
Analyst 2010 vol. 135(Issue 5) pp:1010-1014
Publication Date(Web):15 Feb 2010
DOI:10.1039/B924545F
In this paper, a new two-step photolithography fabrication method is used for the fabrication of an on-chip integrated two-metal electrode system, with a Ag reference electrode and two gold electrodes used as working and counter electrodes, respectively. Combined with a microfluidic channel, the total detector has the advantages of ease of use, low analyte consumption, fast sensing time and is suited for in situ target metal ion determination. Herein, the three-electrode system was used for Hg2+ ion measurement, and both the capabilities of Au working and Ag reference electrodes were characterized by using electrochemical techniques. The results show that the as-prepared on-chip integrated electrochemical detector performed with high sensitivity and good reproducibility in Hg2+ determination. The detection range extends from 10 to 1000 ppb with a good linear correlation, and the detection limit is low to 3 ppb (S/N = 3). Our method provides a rapid and effective, miniaturized electrochemical analysis platform in Hg2+ measurement and demonstrates great potential for the application of in situ or on-line mercuric pollutant analysis.
Co-reporter:Li-Jian HUANG, Er-Kang WANG
Chinese Journal of Analytical Chemistry 2010 Volume 38(Issue 2) pp:149-152
Publication Date(Web):February 2010
DOI:10.1016/S1872-2040(09)60020-7
Co-reporter:Yan Du, Chaogui Chen, Bingling Li, Ming Zhou, Erkang Wang, Shaojun Dong
Biosensors and Bioelectronics 2010 Volume 25(Issue 8) pp:1902-1907
Publication Date(Web):15 April 2010
DOI:10.1016/j.bios.2010.01.003
Herein, we report two simple label-free electrochemical aptasensors for protein detection using layer-by-layer (LBL) self-assembled multilayers with ferrocene-appended poly(ethyleneimine) (Fc-PEI), carbon nanotubes (CNTs) and aptamer. In one sensing strategy, the Fc-PEI, CNTs and DNA aptamer are LBL assembled on the electrode surface via electrostatic interaction. In the presence of target, the aptamer on the outermost layer of the LBL self-assembled multilayer would catch the target on the electrode interface, which makes a barrier for electrons and inhibits the electro-transfer, resulting in the decreased DPV signals of Fc-PEI. Using this strategy, a wide detection range (0.3–165 ng ml−1) for model target thrombin is obtained, with a low detection limit of 0.14 ng ml−1. In the similar sensing strategy for detection of lysozyme, a wide detection range (0.2 ng ml−1 to 1.66 μg ml−1) and a low detection limit (0.17 ng ml−1) are obtained. These results prove that the LBL sensing strategies developed possess sensitivity, selectivity, stability and generality.
Co-reporter:Libing Zhang, Hui Wei, Jing Li, Tao Li, Dan Li, Yunhui Li, Erkang Wang
Biosensors and Bioelectronics 2010 Volume 25(Issue 8) pp:1897-1901
Publication Date(Web):15 April 2010
DOI:10.1016/j.bios.2010.01.002
In this paper, a sensitive and selective fluorescent aptasensor for adenosine triphosphate (ATP) detection is constructed, based on the noncovalent assembly of dye-labeled ATP aptamer and single-walled carbon nanotubes (SWNTs). In the absence of ATP, the dye tethered to the ATP aptamer is close to SWNTs, which can effectively quench fluorescence of the dye. Upon adding ATP, the fluorophore keeps away from the quencher, since ATP specifically binds to the aptamer and competes with carbon nanotubes, resulting in an increase in the fluorescence intensity. This enables ATP to be detected down to 4.5 nM. To the best of our knowledge, this is the most sensitive fluorescent ATP aptasensor. In addition, prominent fluorescence signals were obtained in cellular ATP assays, thus the aptasensor could be used to detect ATP in real samples.
Co-reporter:Shaojun Guo, Dan Wen, Yueming Zhai, Shaojun Dong and Erkang Wang
ACS Nano 2010 Volume 4(Issue 7) pp:3959
Publication Date(Web):June 22, 2010
DOI:10.1021/nn100852h
The development of nanoscience and nanotechnology has inspired scientists to continuously explore new electrode materials for constructing an enhanced electrochemical platform for sensing. In this article, we proposed a new Pt nanoparticle (NP) ensemble-on-graphene hybrid nanosheet (PNEGHNs), a new electrode material, which was rapidly prepared through a one-step microwave-assisted heating procedure. The advantages of PNEGHNs modified glassy carbon electrode (GCE) (PNEGHNs/GCE) are illustrated from comparison with the graphenes (GNs) modified GCE for electrocatalytic and sensing applications. The electrocatalytic activities toward several organic and inorganic electroactive compounds at the PNEGHNs/GCE were investigated, all of which show a remarkable increase in electrochemical performance relative to GNs/GCE. Hydrogen peroxide (H2O2) and trinitrotoluene (TNT) were used as two representative analytes to demonstrate the sensing performance of PNEGHNs. It is found that PNEGHNs modified GCE shows a wide linear range and low detection limit for H2O2 and TNT detection. Therefore, PNEGHNs may be an attractive robust and advanced hybrid electrode material with great promise for electrochemical sensors and biosensors design.Keywords: electrocatalysis; graphene; hybrid nanomateirals; Pt nanoparticle; sensor
Co-reporter:Dan Wen, Shaojun Guo, Shaojun Dong, Erkang Wang
Biosensors and Bioelectronics 2010 Volume 26(Issue 3) pp:1056-1061
Publication Date(Web):15 November 2010
DOI:10.1016/j.bios.2010.08.054
Nanomaterial modified electrode is useful for catalytic, analytical and biotechnological applications. Herein, a simple and sensitive method for the electrocatalytic detection of ascorbic acid (AA) using ultrathin Pd nanowire (NW) modified glassy carbon electrode is presented. Electrochemical data reveal that Pd NWs can effectively enhance the electron transfer between AA and electrode, and thus reduce the overpotential of AA oxidation. Particularly, the current–time curve shows that the catalytic oxidation current is linearly dependent on AA concentration in the range of 25 μM–0.9 mM with a correlation coefficient 0.9998, and a detection limit of 0.2 μM (S/N = 3) is obtained with an excellent reproducibility. What is more, the present Pd NWs-based electrochemical sensing platform can successfully be used as enhanced element for the detection of AA in the practical samples such as human serum and vitamin C beverage with satisfactory results.
Co-reporter:Yan Du;Bingling Li
Bioanalytical Reviews 2010 Volume 1( Issue 2-4) pp:187-208
Publication Date(Web):2010 August
DOI:10.1007/s12566-010-0011-0
Gold nanoparticles (AuNPs) exhibit many predominant capabilities such as high biocompatibility, chemical stability, strong localized surface plasmon resonance absorption, and high extinction coefficient in the visible region. These properties have enabled the extensive use of AuNPs in optical and electrochemical biosensors. As a kind of functional nucleic acids, aptamers can be considered as a valid alternative to antibodies or other bio-receptors and have been widely employed to develop novel biosensors. We are summarizing here the state of the art of AuNP-based biosensors that use functional aptamers as molecular recognition elements. In many cases, AuNPs themselves can be used as a probe for detection, such as various colorimetric aptasensors and fluorescent aptasensors. They also can be used as probe vectors to enlarge detection signals and to increase the number of conceivable substrates in electrochemical aptasensors.
Co-reporter:Shaojun Guo ; Jing Li ; Shaojun Dong
The Journal of Physical Chemistry C 2010 Volume 114(Issue 36) pp:15337-15342
Publication Date(Web):August 24, 2010
DOI:10.1021/jp104942d
Pt-based bimetallic dendritic nanoparticles (NPs) with noncompact nanobranches show great potential as catalysts for reducing Pt consumption, providing a high surface area and facilitating the enhanced performance in the catalytic applications. However, developing a one-step route to synthesize such dendritic NPs with a well-defined morphology at room temperature is still a great challenge and has been rarely reported. Herein, we report a one-step, room-temperature, and aqueous route for the synthesis of Pt-on-Au bimetallic dendritic NPs with noncompact nanobranches (denoted as BDNNNs) in high yield (∼100%). These BDNNNs have many big gaps available among the Pt nanobranches, which are important for providing a high electrochemical surface area. Methanol was selected as a model molecule for studying the electrocatalytic performance of BDNNNs. Interestingly, it is found that BDNNNs have a higher electrochemically active area than Au@Pt core/shell NPs with a rough surface and thus lead to higher catalytic activity for methanol oxidation. Moreover, for BDNNNs, the surface plasmonic resonance (SPR) peak of the Au core can be observed even when many Pt nanobranches are supported on the Au core because of the noncompact Pt nanobranches, which is important for in situ spectroscopic (such as surface-enhanced Raman scattering) characterization of catalytic reactions.
Co-reporter:Zuojia Liu, Jin Wang and Erkang Wang
The Journal of Physical Chemistry B 2010 Volume 114(Issue 1) pp:638-642
Publication Date(Web):December 10, 2009
DOI:10.1021/jp909017j
The molecular analysis of thymopentin (TP5)/class II major histocompatibility complex (MHC II) complexes has been basically understood; however, the mechanism by which TP5-MHC II complexes are formed is largely unexplored. Compared with Epstein−Barr virus (EBV)-transformed B cells expressing human leucocyte antigen DR (HLA-DR), no fluorescent signal was observed on the DR-deficient cell line. This indicates that FITC labeled TP5 (FITC-TP5) is genuinely bound to HLA-DR. The binding specificity was confirmed by incubating FITC-TP5 with unlabeled TP5 and HA peptide as well as mAb for DR molecules. In addition, the binding appeared to be rapid in living antigen-presenting cell (APC), which implies that TP5 is demonstrated on APC surface and does not require processing before associating with DR. Additional support for this surface binding arises from the observation that pretreatment of cells with a variety of metabolic inhibitors failed to decrease the level of TP5/DR complexes. However, temperature has an effect on the rate of binding between TP5 and DR molecules, which is well consistent with the qualitative predication of transition state theory. The formation of antigenic complexes is accelerated at acidic pH, which shows that the formation of TP5/DR complexes is a pH-dependent process.
Co-reporter:Yujing Guo, Shaojun Guo, Jiangtao Ren, Yueming Zhai, Shaojun Dong and Erkang Wang
ACS Nano 2010 Volume 4(Issue 7) pp:4001
Publication Date(Web):June 28, 2010
DOI:10.1021/nn100939n
Cyclodextrins (CDs) are oligosaccharides composed of six, seven, or eight glucose units (α-, β-, or γ-CD, respectively), which are toroidal in shape with a hydrophobic inner cavity and a hydrophilic exterior. These interesting characteristics can enable them to bind selectively various organic, inorganic and biological guest molecules into their cavities to form stable host−guest inclusion complexes or nanostructured supramolecular assemblies in their hydrophobic cavity. On the other hand graphene nanosheet (GN), a rising-star material, holds great promise for potential applications in many technological fields due to its high surface areas, low cost, and high conductivity. If GNs are modified with CDs, it is possible to obtain new materials simultaneously possessing unique properties of GNs and cyclodextrins through combining their individual obvious advantages. In this article, we demonstrate for the first time a simple wet-chemical strategy for the preparation of CD−graphene organic−inorganic hybrid nanosheets (CD−GNs), which exhibited high solubility and stability in polar solvent. The obtained CD−GNs were characterized by UV−vis spectroscopy, static contact angle measurement, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, atomic force microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy, which confirmed that CD had been effectively functionalized on the surface of GNs. Furthermore, the formation mechanism of CD−GNs was also discussed. Interestingly, GNs here could load a number of CD molecules, which was very important for greatly enhancing the supramolecular function of CDs. Electrochemical results obviously reveal that CD−graphene organic−inorganic hybrid nanosheets could exhibit very high supramolecular recognition and enrichment capability and show much higher electrochemical response toward eight probe molecules (biomolecules and drugs) than unmodified GNs and carbon nanotubes, which is probably caused by the synergetic effects from GNs (high conductivity and high surface area) and CD molecules (host−guest recognition and enrichment).Keywords: cyclodextrin; electrocatalysis; electrochemical device; graphene; supramolecular
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
ACS Nano 2010 Volume 4(Issue 1) pp:547
Publication Date(Web):December 15, 2009
DOI:10.1021/nn9014483
Graphene nanosheet, the hottest material in physics and materials science, has been studied extensively because of its unique electronic, thermal, mechanical, and chemical properties arising from its strictly 2D structure and because of its potential technical applications. Particularly, these remarkable characteristics enable it to be a promising candidate as a new 2D support to load metal nanoparticles (NPs) for application in fuel cells. However, constructing high-quality graphene/bimetallic NP hybrids with high electrochemical surface area (ECSA) remains a great challenge to date. In this paper, we demonstrate for the first time a wet-chemical approach for the synthesis of high-quality three-dimensional (3D) Pt-on-Pd bimetallic nanodendrites supported on graphene nanosheets (TP-BNGN), which represents a new type of graphene/metal heterostructure. The resulting hybrids were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Raman spectroscopy, and electrochemical technique. It is found that small single-crystal Pt nanobranches supported on Pd NCs with porous structure and good dispersion were directly grown onto the surface of graphene nanosheets, which exhibits high electrochemical active area. Furthermore, the number of nanobranches for Pt-on-Pd bimetallic nanodendrites on the surface of graphene nanosheets could be easily controlled via simply changing the synthetic parameters, thus resulting in the tunable catalytic properties. Most importantly, the electrochemical data indicate that the as-prepared graphene/bimetallic nanodendrite hybrids exhibited much higher electrocatalytic activity toward methanol oxidation reaction than the platinum black (PB) and commercial E-TEK Pt/C catalysts.Keywords: bimetallic nanostructure; fuel cell; graphene nanosheet; nanodendrite; nanoelectrocatalyst
Co-reporter:Youxing Fang;Shaojun Guo;Chengzhou Zhu;Shaojun Dong
Chemistry – An Asian Journal 2010 Volume 5( Issue 8) pp:1838-1845
Publication Date(Web):
DOI:10.1002/asia.201000004
Abstract
Herein we report a facile and efficient method for self-assembling noble-metal nanoparticles (NPs) to the surface of SnO2-coated carbon nanotubes (CNT@SnO2) to construct CNT@SnO2/noble metal NP hybrids. By using SnCl4 as the precursor of the SnO2 shell on the surface of CNTs, the hydrolysis speed of SnCl4 was slowed down in ethanol containing a trace amount of urea and water. The coaxial nanostructure of CNT@SnO2 was confirmed by using X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). It was found that the coating layer of SnO2 was homogeneous with the mean thickness of 8 nm. The CNT@SnO2/noble-metal NP hybrids were obtained by mixing noble-metal NPs with as-prepared CNT@SnO2 coaxial nanocables by means of a self-assembly strategy. With the amino group terminated, the CNT@SnO2 coaxial nanocable can readily adsorb the as-prepared noble-metal NPs (Au, Ag, AuPt, and AuPd NPs). The presence of an amino group at the surface of SnO2 was proved by use of X-ray photoelectron spectroscopy (XPS). In addition, H2O2 sensing by amperometric methods could serve as detection models for investigating the electrocatalytic ability of as-prepared hybrid materials. It was found that wide linear ranges and low detection limits were obtained by using the enzyme-free CNT@SnO2@AuPt modified electrode, which indicated the potential utilizations of the hybrid based on CNT@SnO2 for electrochemical sensing.
Co-reporter:Youxing Fang, Shaojun Guo, Chengzhou Zhu, Yueming Zhai and Erkang Wang
Langmuir 2010 Volume 26(Issue 13) pp:11277-11282
Publication Date(Web):March 16, 2010
DOI:10.1021/la100575g
We demonstrate the use of cationic polyelectrolyte poly(diallyldimethyl ammonium chloride) (PDDA) functionalized graphene nanosheets (GNs) as the building block in the self-assembly of GNs/Au nanoparticles (NPs) heterostructure to enhance the electrochemical catalytic ability. To ensure the GNs were modified with PDDA successfully, we study the PDDA/GNs with atomic force microscopy (AFM) and zeta potential measurements on the roughness and zeta potential changes relative to those of unmodified GNs, respectively. Then, the citrate-capped Au NPs are employed as the other model particles to construct two-dimensional GNs/NPs heterostructure. Here, the use of PDDA modifiers not only alters the electrostatic charges of graphene, but also probably provides a convenient self-assembly approach to the hybridization of graphene. Furthermore, we employ the high-loading Au NPs on graphene (GN/Au-NPs) as the electrochemical enhanced material for H2O2 sensing (as the model analyte). The wide linear ranges and low detection limits are obtained using the chronoamperometry technique at the GN/Au-NPs-modified glassy carbon electrode.
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
The Journal of Physical Chemistry C 2010 Volume 114(Issue 11) pp:4797-4802
Publication Date(Web):February 25, 2010
DOI:10.1021/jp909623x
We have developed a facile procedure to synthesize semiconductor/metal Te/Pt hybrid nanowire (NW) with nanoporous surface through the Te/Pt contact without prior Te NWs functionalization, which represents a new type of semiconductor/metal heterostructure. Specifically, the growth of Pt nanoparticles (NPs) on the surface of Te NWs could be performed at room temperature, without the need for templates and surfactants. The resulting Te/Pt hybrid NWs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV−visible spectra, energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. It is found that ultrahigh density small Pt NPs of about 3 nm directly adhere to Te NWs and further form a morphology with nanoporous structures, which exhibit an enlarged electroactive surface area relative to that of commercial platinum black (CPB) catalyst. Most importantly, the as-prepared Te/Pt hybrid NWs exhibit high electrocatalytic activity toward the methanol oxidation reaction (MOR), indicating that they have potential for fuel-cell applications.
Co-reporter:Bingling Li Dr.;Shaojun Dong
Chemistry – An Asian Journal 2010 Volume 5( Issue 6) pp:1262-1272
Publication Date(Web):
DOI:10.1002/asia.200900660
Abstract
In this Focus Review, we introduce a kind of “label-free” and “substrate-free” (LFSF) aptasensor that carries out the whole sensing process in a homogeneous solution. This means that commonly used covalent label; separation, and immobilization steps in biosensors are successfully avoided, which simplifies the sensing operations to the greatest degree. After brief description about the advantages of aptamers and “LFSF” aptasensors, the main content of the review is divided into fluorescent aptasenors, calorimetric aptasensors, and hemin-aptamer-DNAzyme “LFSF” aptasensors, which are three most widely developed sensing systems in this field. It is hoped that this review can provide an overall scene about how aptamers function as ideal recognition elements in smart analysis.
Co-reporter:Youxing Fang, Shaojun Guo, Chengzhou Zhu, Shaojun Dong, and Erkang Wang
Langmuir 2010 Volume 26(Issue 23) pp:17816-17820
Publication Date(Web):October 28, 2010
DOI:10.1021/la1036597
A rapid, templateless, surfactantless, electrochemical route is reported to synthesize uniform and clean Pd nanoparticles (∼350 nm in diameter) with a substructure of sharp nanospikes (∼95 nm in length). The effects of electrodeposition potential, PdCl2 concentration, and supporting electrolyte were explored for the formation of the Pd nanourchins. The systematic studies revealed that the concentration of Pd(II) greatly affects the density of the nanospikes on the Pd nanourchins in this short-time synthesis. The substructure of the nanospikes on the nanourchins was examined to be a single-crystal quadrangular pyramid. Further investigation of the Pd nanourchins by cyclic voltammetry (CV) showed their high electrochemical activity toward formic acid oxidation.
Co-reporter:Dan Li, Gaiping Li, Peicai Li, Lixue Zhang, Zuojia Liu, Jin Wang, Erkang Wang
Biomaterials 2010 31(7) pp: 1850-1857
Publication Date(Web):
DOI:10.1016/j.biomaterials.2009.11.027
Co-reporter:Weiwei Guo ; Jipei Yuan ; Qingzhe Dong
Journal of the American Chemical Society 2009 Volume 132(Issue 3) pp:932-934
Publication Date(Web):December 28, 2009
DOI:10.1021/ja907075s
Fluorescent silver nanoclusters were successfully synthesized using hybridized DNA duplexes as capping scaffolds. The formation of these emitters was highly sequence-dependent and could specifically identify a single nucleotide mutation, the sickle cell anemia gene mutation. Furthermore, the identification of single-nucleotide differences using this strategy was extended to more general types of single-nucleotide mismatches.
Co-reporter:Tao Li ; Erkang Wang ;Shaojun Dong
Journal of the American Chemical Society 2009 Volume 131(Issue 42) pp:15082-15083
Publication Date(Web):October 6, 2009
DOI:10.1021/ja9051075
A cation-driven allosteric G-quadruplex DNAzyme (PW17) was utilized to devise a conceptually new class of DNA logic gate based on cation-tuned ligand binding and release. K+ favors the binding of hemin to parallel-stranded PW17, thereby promoting the DNAzyme activity, whereas Pb2+ induces PW17 to undergo a parallel-to-antiparallel conformation transition and thus drives hemin to release from the G-quadruplex, deactivating the DNAzyme. Such a K+−Pb2+ switched G-quadruplex, in fact, functions as a two-input INHIBIT logic gate. With the introduction of another input EDTA, this G-quadruplex can be further utilized to construct a reversibly operated IMPLICATION gate.
Co-reporter:Shaojun Guo, Jing Li, Wen Ren, Dan Wen, Shaojun Dong and Erkang Wang
Chemistry of Materials 2009 Volume 21(Issue 11) pp:2247
Publication Date(Web):April 29, 2009
DOI:10.1021/cm900300v
In this paper, we have reported a very simple strategy (combined sonication with sol−gel techniques) for synthesizing well-defined silica-coated carbon nanotube (CNT) coaxial nanocable without prior CNT functionalization. After functionalization with NH2 group, the CNT/silica coaxial nanocable has been employed as a three-dimensional support for loading ultra-high-density metal or hybrid nanoparticles (NPs) such as gold NPs, Au/Pt hybrid NPs, Pt hollow NPs, and Au/Ag core/shell NPs. Most importantly, it is found that the ultra-high-density Au/Pt NPs supported on coaxial nanocables (UASCN) could be used as enhanced materials for constructing electrochemical devices with high performance. Four model probe molecules (O2, CH3OH, H2O2, and NH2NH2) have been investigated on UASCN-modified glassy carbon electrode (GCE). It was observed that the present UASCN exhibited high electrocatalytic activity toward diverse molecules and was a promising electrocatalyst for constructing electrochemical devices with high performance. For instance, the detection limit for H2O2 with a signal-to-noise ratio of 3 was found to be 0.3 μM, which was lower than certain enzyme-based biosensors. And the detection limit for hydrazine is <0.5 μM, which was lower than amperometric hydrazine sensors based on functional nanomaterials such as zinc oxide nanonails, CNTs-modified electrodes, o-aminophenol grafted GCE electrode, and multilayer film containing cobalt phthalocyanine. Furthermore, the as-obtained high-density gold/silver core/shell NPs supported on coaxial nanocables could be used as a good surface-enhanced Raman scattering (SERS) substrate for the detection of different molecules [4-aminothiophenol (4-ATP) and adenine], showing the great potential of CNT/SiO2/(Au/Ag) as a convenient and powerful SERS substrate for biological tags and biological molecular detection.
Co-reporter:Weiwei Guo, Jipei Yuan and Erkang Wang
Chemical Communications 2009 (Issue 23) pp:3395-3397
Publication Date(Web):27 Apr 2009
DOI:10.1039/B821518A
Fluorescent oligonucleotide-stabilized Ag nanoclusters are demonstrated as novel and environmentally-friendly fluorescence probes for the determination of Hg2+ ions with a low detection limit and high selectivity.
Co-reporter:Tao Li, Bingling Li, Erkang Wang and Shaojun Dong
Chemical Communications 2009 (Issue 24) pp:3551-3553
Publication Date(Web):07 May 2009
DOI:10.1039/B903993G
Hg2+ is able to inhibit the peroxidase-like DNAzyme function of a T-containing G-quadruplex DNAviaHg2+-mediated T–T base pairs, which enables the visual detection of Hg2+ in the TMB–H2O2 reaction system with high selectivity and sensitivity.
Co-reporter:Bingyan Han, Jipei Yuan and Erkang Wang
Analytical Chemistry 2009 Volume 81(Issue 13) pp:5569
Publication Date(Web):June 5, 2009
DOI:10.1021/ac900769h
Herein, a sensitive and selective sensor for biothiols based on the recovered fluorescence of the CdTe quantum dots (QDs)−Hg(II) system is reported. Fluorescence of QDs could be quenched greatly by Hg(II). In the presence of biothiols, such as glutathione (GSH), homocysteine (Hcy), and cysteine (Cys), however, Hg(II) preferred to react with them to form the Hg(II)−S bond because of the strong affinity with the thiols of biothiols rather than quenching the fluorescence of the QDs. Thus, the fluorescence of CdTe QDs was recovered. The restoration ability followed the order GSH > Hcy > Cys due to the decreased steric hindrance effect. A good linear relationship was obtained from 0.6 to 20.0 μmol L−1 for GSH and from 2.0 to 20.0 μmol L−1 for Cys, respectively. The detection limits of GSH and Cys were 0.1 and 0.6 μmol L−1, respectively. In addition, the method showed a high selectivity for Cys among the other 19 amino acids. Furthermore, it succeeded in detecting biothiols in the Hela cell.
Co-reporter:Tao Li, Shaojun Dong and Erkang Wang
Analytical Chemistry 2009 Volume 81(Issue 6) pp:2144
Publication Date(Web):February 19, 2009
DOI:10.1021/ac900188y
Mercury ion (Hg2+) is able to specifically bind to the thymine−thymine (T−T) base pair in a DNA duplex, thus providing a rationale for DNA-based selective detection of Hg2+ with various means. In this work, we for the first time utilize the Hg2+-mediated T−T base pair to modulate the proper folding of G-quadruplex DNAs and inhibit the DNAzyme activity, thereby pioneering a facile approach to sense Hg2+ with colorimetry. Two bimolecular DNA G-quadruplexes containing many T residues are adopted here, which function well in low- and high-salt conditions, respectively. These G-quadruplex DNAs are able to bind hemin to form the peroxidase-like DNAzymes in the folded state. Upon addition of Hg2+, the proper folding of G-quadruplex DNAs is inhibited due to the formation of T−Hg2+−T complex. This is reflected by the notable change of the Soret band of hemin when investigated by using UV−vis absorption spectroscopy. As a result of Hg2+ inhibition, a sharp decrease in the catalytic activity toward the H2O2-mediated oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is observed, accompanied by a change in solution color. Through this approach, aqueous Hg2+ can be detected at 50 nM (10 ppb) with colorimetry in a facile way, with high selectivity against other metal ions. These results indicate our introduced label-free method for colorimetric Hg2+ detection is simple, quantitative, sensitive, and highly selective.
Co-reporter:Jipei Yuan, Weiwei Guo, Xiurong Yang and Erkang Wang
Analytical Chemistry 2009 Volume 81(Issue 1) pp:362
Publication Date(Web):November 24, 2008
DOI:10.1021/ac801533u
A sensing system based on the photoinduced electron transfer of quantum dots (QDs) was designed to measure the interaction of anticancer drug and DNA, taking mitoxantrone (MTX) as a model drug. MTX adsorbed on the surface of QDs can quench the photoluminescence (PL) of QDs through the photoinduced electron-transfer process; and then the addition of DNA will bring the restoration of QDs PL intensity, as DNA can bind with MTX and remove it from QDs. Sensitive detection of MTX with the detection limit of 10 nmol L−1 and a linear detection range from 10 nmol L−1 to 4.5 μmol L−1 was achieved. The dependence of PL intensity on DNA amount was successfully utilized to investigate the interactions between MTX and DNA. Both the binding constants and the sizes of binding site of MTX−DNA interactions were calculated based on the equations deduced for the PL recovery process. The binding constant obtained in our experiment was generally consistent with previous reports. The sensitive and speedy detection of MTX as well as the avoidance of modification or immobilization process made this system suitable and promising in the drug−DNA interaction studies.
Co-reporter:Jing Li, Shaojun Guo, Yueming Zhai, Erkang Wang
Analytica Chimica Acta 2009 Volume 649(Issue 2) pp:196-201
Publication Date(Web):7 September 2009
DOI:10.1016/j.aca.2009.07.030
Graphene nanosheets, dispersed in Nafion (Nafion-G) solution, were used in combination with in situ plated bismuth film electrode for fabricating the enhanced electrochemical sensing platform to determine the lead (Pb2+) and cadmium (Cd2+) by differential pulse anodic stripping voltammetry (DPASV). The electrochemical properties of the composite film modified glassy carbon electrode were investigated. It is found that the prepared Nafion-G composite film not only exhibited improved sensitivity for the metal ion detections, but also alleviated the interferences due to the synergistic effect of graphene nanosheets and Nafion. The linear calibration curves ranged from 0.5 μg L−1 to 50 μg L−1 for Pb2+ and 1.5 μg L−1 to 30 μg L−1 for Cd2+, respectively. The detection limits (S/N = 3) were estimated to be around 0.02 μg L−1 for Pb2+ and Cd2+. The practical application of the proposed method was verified in the water sample determination.
Co-reporter:Lixue Zhang, Liang Wang, Shaojun Guo, Junfeng Zhai, Shaojun Dong, Erkang Wang
Electrochemistry Communications 2009 Volume 11(Issue 2) pp:258-261
Publication Date(Web):February 2009
DOI:10.1016/j.elecom.2008.11.020
Monodisperse, submicrometer-scale platinum (Pt) colloidal spheres were prepared through a simple direct chemical reduction of p-phenylenediamine (PPD)-chloroplatinic acid (H2PtCl6) coordination polymer colloids. It was found that the prepared Pt colloids had the similar size and morphology with their coordination polymer precursors, and the prepared Pt colloids with rough surfaces were three-dimensional (3D) structured assemblies of high-density small Pt nanoparticles. The electrochemical experiments confirmed that the prepared Pt colloids possessed a high electrocatalytic activity towards mainly four-electron reduction of dioxygen to water, making the prepared Pt colloids potential candidates for the efficient cathode material in fuel cells.
Co-reporter:Jing Li, Shaojum Guo, Yueming Zhai, Erkang Wang
Electrochemistry Communications 2009 Volume 11(Issue 5) pp:1085-1088
Publication Date(Web):May 2009
DOI:10.1016/j.elecom.2009.03.025
In this work, an ultrasensitive platform for the detection of cadmium (Cd2+) combining the nafion–graphene nanocomposite film with differential pulse anodic stripping voltammetry (DPASV) analysis was presented. It is found that this sensing platform exhibits enhanced response to the determination of the Cd2+ and has been used to determine the Cd2+ in real sample with good recovery.
Co-reporter:Yuanhong Xu, Erkang Wang
Journal of Chromatography A 2009 Volume 1216(Issue 24) pp:4817-4823
Publication Date(Web):12 June 2009
DOI:10.1016/j.chroma.2009.04.024
This review, covering reports published from 2001 to December 2008, shows how ionic liquids (ILs) have made significant contributions in the improvement of capillary and microchip electrophoresis (CE and μCE) for the separation and detection of analytes such as phenols and aromatic acids, metal ions, medicines, enantiomers, biological materials, etc. Furthermore, CE methods applied in the sensitive and accurate determination of physico-chemical properties of ILs have been summarized. Accordingly, research vacancies and future development trends in these areas are discussed.
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
Crystal Growth & Design 2009 Volume 9(Issue 1) pp:372
Publication Date(Web):November 26, 2008
DOI:10.1021/cg800583h
In this paper, we for the first time report a polyol method for large-scale synthesis of rectangular silver nanorods in the presence of directing agent and seeds. This method has some clear advantages including simplicity, high quality, and ease of scaleup. Silver nanowires or silver nanorods with a submicrometer diameter could also be facilely prepared when the reaction parameters are slightly changed. Furthermore, a liquid−liquid assembly strategy has been employed to construct uniform rectangular silver nanorod arrays on a solid substrate which could be used as surface-enhanced Raman scattering (SERS) substrates with high SERS activity, stability, and reproducibility. It is found that the SERS spectra obtained from the probe molecules with the different concentrations show different SERS intensities. As the concentration of 4-aminothiophenol (4-ATP) or rhodamine 6G (R6G) increases, the SERS intensities progressively increase. The enhancement factor for 4-ATP and R6G should be as large as 5.06 × 104 or much larger than the value of 5.06 × 108, respectively. Most importantly, the SERS spectra of R6G on the assembling film are well reproducible at different sites on a substrate, with a standard deviation of <20%. Our results will open new possibilities for applying SERS to detect different analytical species due to the good reproducibility of the present SERS substrate.
Co-reporter:Zhaozi Lv, Hui Wei, Bingling Li and Erkang Wang
Analyst 2009 vol. 134(Issue 8) pp:1647-1651
Publication Date(Web):22 Jun 2009
DOI:10.1039/B909069J
Among the functional nucleic acids studied, adenine-rich nucleic acids have attracted attention due to their critical roles in many biological processes and self-assembly-based nanomaterials, especially deoxyribonucleic acids (abbreviated as poly(dA)). Therefore the ligands binding to poly(dA) might serve as potential therapeutic agents. Coralyne, a kind of planar alkaloid, has been firstly found that it could bind strongly to poly(dA). This work herein reports an approach for visual sensing of the coralyne–poly(dA) interaction. This method was based on the coralyne inducing poly(dA) into the homo-adenine DNA duplex and the difference in electrostatic affinity between single-stranded DNA and double-stranded DNA with gold nanoparticles (GNPs). Furthermore, we applied the recognition process of the interaction between coralyne and poly(dA) into specific coralyne detection with the assistance of certain software (such as Photoshop). A linear response from 0 to 728 nM was obtained for coralyne, and a detection limit of 91 nM was achieved.
Co-reporter:Jing Li, Jichao Zhang, Hui Wei and Erkang Wang
Analyst 2009 vol. 134(Issue 2) pp:273-277
Publication Date(Web):24 Oct 2008
DOI:10.1039/B804670K
This work herein reports the approach for the simultaneous determination of heavy metal ions including cadmium (Cd(II)), lead (Pb(II)), and chromium (Cr(VI)) using a bismuth film electrode (BFE) by anodic stripping voltammertry (ASV). The BFE used was plated in situ. Due to the reduction of Cr(VI) with H2O2 in the acid medium, on one hand, the Cr(III) was produced and Cr(VI) was indirectly detected by monitoring the content of Cr(III) using square-wave ASV. On the other hand, Pb(II) was also released from the complex between Pb(II) and Cr(VI). Furthermore, the coexistence of the Cd(II) was also simultaneously detected with Pb(II) and Cr(VI) in this system as a result of the formation of an alloy with Bi. The detection limits of this method were 1.39 ppb for Cd(II), 2.47 ppb for Pb(II) and 5.27 ppb for Cr(VI) with a preconcentration time of 120 s under optimal conditions (S/N = 3), respectively. Furthermore, the sensitivity of this method can be improved by controlling the deposition time or by using a cation-exchange polymer (such as Nafion) modified electrode.
Co-reporter:Gaiping Li;Dan Li;Lixue Zhang;Junfeng Zhai Dr.
Chemistry - A European Journal 2009 Volume 15( Issue 38) pp:9868-9873
Publication Date(Web):
DOI:10.1002/chem.200900914
Abstract
We report here a facile method to obtain folic acid (FA)-protected gold nanoparticles (Au NPs) by heating an aqueous solution of HAuCl4/FA in which FA acts as both the reducing and stabilizing agent. The successful formation of FA-protected Au NPs is demonstrated by UV/Vis spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The intracellular uptake of these nanoparticles is facilitated by HeLa cells overexpressing the folate reporter, which itself is significantly inhibited by free FA in a competitive assay as quantified by inductively coupled plasma mass spectroscopy (ICP-MS). This simple one-step approach affords a new perspective for creating functional nanomaterials, and the resulting biocompatible, functional Au NPs may find some prospective applications in various biomedical fields.
Co-reporter:Shaojun Guo;Shaojun Dong
Chemistry - A European Journal 2009 Volume 15( Issue 10) pp:2416-2424
Publication Date(Web):
DOI:10.1002/chem.200801942
Co-reporter:Tao Li;Shaojun Dong Dr.
Chemistry – An Asian Journal 2009 Volume 4( Issue 6) pp:918-922
Publication Date(Web):
DOI:10.1002/asia.200900019
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 14) pp:5485-5492
Publication Date(Web):2017-2-22
DOI:10.1021/jp900493c
In this contribution, we for the first time report the synthesis of raspberry-like hierarchical Au/Pt nanoparticle (NP) assembling hollow spheres (RHAHS) with pore structure and complex morphology through one in situ sacrificial template approach without any post-treatment procedure. This method has some clear advantages including simplicity, quickness, high quality, good reproducibility, and no need of a complex post-treatment process (removing templating). Furthermore, the present method could be extended to other metal-based NP assembling hollow spheres. Most importantly, the as-prepared RHAHS exhibited excellent electrocatalytic activity for oxygen reduction reaction (ORR). For instance, the present RHAHS-modified electrode exhibited more positive potential (the half-wave potential at about 0.6 V), higher specific activity, and higher mass activity for ORR than that of commercial platinum black (CPB). Rotating ring-disk electrode (RRDE) voltammetry demonstrated that the RHAHS-modified electrode could almost catalyze a four-electron reduction of O2 to H2O in a 0.5 M air-saturated H2SO4 solution. The present RHAHS may hold great promise as an advanced material for applications in fuel cells, biosensors and electrochemical devices.
Co-reporter:Jin Wang;Chunhe Li;Xidi Wang
PNAS 2009 Volume 106 (Issue 10 ) pp:3752-3757
Publication Date(Web):2009-03-10
DOI:10.1073/pnas.0806427106
Identifying protein–protein interactions is crucial for understanding cellular functions. Genomic data provides opportunities
and challenges in identifying these interactions. We uncover the rules for predicting protein–protein interactions using a
frequent pattern tree (FPT) approach modified to generate a minimum set of rules (mFPT), with rule attributes constructed
from the interaction features of the yeast genomic data. The mFPT prediction accuracy is benchmarked against other commonly
used methods such as Bayesian networks and logistic regressions under various statistical measures. Our study indicates that
mFPT outranks other methods in predicting the protein–protein interactions for the database used. We predict a new protein–protein
interaction complex whose biological function is related to premRNA splicing and new protein–protein interactions within existing
complexes based on the rules generated. Our method is general and can be used to discover the underlying rules for protein–protein
interactions, genomic interactions, structure-function relationships, and other fields of research.
Co-reporter:Jipei Yuan, Weiwei Guo, Jianyuan Yin, Erkang Wang
Talanta 2009 Volume 77(Issue 5) pp:1858-1863
Publication Date(Web):15 March 2009
DOI:10.1016/j.talanta.2008.10.032
A simple and sensitive assay system for glucose based on the glutathione (GSH)-capped CdTe quantum dots (QDs) was developed. GSH-capped CdTe QDs exhibit higher sensitivity to H2O2 produced from the glucose oxidase catalyzed oxidation of glucose, and are also more biocompatible than other thiols-capped QDs. Based on the quenching of H2O2 on GSH-capped QDs, glucose can be detected. The detection conditions containing reaction time, the concentration of glucose oxidase and the sizes of QDs were optimized and the detection limits for glucose was determined to be 0.1 μM; two detection ranges of glucose from 1.0 μM to 0.5 mM and from 1.0 mM to 20 mM, respectively were obtained. The detection limit was almost a 1000 times lower than other QDs-based optical glucose sensing systems. The developed glucose detection system was simple and facile with no need of complicated enzyme immobilization and modification of QDs.
Co-reporter:Libing Zhang, Jing Li, Yuanhong Xu, Yueming Zhai, Yunhui Li, Erkang Wang
Talanta 2009 Volume 79(Issue 2) pp:454-459
Publication Date(Web):15 July 2009
DOI:10.1016/j.talanta.2009.04.009
An effective electrochemiluminescence (ECL) sensor based on Nafion/poly(sodium 4-styrene sulfonate) (PSS) composite film-modified ITO electrode was developed. The Nafion/PSS/Ru composite film was characterized by atomic force microscopy, UV–vis absorbance spectroscopy and electrochemical experiments. The Nafion/PSS composite film could effectively immobilize tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) via ion-exchange and electrostatic interaction. The ECL behavior of Ru(bpy)32+ immobilized in Nafion/PSS composite film was investigated using tripropylamine (TPA) as an analyte. The detection limit (S/N = 3) for TPA at the Nafion/PSS/Ru composite-modified electrode was estimated to be 3.0 nM, which is 3 orders of magnitude lower than that obtained at the Nafion/Ru modified electrode. The Nafion/PSS/Ru composite film-modified indium tin oxide (ITO) electrode also exhibited good ECL stability. In addition, this kind of immobilization approach was simple, effective, and timesaving.
Co-reporter:Bingyan Han, Yuanhong Xu, Lixue Zhang, Xiurong Yang, Erkang Wang
Talanta 2009 Volume 79(Issue 3) pp:959-962
Publication Date(Web):15 August 2009
DOI:10.1016/j.talanta.2009.04.030
This paper described a double-chained cationic surfactant, didodecyldimethylammonium bromide (DDAB), for dynamic surface modification of poly(dimethylsiloxane) (PDMS) microchips to reduce the fluorescent dyes adsorption onto the microchannel. When DDAB with a high concentration was present as the dynamic modification reagent in the running and sample buffer, it not only reversed the direction of electroosmotic flow, but also efficiently suppressed fluorescent dyes pyronine Y (PY) or rhodamine B (RB) adsorption onto the chip surface. In addition, vesicles formed by DDAB in the buffer with higher surface charge density and electrophoretic mobility could provide wider migration window and potential for the separation of compounds with similar hydrophobicity. Factors affecting modification, such as pH and concentrations of the buffer, DDAB concentration in the buffer were investigated. Compared with commonly used single-chained cetyltrimethylammonium bromide, DDAB provided a better modification performance. Furthermore, PY and RB were separated successfully on a PDMS microchip at the appropriate conditions with DDAB.
Co-reporter:Peicai Li, Lixue Zhang, Kelong Ai, Dan Li, Xiaohua Liu, Erkang Wang
Journal of Controlled Release 2008 Volume 129(Issue 2) pp:128-134
Publication Date(Web):14 July 2008
DOI:10.1016/j.jconrel.2008.04.006
The stability of the complex of cationic lipid with nucleic acid, especially when facing serum, is crucial for the efficiency of gene delivery. Here, we demonstrated that the stability of the complex of didodecyldimethylammonium bromide (DDAB, a cationic lipid) with DNA in the presence of serum dramatically increased after coating DDAB onto the surface of the gold nanoparticles. The stability of the complex was demonstrated with dye intercalation assay, and agarose gel electrophoresis. The process of the interaction was characterized with UV–vis spectra and the morphology of the complex was observed with atomic force microscope (AFM). Cell viability assays demonstrated that the cytotoxicity of DDAB was also decreased.
Co-reporter:Hui Wei, Chaogui Chen, Bingyan Han and Erkang Wang
Analytical Chemistry 2008 Volume 80(Issue 18) pp:7051
Publication Date(Web):July 29, 2008
DOI:10.1021/ac801144t
Colorimetric assay based on the unique surface plasmon resonance properties of metallic nanoparticles has received considerable attention in bioassay due to its simplicity, high sensitivity, and low cost. Most of colorimetric methods previously reported employed gold nanoparticles (GNPs) as sensing elements. In this work, we develop a sensitive, selective, simple, and label-free colorimetric assay using unmodified silver nanoparticle (AgNP) probes to detect enzymatic reactions. Enzymatic reactions concerning adenosine triphosphate (ATP) dephosphorylation by calf intestine alkaline phosphatase (CIAP) and peptide phosphorylation by protein kinase A (PKA) were studied. In the absence of the enzymes, unreacted ATP could protect AgNPs from salt-induced aggregation, whereas in the presence of the enzymes, the reaction product of ATP (i.e., adenosine for CIAP and ADP for PKA) could not. Via our method, dephosphorylation and phosphorylation could be readily detected by the color change of AgNPs, with a detection limit of 1 unit/mL for CIAP and a detection limit of 0.022 unit/mL for PKA. More importantly, the enzymatic inhibition by inhibitors and enzymatic activity in complex biological fluids could also be realized. This work is an important step toward a colorimetric assay using AgNPs and might provide a promise for enzyme assay in realistically complex systems and for screening of different enzyme inhibitors in future.
Co-reporter:Hui Wei, Jianyuan Yin and Erkang Wang
Analytical Chemistry 2008 Volume 80(Issue 14) pp:5635
Publication Date(Web):June 17, 2008
DOI:10.1021/ac8001462
In this work, an electrochemiluminescence (ECL) reagent bis(2,2′-bipyridine)(5,6-epoxy-5,6-dihydro-[1,10]phenanthroline)ruthenium complex (Ru-1) was synthesized, and its electrochemical and ECL properties were characterized. The synthesis of Ru-1 was confirmed by IR spectra, element analysis, and 1H NMR spectra. For further study, its UV−vis absorption and fluorescence emission spectra were investigated. Ru-1 also exhibited quasi-reversible RuII/RuIII redox waves in acetonitrile solution. The aqueous ECL behaviors of Ru-1 were also studied in the absence and in the presence of tripropylamine. The complex was fabricated on a γ-(aminopropyl) triethoxysilane (APTES) pretreated indium tin oxide (ITO) substrate via aminolysis reaction between the 5,6-epoxy-5,6-dihydro-[1,10]phenanthroline ligand and APTES. The resulting Ru-1 modified ITO substrate exhibited a broad absorption band in the visible region (350−600 nm) and its fluorescence emission spectrum was centered at 622 nm. The Ru-1 modified ITO electrode showed relative low ECL response. To improve the solid-state ECL response, a gold nanoparticles (GNP)/Ru-1 modified ITO electrode was constructed. The mixing of GNP and Ru-1 could produce the aggregates, which were further immobilized onto a 3-mercaptopropyltrimethoxy-silane (3-MPTMS) pretreated ITO substrate via Au−S interactions to construct the GNP/Ru-1 modified electrode.
Co-reporter:Yan Du, Bingling Li, Hui Wei, Yuling Wang and Erkang Wang
Analytical Chemistry 2008 Volume 80(Issue 13) pp:5110
Publication Date(Web):June 4, 2008
DOI:10.1021/ac800303c
Aptamers, which are in vitro selected functional oligonucleotides, have been employed to design novel biosensors (i.e., aptasensors) due to their inherent selectivity, affinity, and their multifarious advantages over traditional recognition elements. In this work, we reported a multifunctional reusable label-free electrochemical biosensor based on an integrated aptamer for parallel detection of adenosine triphosphate (ATP) and α-thrombin, by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A Au electrode as the sensing surface was modified with a part DNA duplex which contained a 5′-thiolated partly complementary strand (PCS) and a mixed aptamer (MBA). The unimolecular MBA contained small-molecule ATP binding aptamer (ABA) and also protein α-thrombin binding aptamer (TBA). Thus, the aptasensor could be used for detection of ATP and α-thrombin both. The detection limit of ATP was 1 × 10−8 M, and its detection range could extend up to 10−4 M, whereas the detection limit of α-thrombin was 1 × 10−11 M, and its detection range was from 1 × 10−11 to 1 × 10−7 M. Meanwhile, after detecting α-thrombin, the sensing interface could be used for ATP recognition as well. The aptasensor regeneration could be realized by rehybridizing of the MBA strand with the partly complementary strand immobilized on the Au surface after ATP detection or by treating with a large amount of ATP and then rehybridizing the MBA strand with the partly complementary strand immobilized on the Au surface after α-thrombin detection. The aptasensor fabricated exhibited several advantages such as label-free detection, high sensitivity, regeneration, and multifunctional recognition. It also showed the detectability in biological fluid. Therein it held promising potential for integration of the sensing ability such as the simultaneous detection for multianalysis in the future.
Co-reporter:Lanyun Fang, Zhaozi Lü, Hui Wei, Erkang Wang
Analytica Chimica Acta 2008 Volume 628(Issue 1) pp:80-86
Publication Date(Web):17 October 2008
DOI:10.1016/j.aca.2008.08.041
A novel electrochemiluminescence (ECL) aptasensor was proposed for sensitive and cost-effective detection of the target thrombin adopted an aptamer-based sandwich format. To detect thrombin, capture aptamers labeled with gold nanoparticles (AuNPs) were first immobilized onto the thio-silanized ITO electrode surface through strong Au–S bonds. After catching the target thrombin, signal aptamers tagged with ECL labels were attached to the assembled electrode surface. As a result, an AuNPs-capture-aptamer/thrombin/ECL-tagged-signal-aptamer sandwich type was formed. Treating the resulting electrode surface with tri-n-propylamine (TPA) and applying a swept potential to the electrode, ECL response was generated which realized the detection of target protein. Spectroscopy and electrochemical impedance techniques were used to characterize and confirm the fabrication of the ECL aptasensor. AuNPs amplification and smart sensor fabrication art were implemented for the sensitive and cost-effective detection purpose. Signal-to-dose curve excellently followed a sandwich format equation and could be used to quantify the protein, and the detection limit was estimated to be 10 nM. Other forms of thrombin such as β- and γ-thrombins had negligible response, which indicated a high specificity of α-thrombin detection. The aptasensor opened up new fields of aptamer applications in ECL domain, a highly sensitive technique, and had a promising perspective to be applied in microarray analysis.
Co-reporter:Yuanhong Xu, Bingling Li, Jing Li, Erkang Wang
Analytica Chimica Acta 2008 Volume 625(Issue 1) pp:35-40
Publication Date(Web):5 September 2008
DOI:10.1016/j.aca.2008.07.009
“Fluidic leakage” caused by vacuum force at the reversible sealing poly(dimethylsiloxane) (PDMS) interfaces was converted to one useable avenue, which led to formation of highly ordered surfactant microdroplets functionalized with ionic liquids (ILs). Vacuum force is the prerequisite to lead constant microsolutions to diffuse to the PDMS interfaces. Imidazolium ions of ILs rendered structural rearrangement of the surfactant aggregates and the ordered droplets formation. The anion tetrafluoroborate of ILs possessed indispensable functions in affecting the polarity of the microdroplets and was discovered to have enhanced effect on encapsulation of hydrophilic molecules in surfactant microdroplets. These interesting phenomena were characterized by various analytical methods such as confocal laser scanning microscopy, atomic force microscopy, luminescence spectroscopy and UV–vis spectroscopy.
Co-reporter:Yuling Wang, Shaojun Guo, Hongjun Chen, Erkang Wang
Journal of Colloid and Interface Science 2008 Volume 318(Issue 1) pp:82-87
Publication Date(Web):1 February 2008
DOI:10.1016/j.jcis.2007.09.057
An effective and facile method for fabrication of large area of aggregated gold nanorods (AuNRs) film was proposed by self-assembly of AuNRs at a toluene/water interface for the first time. It was found that large area of aggregated AuNRs film could be formed at the interface of toluene and water due to the interfacial tension between the two phases. The obtained large area of aggregated AuNRs film exhibits strong surface-enhanced Raman scattering (SERS) activity with 4-aminothiophenol (4-ATP) and 2-aminothiophenol (2-ATP) as the probe molecules based on the strong electromagnetic coupling effect between the very adjacent AuNRs. Enhancement factors (EF) were used to estimate the SERS activity of the aggregated AuNRs film, which is obtained to be 1.7×1051.7×105 for 7a vibration of 4-ATP. SERS intensity is compared with AuNRs deposited directly on glass, indicating high SERS activity and reproducibility of the aggregated AuNRs film. In addition, SERS activity has also been successfully demonstrated for dye molecule (Rhodamin 6G (R6G)) and biological small molecule (adenine) on the aggregated AuNRs film, showing great potential of the aggregated AuNRs film as a convenient and powerful SERS substrate for biological tags and biological molecular detection.Effective and facile fabrication of large area of aggregated gold nanorods film was proposed, which exhibits strong SERS activity.
Co-reporter:Hui Wei, Lingling Zhou, Jing Li, Jifeng Liu, Erkang Wang
Journal of Colloid and Interface Science 2008 Volume 321(Issue 2) pp:310-314
Publication Date(Web):15 May 2008
DOI:10.1016/j.jcis.2008.02.012
Co-reporter:Weiwei Guo, Jipei Yuan, Bingling Li, Yan Du, Erbo Ying and Erkang Wang
Analyst 2008 vol. 133(Issue 9) pp:1209-1213
Publication Date(Web):28 Jul 2008
DOI:10.1039/B806301J
A unique multilabeling at a single-site protocol of the Ru(bpy)32+ electrochemiluminescence (ECL) system is proposed. Nanoparticles (NPs) were used as assembly substrates to enrich ECL co-reactants of Ru(bpy)32+ to construct nanoscale-enhanced ECL labels. Two different kinds of NP substrates [including semiconductor NPs (CdTe) and noble metal NPs (gold)] capped with 2-(dimethylamino)ethanethiol (DMAET) [a tertiary amine derivative which is believed to be one of the most efficient of co-reactants of the Ru(bpy)32+ system] were synthesized through a simple one-pot synthesis method in aqueous media. Although both CdTe and gold NPs realized the enrichment of ECL co-reactants, they presented entirely different ECL performances as nanoscale ECL co-reactants of Ru(bpy)32+. The different effects of these two NPs on the ECL of Ru(bpy)32+ were studied. DMAET-capped CdTe NPs showed enormous signal amplification of Ru(bpy)32+ ECL, whereas DMAET-capped gold NPs showed a slight quenching effect of the ECL signal. DMAET-capped CdTe NPs can be considered to be excellent nanoscale ECL labels of the Ru(bpy)32+ system, as even a NP solution sample of 10−18 M was still detectable after an electrostatic self-assembly concentration process. DMAET-capped CdTe NPs were further applied in the construction of aptamer-based biosensing system for proteins and encouraging results were obtained.
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
Crystal Growth & Design 2008 Volume 8(Issue 10) pp:3581-3585
Publication Date(Web):August 27, 2008
DOI:10.1021/cg800023d
We first suggested a one-pot method to synthesize monodisperse raspberry-like submicrometer gold spheres (MRSGS) with high yield. The resulting gold spheres were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersed X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and electrochemical technology. It was found that the rough structure provided by raspberry-like gold spheres led to a tremendous electrochemical active area, which was very important because these novel hierarchical gold spheres will probably find important applications in biosensors, electrocatalysis, and others. The formation mechanism of the raspberry-like gold spheres was also discussed. Furthermore, we expanded a liquid−liquid interface assembling strategy to MRSGS systems and first constructed uniform raspberry-like gold sphere arrays on a solid substrate.
Co-reporter:Xiaohua Liu, Lixue Zhang, Yuling Wang, Cunlan Guo and Erkang Wang
Crystal Growth & Design 2008 Volume 8(Issue 3) pp:759-762
Publication Date(Web):February 9, 2008
DOI:10.1021/cg060812s
We report the interesting finding that crystallization of calcium carbonate (CaCO3) in the presence of dimyristoylphosphatidylglycerol (DMPG) vesicles by a simple gas diffusion method results in the formation of unusual microscopic CaCO3 spherules. The experimental results indicate that the as-prepared CaCO3 spherules, which have a complex macroporous structure, are predominantly vaterite. It is believed that DMPG vesicles play an important role in the process of crystallization, and the possible formation mechanism is proposed.
Co-reporter:Bingyan Han, Yan Du, Erkang Wang
Microchemical Journal 2008 Volume 89(Issue 2) pp:137-141
Publication Date(Web):August 2008
DOI:10.1016/j.microc.2008.01.007
In this paper, we described a simple and rapid method, capillary electrophoresis with electrochemiluminescence (CE–ECL) detection using tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+), to simultaneously detect pethidine and methadone. Analytes were injected to separation capillary of 67.5 cm length (25 μm i.d., 360 μm o.d.) by electrokinetic injection for 10 s at 10 kV. Under the optimized conditions: ECL detection at 1.20 V, 30 mM sodium phosphate (pH 6.0) as running buffer, separation voltage at 14.0 kV, 5 mM Ru(bpy)32+ with 50 mM sodium phosphate (pH 6.5) in the detection cell, the linear range from 2.0 × 10− 6 to 2.0 × 10− 5 M for pethidine and 5.0 × 10− 6 to 2.0 × 10− 4 M for methadone and detection limits of 0.5 μM for both of them were achieved (S/N = 3). Relative standard derivations of the ECL intensity were 2.09% and 6.59% for pethidine and methadone, respectively.
Co-reporter:Jin Wang, Li Xu, Kang Xue, Erkang Wang
Chemical Physics Letters 2008 Volume 463(4–6) pp:405-409
Publication Date(Web):1 October 2008
DOI:10.1016/j.cplett.2008.08.081
Abstract
We explored the origin of power law distribution observed in single-molecule conformational dynamics experiments. By establishing a kinetic master equation approach to study statistically the microscopic state dynamics, we show that the underlying landscape with exponentially distributed density of states leads to power law distribution of kinetics. The exponential density of states emerges when the system becomes glassy and landscape becomes rough with significant trapping. We predicted the power law decay coefficient is monotonically dependent on temperature which can be tested from ongoing experiments. This work bridges statistics from single-molecule kinetic experiments and topography of conformational energy landscape.
Co-reporter:Shaojun Guo, Erkang Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 317(1–3) pp:673-678
Publication Date(Web):20 March 2008
DOI:10.1016/j.colsurfa.2007.12.002
Here we present a simple wet-chemical approach to synthesize flower-like silver nanostrip assembling architecture at room temperature. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images indicate that these microstructures with the diameter of ∼500 nm exhibit hierarchical characteristic. X-ray diffraction (XRD), energy-dispersed X-ray spectroscopy (EDX) and Raman spectroscopy indicate that poly (o-diaminobenzene) (PDB) also exists in the silver hierarchical microstructure. The roles of the poly(N-vinyl-2-pyrrolidone) (PVP) concentration on the hierarchical microstructure synthesis have been systematically investigated. Due to their hierarchical characteristic and high surface-to-volume ratios, these microstructures are expected to find potential applications in bioelectrochemistry.
Co-reporter:Hui Wei;Jifeng Liu Dr.;Lingling Zhou;Jing Li;Xiue Jiang Dr.;Jianzhen Kang Dr.;Xiurong Yang ;Shaojun Dong
Chemistry - A European Journal 2008 Volume 14( Issue 12) pp:3687-3693
Publication Date(Web):
DOI:10.1002/chem.200701518
Abstract
[Ru(bpy)3]2+-doped silica (RuSi) nanoparticles were synthesized by using a water/oil microemulsion method. Stable electrochemiluminescence (ECL) was obtained when the RuSi nanoparticles were immobilized on a glassy carbon electrode by using tripropylamine (TPA) as a coreactant. Furthermore, the ECL of the RuSi nanoparticles with layer-by-layer biomolecular coatings was investigated. Squential self-assembly of the polyelectrolytes and biomolecules on the RuSi nanoparticles gave nanocomposite suspensions, the ECL of which decreased on increasing the number of bilayers. Moreover, factors that affected the assembly and ECL signals were investigated. The decrease in ECL could be assigned to steric hindrance and limited diffusion of the coreactant molecules in the silica matrix after they were attached to the biomolecules. Since surface modification of the RuSi nanoparticles can improve their biocompatibility and prevent leaking of the [Ru(bpy)3]2+ ions, the RuSi nanoparticles can be readily used as efficient and stable ECL tag materials in immunoassay and DNA detection.
Co-reporter:Tao Li;Yan Du Dr. Dr.
Chemistry – An Asian Journal 2008 Volume 3( Issue 11) pp:1942-1948
Publication Date(Web):
DOI:10.1002/asia.200800152
Abstract
Polyethyleneimine-functionalized platinum nanoparticles (PtNPs) with excellent electrochemiluminescence (ECL) properties were synthesized and applied to the amplified analysis of biomolecules. These particles were prepared at room temperature, with hyperbranched polyethyleneimine (HBPEI) as the stabilizer. The UV/Vis absorption spectra and transmission electron microscopy images clearly confirmed the formation of monodisperse PtNPs. Such particles proved to possess high stability against salt-induced aggregation, enabling them to be employed even under high-salt conditions. Owing to the existence of many tertiary amine groups, these particles exhibited excellent ECL behavior in the presence of tris(2,2′-bipyridyl)ruthenium(II). An HBPEI-coated particle possessed an ECL activity that was at least 60 times higher than that of a tripropylamine molecule. Furthermore, these particles could be immobilized on the 3-aminopropyltriethoxysilane-treated quartz substrates to amplify the binding sites for carboxyl groups. Through this approach, PtNPs were applied to the amplified analysis of the hemin/G-quadruplex DNAzyme by using the luminol/H2O2 chemiluminescence method.
Co-reporter:Shaojun Guo;Jing Li
Chemistry – An Asian Journal 2008 Volume 3( Issue 8-9) pp:1544-1548
Publication Date(Web):
DOI:10.1002/asia.200800075
Abstract
A large-scale process combined sonication with self-assembly techniques for the preparation of high-density gold nanoparticles supported on a [Ru(bpy)3]2+-doped silica/Fe3O4 nanocomposite (GNRSF) is provided. The obtained hybrid nanomaterials containing Fe3O4 spheres have high saturation magnetization, which leads to their effective immobilization on the surface of an ITO electrode through simple manipulation by an external magnetic field (without the need of a special immobilization apparatus). Furthermore, this hybrid nanomaterial film exhibits a good and very stable electrochemiluminescence (ECL) behavior, which gives a linear response for tripropylamine (TPA) concentrations between 5 μM and 0.21 mM, with a detection limit in the micromolar range. The sensitivity of this ECL sensor can be easily controlled by the amount of [Ru(bpy)3]2+ immobilized on the hybrid nanomaterials (that is, varying the amount of [Ru(bpy)3]2+ during GNRSF synthesis).
Co-reporter:Shaojun Guo;Junfeng Zhai;Youxing Fang;Shaojun Dong
Chemistry – An Asian Journal 2008 Volume 3( Issue 7) pp:1156-1162
Publication Date(Web):
DOI:10.1002/asia.200700422
Abstract
A high-efficiency nanoelectrocatalyst based on high-density Au/Pt hybrid nanoparticles supported on a silica nanosphere (Au-Pt/SiO2) has been prepared by a facile wet chemical method. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy are employed to characterize the obtained Au-Pt/SiO2. It was found that each hybrid nanosphere is composed of high-density small Au/Pt hybrid nanoparticles with rough surfaces. These small Au/Pt hybrid nanoparticles interconnect and form a porous nanostructure, which provides highly accessible activity sites, as required for high electrocatalytic activity. We suggest that the particular morphology of the Au-Pt/SiO2 may be the reason for the high catalytic activity. Thus, this hybrid nanomaterial may find a potential application in fuel cells.
Co-reporter:Jianyuan Yin, Yuanhong Xu, Jing Li, Erkang Wang
Talanta 2008 Volume 75(Issue 1) pp:38-42
Publication Date(Web):15 March 2008
DOI:10.1016/j.talanta.2007.10.003
A capillary electrophoresis method coupled with electrochemiluminescence detection for the analysis of quinolizidine alkaloids was established, especially, oxymatrine (OMT) which could not be measured by previous electrochemiluminescence methods was detected sensitively herein. Complete separation of sophoridine (SR), matrine (MT) and OMT was achieved within 13 min using a background electrolyte of 50mM phosphate buffer at pH 8.4 and a separation voltage of 15 kV. The calibration curves showed a linear range from 2.8 × 10−8 to 4.4 × 10−7 M for SR, 2.7 × 10−8 to 4.4 × 10−7 M for MT, and 2.5 × 10−7 to 4.0 × 10−6 M for OMT, respectively. The relative standard derivations for all analytes were below 3.1%. Good linear relationships were showed with correlation coefficients for all analytes exceeded 0.987. The detection limits were 1.0 nM for SR and MT, and 40 nM for OMT under the optimal conditions, respectively. The developed method was nearly harmless to the human and environment.
Co-reporter:Li Xu;Jin Wang
PNAS 2008 Volume 105 (Issue 34 ) pp:12271-12276
Publication Date(Web):2008-08-26
DOI:10.1073/pnas.0800579105
We established a theoretical framework for studying nonequilibrium networks with two distinct natures essential for characterizing
the global probabilistic dynamics: the underlying potential landscape and the corresponding curl flux. We applied the idea
to a biochemical oscillation network and found that the underlying potential landscape for the oscillation limit cycle has
a distinct closed ring valley (Mexican hat-like) shape when the fluctuations are small. This global landscape structure leads
to attractions of the system to the ring valley. On the ring, we found that the nonequilibrium flux is the driving force for
oscillations. Therefore, both structured landscape and flux are needed to guarantee a robust oscillating network. The barrier
height separating the oscillation ring and other areas derived from the landscape topography is shown to be correlated with
the escaping time from the limit cycle attractor and provides a quantitative measure of the robustness for the network. The
landscape becomes shallower and the closed ring valley shape structure becomes weaker (lower barrier height) with larger fluctuations.
We observe that the period and the amplitude of the oscillations are more dispersed and oscillations become less coherent
when the fluctuations increase. We also found that the entropy production of the whole network, characterizing the dissipation
costs from the combined effects of both landscapes and fluxes, decreases when the fluctuations decrease. Therefore, less dissipation
leads to more robust networks. Our approach is quite general and applicable to other networks, dynamical systems, and biological
evolution. It can help in designing robust networks.
Co-reporter:Y. Xu;J. Li;Y. Gao;E. Wang;T. Li;Y. Du
Advanced Functional Materials 2007 Volume 17(Issue 6) pp:1003-1009
Publication Date(Web):1 FEB 2007
DOI:10.1002/adfm.200600537
An enhanced electrochemiluminescence (ECL) efficiency is obtained from the ruthenium complex tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) by introduction of an ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4). Upon addition of 1 % (v/v) BMImBF4 to 0.1 mM Ru(bpy)32+ solution, a maximum increase in ECL intensity is obtained both at an indium tin oxide (ITO) electrode (15-fold) and at a glassy carbon (GC) electrode (5- to 6-fold). Furthermore, upon addition of 1 % (v/v) BMImBF4 to 5 μM Ru(bpy)32+/100 mM co-reactant systems at a GC electrode, IL adsorption occurs at the electrode surface, which results in a change of the polarity of the electrode surface. Such functionalization greatly improves the functions of both Ru(bpy)32+ and ionic liquids, as is demonstrated in the sensitive and selective concentration enrichment of the Ru(bpy)32+ co-reactants.
Co-reporter:Shaojun Guo, Liang Wang and Erkang Wang
Chemical Communications 2007 (Issue 30) pp:3163-3165
Publication Date(Web):25 May 2007
DOI:10.1039/B705630C
We report for the first time a simple low-cost electrochemical route to synthesis of diameter-controlled hierarchical flowerlike gold microstructures with “clean” surfaces using gold nanoplates or nanopricks as building blocks without introducing any template or surfactant.
Co-reporter:Tao Li, Shaojun Dong and Erkang Wang
Chemical Communications 2007 (Issue 41) pp:4209-4211
Publication Date(Web):28 Sep 2007
DOI:10.1039/B712165B
A DNAzyme-based label-free method for the colorimetric detection of DNA is introduced, with a supramolecular hemin–G-quartet complex as the sensing element and a 36-mer single-strand DNA as the analyte that is detected at 10 nM.
Co-reporter:Jianzhen Kang, Hui Wei, Weiwei Guo, Erkang Wang
Electrochemistry Communications 2007 Volume 9(Issue 3) pp:465-468
Publication Date(Web):March 2007
DOI:10.1016/j.elecom.2006.07.010
The electrochemiluminescence (ECL) in the S2O82- system occurs under conventional cyclic voltammetry, when the Pt working electrode was coated with Cd elementary substance. The ECL mechanism was proposed, due to the reaction between the strongly oxidizing intermediate SO4- and the transitory production, CdO, generated by oxidation of Cd with SO4-. Moreover the ECL behavior was studied in different pHs and concentrations of S2O82-solution. It was showed that the ECL signal was strongest at pH 8.0, and its intensity increased with S2O82-. The experimental results verified well with the proposed ECL mechanism.
Co-reporter:Hui Wei, Yan Du, Jianzhen Kang, Erkang Wang
Electrochemistry Communications 2007 Volume 9(Issue 7) pp:1474-1479
Publication Date(Web):July 2007
DOI:10.1016/j.elecom.2007.01.053
Label free electrochemiluminescence (ECL) DNA detection based on catalytic guanine and adenine bases oxidation using tris (2,2′-bipyridyl)ruthenium(II) [Ru(bpy)32+] modified glassy carbon (GC) electrode was demonstrated in this work. The modified GC electrode was prepared by casting carbon nanotubes (CNT)/Nafion/Ru(bpy)32+ composite film on the electrode surface. ECL signals of double-stranded DNA and their thermally denatured counterparts can be distinctly discriminated using cyclic voltammetry (CV) with a low concentration (3.04 × 10−8 mol/L for Salmon Testes-DNA). Most importantly, sensitive single-base mismatch detection of p53 gene sequence segment was realized with 3.93 × 10−10 mol/L employing CV stimulation (ECL signal of C/A mismatched DNA oligonucleotides was 1.5-fold higher than that of fully base-paired DNA oligonucleotides). Label free, high sensitivity and simplicity for single-base mismatch discrimination were the main advantages of the present ECL technique for DNA detection over the traditional DNA sensors.
Co-reporter:Liangwei Du, Hong Jiang, Xiaohua Liu, Erkang Wang
Electrochemistry Communications 2007 Volume 9(Issue 5) pp:1165-1170
Publication Date(Web):May 2007
DOI:10.1016/j.elecom.2007.01.007
In this communication, biosynthesis of gold nanoparticles assisted by Escherichia coli DH5α and its application on direct electrochemistry of hemoglobin are reported. The gold nanoparticles formed on the bacteria surface are mostly spherical. The direct electrochemistry of hemoglobin can be achieved by incorporated into the bio-nanocomposite films on a glassy carbon electrode.
Co-reporter:Shaojun Guo, Erkang Wang
Analytica Chimica Acta 2007 Volume 598(Issue 2) pp:181-192
Publication Date(Web):29 August 2007
DOI:10.1016/j.aca.2007.07.054
This review covers recent advances in synthesis and electrochemical applications of gold nanoparticles (AuNPs). Described approaches include the synthesis of AuNPs via designing and choosing new protecting ligands; and applications in electrochemistry of AuNPs including AuNPs-based bioelectrochemical sensors, such as direct electrochemistry of redox-proteins, genosensors and immunosensors, and AuNPs as enhancing platform for electrocatalysis and electrochemical sensors.
Co-reporter:Shaojun Guo, Erkang Wang
Journal of Colloid and Interface Science 2007 Volume 315(Issue 2) pp:795-799
Publication Date(Web):15 November 2007
DOI:10.1016/j.jcis.2007.07.070
The shape-controlled synthesis of micrometer-sized gold nanocoralline was simply realized via a wet-chemical approach. The as-prepared hierarchical gold nanocorallines (HGNs) on the solid substrate were initially applied in SERS analysis with 4-aminothiophenol (4-ATP) as the probe molecule. The HGN-modified glass substrate exhibits a higher SERS effect (one order of magnitude higher) than the aggregated gold nanoparticle (∼25 nm)-modified glass substrate.The shape-controlled synthesis of micrometer-sized gold nanocoralline was simply realized via a wet-chemical approach. The as-prepared hierarchical gold nanocorallines (HGNs) on the solid substrate were initially applied in SERS analysis with 4-aminothiophenol (4-ATP) as the probe molecule. The HGN-modified glass substrate exhibits a higher SERS effect (one order of magnitude higher) than the aggregated gold nanoparticle (∼25 nm)-modified glass substrate.
Co-reporter:Shaojun Guo, Liang Wang, Yuling Wang, Youxing Fang, Erkang Wang
Journal of Colloid and Interface Science 2007 Volume 315(Issue 1) pp:363-368
Publication Date(Web):1 November 2007
DOI:10.1016/j.jcis.2007.06.022
The controlled synthesis of bifunctional Au@Pt hybrid nanorods has been realized through a simple wet chemical approach. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–vis–near infrared spectroscopy (UV–vis–NIR) were employed to characterize the obtained hybrid nanorods. TEM results indicate that the thickness of Pt nanoislands on the surfaces of gold nanorods can be easily tunable via controlling the molar ratio of Au nanorods to the H2PtCl6. These Au@Pt hybrid nanorods have dual functions, which can be used not only for surface enhanced Raman spectroscopy (SERS), but also to exhibit good catalytic activity for O2 reduction. It is expected that these hybrid nanorods can be used as new functional building blocks to assemble novel three-dimensional (3D) complex multicomponent nanostructures, which are believed to be useful for electrochemical nanodevices.The controlled synthesis of bifunctional Au@Pt hybrid nanorods has been realized through a simple wet chemical approach. These Au@Pt hybrid nanorods have dual functions, which can be used not only for surface-enhanced Raman spectroscopy (SERS), but also to exhibit good catalytic activity for O2 reduction. It is expected that these hybrid nanorods can be used as new functional building blocks to assemble novel three-dimensional (3D) complex multicomponent nanostructures, which are believed to be useful for the electrochemical nanodevices.
Co-reporter:Jing Li, Minghua Huang, Xiaoqing Liu, Hui Wei, Yuanhong Xu, Guobao Xu and Erkang Wang
Analyst 2007 vol. 132(Issue 7) pp:687-691
Publication Date(Web):08 Jun 2007
DOI:10.1039/B701842H
The electrochemiluminescence (ECL) of tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)32+] ion-exchanged in the sulfonic-functionalized MCM-41 silicas was developed with tripropylamine (TPrA) as a co-reactant in a carbon paste electrode (CPE) using a room temperature ionic liquid (IL) as a binder. The sulfonic-functionalized silicas MCM-41 were used for preparing an ECL sensor by the electrostatic interactions between Ru(bpy)32+ cations and sulfonic acid groups. We used the IL as a binder to construct the CPE (IL-CPE) to replace the traditional binder of the CPE (T-CPE) – silicone oil. The results indicated that the MCM-41-modified IL-CPE had more open structures to allow faster diffusion of Ru(bpy)32+ and that the ionic liquid also acted as a conducting bridge to connect TPrA with Ru(bpy)32+ sites immobilized in the electrode, resulting in a higher ECL intensity compared with the MCM-41-modified T-CPE. Herein, the detection limit for TPrA of the MCM-41-modified IL-CPE was 7.2 nM, which was two orders of magnitude lower than that observed at the T-CPE. When this new sensor was used in flow injection analysis (FIA), the MCM-41-modified IL-CPE ECL sensor also showed good reproducibility. Furthermore, the sensor could also be renewed easily by mechanical polishing whenever needed.
Co-reporter:Shaojun Guo, Lijian Huang and Erkang Wang
New Journal of Chemistry 2007 vol. 31(Issue 4) pp:575-579
Publication Date(Web):02 Mar 2007
DOI:10.1039/B616234G
We present a simple, generally applicable procedure for obtaining diameter-controlled SiO2@ carbon nanotubes (CNTs) coaxial nanocables. These coaxial nanocables with high solubility in polar solvents, have been used as functional templates for assembling CNTs/Au nanorods heterogeneous nanostructures to form multifunctional assembly system. These hybrid nanostructures may find applications in nanoelectronics, photonics, and nanodevices.
Co-reporter:Erkang Wang;Yan Du
Journal of Separation Science 2007 Volume 30(Issue 6) pp:875-890
Publication Date(Web):20 MAR 2007
DOI:10.1002/jssc.200600472
Recent advances and key strategies in capillary electrophoresis and microchip CE with electrochemical detection (ECD) and electrochemiluminescence (ECL) detection are reviewed. This article consists of four main parts: CE–ECD; microchip CE–ECD; CE–ECL; and microchip CE–ECL. It is expected that ECD and ECL will become powerful tools for CE microchip systems and will lead to the creation of truly disposable devices. The focus is on papers published in the last two years (from 2005 to 2006).
Co-reporter:Hui Wei;Yan Du;Jian-Zhen Kang;Guo-Bao Xu;Er-Kang Wang
Chinese Journal of Chemistry 2007 Volume 25(Issue 2) pp:
Publication Date(Web):7 FEB 2007
DOI:10.1002/cjoc.200790032
An approach was reported to synthesize silica hybridized ruthenium bipyridyl complex through amidation reaction by covalent attachment of bis(bipyridyl)-4,4′-dicarboxy-2,2′-bipyridyl-ruthenium to (3-aminopropyl)-triethoxy- silane. The hybrid complex then was gelatinized through acid catalytic hydrolysis method and a sol-gel modified indium tin oxide electrode was prepared via spin coating technique. As prepared indium tin oxide electrode possesses good stability therein with excellent electrochemiluminescence behavior.
Co-reporter:Tao Li;Bingling Li;Shaojun Dong Dr. Dr.
Chemistry - A European Journal 2007 Volume 13(Issue 30) pp:
Publication Date(Web):18 JUL 2007
DOI:10.1002/chem.200700275
Herein, we report an approach for protein detection enhanced by ionic liquid (IL) selectors in capillary electrophoresis (CE), with avidin as a model protein. Hydrophilic ILs were added into the running buffer of CE and acted as selectors for sample injection, enriching the positive target and excluding the negative from the capillary. When using 3 % (v/v) IL selector, the detection sensitivity of avidin was improved by over one order of magnitude, while the interference from protein adsorption was effectively avoided, even in an uncoated capillary. The electrochemiluminescence method was initially used for IL-based CE with low noise that was independent of the IL concentration, making ILs almost transparent as additives in the electrophoresis buffer.
Co-reporter:Xuping Sun Dr.;Lixue Zhang;Yan Du;Shaojun Dong
Chemistry – An Asian Journal 2007 Volume 2(Issue 9) pp:1137-1141
Publication Date(Web):6 JUL 2007
DOI:10.1002/asia.200700002
Tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)3]2+) is one of the most extensively studied and used electrochemiluminescent (ECL) compounds owing to its superior properties, which include high sensitivity and stability under moderate conditions in aqueous solution. In this paper we present a simple method for the preparation of [Ru(bpy)3]2+-containing microstructures based on electrostatic assembly. The formation of such microstructures occurs in a single process by direct mixing of aqueous solutions of [Ru(bpy)3]Cl2 and K3[Fe(CN)6] at room temperature. The electrostatic interactions between [Ru(bpy)3]2+ cations and [Fe(CN)6]3− anions cause them to assemble into the resulting microstructures. Both the molar ratio and concentration of reactants were found to have strong influences on the formation of these microstructures. Most importantly, the resulting [Ru(bpy)3]2+-containing microstructures exhibit excellent ECL behavior and, therefore, hold great promise for solid-state ECL detection in capillary electrophoresis (CE) or CE microchips.
Co-reporter:Xiaohua Liu, Haixin Bai, Weimin Huang, Liangwei Du, Xiurong Yang, Erkang Wang
Electrochimica Acta 2006 Volume 51(Issue 12) pp:2512-2517
Publication Date(Web):25 February 2006
DOI:10.1016/j.electacta.2005.07.034
The interaction of chlorpromazine (CPZ) with supported bilayer lipid (dipalmitoyphosphatidylcholine) membrane (s-BLM) on the glassy carbon electrode (GCE) was investigated using cyclic voltammetry and ac impedance spectroscopy. The experimental data, based on the voltammetric response of Ru(NH3)63+ associated with the oxidation of CPZ on the electrode, indicated that the interaction of CPZ with s-BLM was concentration and time dependant. The interaction between them could be divided into three stages by the concentration of CPZ: low, middle and high concentration. At the first stage, s-BLM was not affected by CPZ and the interaction was only a penetration of a small quantity of CPZ molecule into s-BLM. At the second stage, the defects formed in s-BLM due to the penetration of more CPZ molecule into s-BLM. At the last stage, a high CPZ:lipid ratio reached in s-BLM, resulting in the solubilization of s-BLM. The interaction time had different effect at three stages.
Co-reporter:Liangwei Du, Xiaohua Liu, Weimin Huang, Erkang Wang
Electrochimica Acta 2006 Volume 51(Issue 26) pp:5754-5760
Publication Date(Web):15 August 2006
DOI:10.1016/j.electacta.2006.03.009
Ibuprofen is a well-known nonsteroidal anti-inflammatory drug, which can interact with lipid membranes. In this paper, the interaction of ibuprofen with bilayer lipid membrane was studied by UV–vis spectroscopy, cyclic voltammetry and AC impedance spectroscopy. UV–vis spectroscopy data indicated directly that ibuprofen could interact with lipid vesicles. In electrochemical experiments, ibuprofen displayed a biphasic behavior on bilayer lipid membrane supported on a glassy carbon electrode. It could stabilize the lipid membrane in low concentration, while it induced defects formation, even removed off bilayer lipid membrane from the surface of the electrode with increasing concentration. The mechanism about the interaction between ibuprofen and supported bilayer lipid membrane was discussed.
Co-reporter:Yuanhong Xu, Ying Gao, Hui Wei, Yan Du, Erkang Wang
Journal of Chromatography A 2006 Volume 1115(1–2) pp:260-266
Publication Date(Web):19 May 2006
DOI:10.1016/j.chroma.2006.02.084
Capillary electrophoresis (CE) with Ru(bpy)32+ electrochemiluminescence (ECL) detection system was established to the determination of contamination of banknotes with controlled drugs and a high efficiency on-column field-amplified sample stacking (FASS) technique was also optimized to increase the ECL intensity. The method was illustrated using heroin and cocaine, which are two typical and popular illicit drugs. Highest sample stacking was obtained when 0.01 mM acetic acid was chosen for sample dissolution with electrokinetical injection for 6 s at 17 kV. Under the optimized conditions: ECL detection at 1.2 V, separation voltage 10.0 kV, 20 mM phosphate–acetate (pH 7.2) as running buffer, 5 mM Ru(bpy)32+ with 50 mM phosphate–acetate (pH 7.2) in the detection cell, the standard curves were linear in the range of 7.50 × 10−8 to 1.00 × 10−5 M for heroin and 2.50 × 10−7 to 1.00 × 10−4 M for cocaine and detection limits of 50 nM for heroin and 60 nM for cocaine were achieved (S/N = 3), respectively. Relative standard derivations of the ECL intensity and the migration time were 3.50 and 0.51% for heroin and 4.44 and 0.12% for cocaine, respectively. The developed method was successfully applied to the determination of heroin and cocaine on illicit drug contaminated banknotes without any damage of the paper currency. A baseline resolution for heroin and cocaine was achieved within 6 min.
Co-reporter:Xiaohua Liu, Li Shang, Xiue Jiang, Shaojun Dong, Erkang Wang
Biophysical Chemistry 2006 Volume 121(Issue 3) pp:218-223
Publication Date(Web):1 June 2006
DOI:10.1016/j.bpc.2005.12.015
Conformational changes of β-lactoglobulin (β-LG) induced by anionic phospholipid (dimyristoylphosphatidylglycerol, DMPG) at physiological conditions (pH 7.0) have been investigated by UV–VIS, circular dichroism (CD) and fluorescence spectra. The experimental results suggest that β-LG–DMPG interactions cause β-LG a structural reorganization of the secondary structure elements accompanied by an increase in α-helical content, and a loosening of the protein tertiary structure. The interaction forces between β-LG and DMPG are further evaluated by fluorescence spectra. The fluorescence spectral data show that conformational changes in the protein are driven by electrostatic interaction at first, then by hydrophobic interaction between a protein with a negative net charge and a negatively charged phospholipid.
Co-reporter:Xuping Sun, Shaojun Dong, Erkang Wang
Materials Chemistry and Physics 2006 Volume 96(Issue 1) pp:29-33
Publication Date(Web):10 March 2006
DOI:10.1016/j.matchemphys.2005.06.046
Polyelectrolytes have been widely used as building blocks for the creation of thickness-controllable multilayer thin films in a layer-by-layer fashion, and also been used as flocculants or stabilizer of colloids. This paper reports novel finding that a kind of polyelectrolyte, polyamines, can facilely induce HAuCl4 to spontaneously form well-stabilized gold nanoparticles without the additional step of introducing a reducing reagent during the elevation of temperature, even at room temperature in some cases. The polymer chain-confined microenvironment and the acid-induced evolution of amide of such kind of polyelectrolyte solution play an important role in the nucleation and growth of gold nanoparticles. This method would not only be helpful to gain an insight into the formation of gold nanoparticles in polyelectrolyte systems, but also provide a novel and facile one-step polyelectrolyte-based synthetic route to polyelectrolyte protected gold nanoparticles in aqueous media for potential applications. More importantly, this strategy will be general to the preparation of other nanoparticles.
Co-reporter:Xuping Sun;Shaojun Dong;Shaojun Dong;Xuping Sun
Macromolecular Rapid Communications 2005 Volume 26(Issue 18) pp:1504-1508
Publication Date(Web):8 SEP 2005
DOI:10.1002/marc.200500502
Summary: Uniform one-dimensional (1D) structures of o-phenylenediamine (oPD) oligomers are obtained by direct mix of AgNO3 and oPD aqueous solutions at room temperature. The formation of the 1D structures involves two stages: (1) oxidation of oPD by AgNO3, yielding individual oPD oligomers; and (2) self-assembly of the oligomers, forming the 1D structures. Upon decreasing medium pH, the 1D structures can break-apart to form individual oligomers, or vice versa. It is also found that both the concentration and molar ratio of reactants can influence the morphology of the structures thus formed.
Co-reporter:Jianzhen Kang, Jilin Yan, Jifeng Liu, Haibo Qiu, Xue-Bo Yin, Xiurong Yang, Erkang Wang
Talanta 2005 Volume 66(Issue 4) pp:1018-1024
Publication Date(Web):15 May 2005
DOI:10.1016/j.talanta.2005.01.002
In this paper a method was described about dynamic coating for resolving rhodamine B (RB) adsorption on a hybrid poly(dimethylsiloxane) (PDMS)/glass chip. The results showed that when the non-ionic surfactant Triton X-100 was higher than 0.5% (v/v) into the phosphate buffer, the adsorption of RB appeared. Besides, some separation conditions for RB were investigated, including concentration of Triton X-100, concentration and pH value of running buffer, separation voltage and detection site. Through comparing electroosmotic flow, plate numbers and other parameters, an acceptable separation condition was obtained. Under optimized conditions, the precisions of RB detection (R.S.D., n = 10) were 2.62% for migration time, 4.78% for peak height respectively. Additionally, RB concentration linearity response was excellent with 0.9996 of correlation coefficient between 1 and 100 μM, and a limit of detection (S/N = 3) was 0.2 μM. Finally, we separated rhodamine B isothiocyanate and lysine deriving from the fluorescent probe, and the result displayed that the dynamic coating method was applicable by CE separations using PDMS/glass chip.
Co-reporter:Xuping Sun, Shaojun Dong and Erkang Wang
Chemical Communications 2004 (Issue 10) pp:1182-1183
Publication Date(Web):23 Apr 2004
DOI:10.1039/B401777C
We reported the interesting finding that large scale uniform poly(o-phenylenediamine) nanobelts with several hundred micrometers in length, several hundred nanometers in width, and several ten nanometers in height can be rapidly yielded from an o-phenylenediamine–HAuCl4 aqueous solution without the additional introduction of other templates or surfactants at room temperature.
Co-reporter:Aiguo Wu, Lihua Yu, Zhuang Li, Huanming Yang, Erkang Wang
Analytical Biochemistry 2004 Volume 325(Issue 2) pp:293-300
Publication Date(Web):15 February 2004
DOI:10.1016/j.ab.2003.11.005
A circular bacterial artificial chromosome of 148.9 kbp on human chromosome 3 has been extended and fixed on bare mica substrates using a developed fluid capillary flow method in evaporating liquid drops. Extended circular DNA molecules were imaged with an atomic force microscope (AFM) under ambient conditions. The measured total lengths of the whole DNA molecules were in agreement with sequencing analysis data with an error range of ±3.6%. This work is important groundwork for probing single nucleotide polymorphisms in the human genome, mapping genomic DNA, manipulating biomolecular nanotechnology, and studying the interaction of DNA–protein complexes investigated by AFM.
Co-reporter:Xuping Sun Dr.;Shaojun Dong
Angewandte Chemie International Edition 2004 Volume 43(Issue 46) pp:
Publication Date(Web):23 NOV 2004
DOI:10.1002/anie.200461013
The chemical reduction of H[AuCl4] with ortho-phenylenediamine in aqueous media at room temperature and ambient pressure allows the synthesis of Au nanoplates with lengths of several micrometers (see SEM image). The as-prepared nanoplates are single crystals with a preferential growth direction along the Au (111) plane and mainly hexagonal in shape.
Co-reporter:Xuping Sun Dr.;Shaojun Dong
Angewandte Chemie 2004 Volume 116(Issue 46) pp:
Publication Date(Web):23 NOV 2004
DOI:10.1002/ange.200461013
Die chemische Reduktion von H[AuCl4] mit ortho-Phenylendiamin in wässriger Phase bei Raumtemperatur und Normaldruck ermöglicht die Synthese von einige Mikrometer langen Au-Nanotäfelchen (siehe SEM-Bild). Die Täfelchen fallen als Einkristalle mit einer Vorzugswachsrichtung entlang der Au-(111)-Ebene und vorwiegend hexagonaler Form an.
Co-reporter:Li Wang, Yonghai Song, Bailin Zhang, Erkang Wang
Thin Solid Films 2004 Volume 458(1–2) pp:197-202
Publication Date(Web):30 June 2004
DOI:10.1016/j.tsf.2004.01.043
The adsorption behavior of methanol, ethanol, n-butanol, n-hexanol and n-octanol on mica surface was investigated by atomic force microscopy. All these alcohols have formed homogeneous films with different characteristics. Upright standing bilayer structure was formed on methanol adsorbed mica surface. For ethanol, bilayer structure and monolayer one were simultaneously formed, while for n-butanol and n-hexanol, rough films were observed. What was formed for n-octanol? Close-packed flat film was observed on n-octanol adsorbed mica substrate, the film was assumed to be a tilted monolayer. The possible adsorption model for each alcohol molecule was proposed according to its adsorption behavior.
Co-reporter:Xuping Sun;Shaojun Dong;Xiue Jiang
Macromolecular Rapid Communications 2003 Volume 24(Issue 17) pp:1024-1028
Publication Date(Web):14 NOV 2003
DOI:10.1002/marc.200300093
Dendrimer-protected gold nanoparticles have been facilely obtained by heating an aqueous solution containing third-generation poly(propyleneimine) dendrimers and HAuCl4 without the additional step of introducing other reducing agents. Transmission electron microscopy (TEM) and UV-vis data indicate the size, the nucleation, and growth kinetics of gold nanoparticles thus formed, which can be tuned by changing the initial molar ratio of dendrimer to gold.
Co-reporter:Jin Wang, Li Xu, Erkang Wang, Sui Huang
Biophysical Journal (7 July 2010) Volume 99(Issue 1) pp:
Publication Date(Web):7 July 2010
DOI:10.1016/j.bpj.2010.03.058
Differentiation from a multipotent stem or progenitor state to a mature cell is an essentially irreversible process. The associated changes in gene expression patterns exhibit time-directionality. This “arrow of time” in the collective change of gene expression across multiple stable gene expression patterns (attractors) is not explained by the regulated activation, the suppression of individual genes which are bidirectional molecular processes, or by the standard dynamical models of the underlying gene circuit which only account for local stability of attractors. To capture the global dynamics of this nonequilibrium system and gain insight in the time-asymmetry of state transitions, we computed the quasipotential landscape of the stochastic dynamics of a canonical gene circuit that governs branching cell fate commitment. The potential landscape reveals the global dynamics and permits the calculation of potential barriers between cell phenotypes imposed by the circuit architecture. The generic asymmetry of barrier heights indicates that the transition from the uncommitted multipotent state to differentiated states is inherently unidirectional. The model agrees with observations and predicts the extreme conditions for reprogramming cells back to the undifferentiated state.
Co-reporter:Chunhe Li, Erkang Wang, Jin Wang
Biophysical Journal (21 September 2011) Volume 101(Issue 6) pp:
Publication Date(Web):21 September 2011
DOI:10.1016/j.bpj.2011.08.012
Circadian rhythms with a period of ∼24 h, are natural timing machines. They are broadly distributed in living organisms, such as Neurospora, Drosophila, and mammals. The underlying natures of the rhythmic behavior have been explored by experimental and theoretical approaches. However, the global and physical natures of the oscillation under fluctuations are still not very clear. We developed a landscape and flux framework to explore the global stability and robustness of a circadian oscillation system. The potential landscape of the network is uncovered and has a global Mexican-hat shape. The height of the Mexican-hat provides a quantitative measure to evaluate the robustness and coherence of the oscillation. We found that in nonequilibrium dynamic systems, not only the potential landscape but also the probability flux are important to the dynamics of the system under intrinsic noise. Landscape attracts the systems down to the oscillation ring while flux drives the coherent oscillation on the ring. We also investigated the phase coherence and the entropy production rate of the system at different fluctuations and found that dissipations are less and the coherence is higher for larger number of molecules. We also found that the power spectrum of autocorrelation functions show resonance peak at the frequency of coherent oscillations. The peak is less prominent for smaller number of molecules and less barrier height and therefore can be used as another measure of stability of oscillations. As a consequence of nonzero probability flux, we show that the three-point correlations from the time traces show irreversibility, providing a possible way to explore the flux from the observations. Furthermore, we explored the escape time from the oscillation ring to outside at different molecular number. We found that when barrier height is higher, escape time is longer and phase coherence of oscillation is higher. Finally, we performed the global sensitivity analysis of the underlying parameters to find the key network wirings responsible for the stability of the oscillation system.
Co-reporter:Zuojia Liu, Xiliang Zheng, Xiurong Yang, Erkang Wang, Jin Wang
Biophysical Journal (20 May 2009) Volume 96(Issue 10) pp:
Publication Date(Web):20 May 2009
DOI:10.1016/j.bpj.2008.12.3965
The affinity and specificity of drugs with human serum albumin (HSA) are crucial factors influencing the bioactivity of drugs. To gain insight into the carrier function of HSA, the binding of levamlodipine with HSA has been investigated as a model system by a combined experimental and theoretical/computational approach. The fluorescence properties of HSA and the binding parameters of levamlodipine indicate that the binding is characterized by one binding site with static quenching mechanism, which is related to the energy transfer. As indicated by the thermodynamic analysis, hydrophobic interaction is the predominant force in levamlodipine-HSA complex, which is in agreement with the computational results. And the hydrogen bonds can be confirmed by computational approach between levamlodipine and HSA. Compared to predicted binding energies and binding energy spectra at seven sites on HSA, levamlodipine binding HSA at site I has a high affinity regime and the highest specificity characterized by the largest intrinsic specificity ratio (ISR). The binding characteristics at site I guarantee that drugs can be carried and released from HSA to carry out their specific bioactivity. Our concept and quantification of specificity is general and can be applied to other drug-target binding as well as molecular recognition of peptide-protein, protein-protein, and protein-DNA interactions.
Co-reporter:Jin Wang, Li Xu, Erkang Wang
Biophysical Journal (2 December 2009) Volume 97(Issue 11) pp:
Publication Date(Web):2 December 2009
DOI:10.1016/j.bpj.2009.09.021
Three-protein circadian oscillations in cyanobacteria sustain for weeks. To understand how cellular oscillations function robustly in stochastic fluctuating environments, we used a stochastic model to uncover two natures of circadian oscillation: the potential landscape related to steady-state probability distribution of protein concentrations; and the corresponding flux related to speed of concentration changes which drive the oscillations. The barrier height of escaping from the oscillation attractor on the landscape provides a quantitative measure of the robustness and coherence for oscillations against intrinsic and external fluctuations. The difference between the locations of the zero total driving force and the extremal of the potential provides a possible experimental probe and quantification of the force from curl flux. These results, correlated with experiments, can help in the design of robust oscillatory networks.
Co-reporter:Jin Wang, Li Xu, Erkwang Wang
Biophysical Journal (15 June 2007) Volume 92(Issue 12) pp:
Publication Date(Web):15 June 2007
DOI:10.1529/biophysj.107.105551
Biomolecular associations often accompanied by large conformational changes, sometimes folding and unfolding. By exploring an exactly solvable model, we constructed the free energy landscape and established a general framework for studying the biomolecular flexible binding process. We derived an optimal criterion for the specificity and function for flexible biomolecular binding where the binding and conformational folding are coupled.
Co-reporter:Dan Li, Zuojia Liu, Wenjing Zhao, Xiliang Zheng, Jin Wang, Erkang Wang
European Journal of Pharmaceutical Sciences (12 March 2013) Volume 48(Issues 4–5) pp:658-667
Publication Date(Web):12 March 2013
DOI:10.1016/j.ejps.2012.12.023
Pancreatic cancer is one of the most malignant tumor diseases with the characters of aggressive growth and metastasis. With the inefficiency of the current therapeutics, new potential targets and new therapeutic agents for healing of pancreatic cancer are critically needed. We have previously found a small molecule, named 4-tert-butyl-2-[(cyclohexylamino) methyl]-6-methylphenol (TBMMP, NSC number: 48160), which can freeze the intermediate of Ras-GTP hydrolysis in the open non-signaling conformation with high affinity and high specificity in silico. In this work, we studied the effect and mechanism of TBMMP on two pancreatic cancer cell lines, CFPAC-1 and BxPC-3. The results showed that TBMMP could restrain the growth of the pancreatic cancer cells with IC50 value 84.3 μM for CPFAC-1 and 94.5 μM for BxPC-3, respectively. Additionally, TBMMP increased cytochrome c release, reduced mitochondrial membrane potential, activated caspase-3, -9, elevated ROS and increased expression of the Bax in the pancreatic cancer cell lines. The results indicated that TBMMP induced the apoptosis of pancreatic cancer cells through the mitochondrial pathway. Further, we also found that TBMMP could suppress the metastasis of both pancreatic cancer cells in vitro. Taken together, we proposed that TBMMP might be a therapeutic potential lead for treating patients with pancreatic cancer.Download high-res image (155KB)Download full-size image
Co-reporter:Youxing Fang and Erkang Wang
Chemical Communications 2013 - vol. 49(Issue 83) pp:NaN9539-9539
Publication Date(Web):2013/08/14
DOI:10.1039/C3CC44735A
In recent years, graphene, the two-dimensional closely packed honeycomb carbon lattice, has been attracting much attention in the field of electrochemistry due to its intrinsic properties and merits. Efforts to create novel graphene based electrochemical biosensors have led to the establishment of effective strategies for diverse bioassays, from simple molecules to complex biotargets. In this Feature Article, we provide an overview of electrochemical biosensing with graphene related materials, and discuss the role of graphene in different sensing protocols.
Co-reporter:Xuan Yang, Linfeng Gan, Chengzhou Zhu, Baohua Lou, Lei Han, Jin Wang and Erkang Wang
Chemical Communications 2014 - vol. 50(Issue 2) pp:NaN236-236
Publication Date(Web):2013/10/29
DOI:10.1039/C3CC47712F
We report a high-yield strategy for the synthesis of very small silver nanoclusters (2 to 5 silver atoms) formed from conventional silver salts and scaffolds as high-performance catalysts for oxygen reduction reaction (ORR). The work demonstrates that Ag NCs are excellent catalysts for ORR and show great potential in alkaline fuel cells.
Co-reporter:Xiaofang Jia, Xuan Yang, Jing Li, Dongyue Li and Erkang Wang
Chemical Communications 2014 - vol. 50(Issue 2) pp:NaN239-239
Publication Date(Web):2013/10/30
DOI:10.1039/C3CC47771A
Highly luminescent and stable Cu nanoclusters (NCs) have been prepared, displaying an intriguing aggregation-induced emission (AIE) feature. The attractive AIE feature allowed the CuNCs to serve as pH stimuli-responsive functional materials. Additionally, we explored the utility of CuNCs for biosensing and catalysis applications.
Co-reporter:Li Yang, Qingfeng Zhai, Guijuan Li, Hong Jiang, Lei Han, Jiahai Wang and Erkang Wang
Chemical Communications 2013 - vol. 49(Issue 97) pp:NaN11417-11417
Publication Date(Web):2013/10/14
DOI:10.1039/C3CC45841E
A new approach is proposed for accurate measurement of the pore sizes in a track-etched PET membrane (polyethylene terephthalate) from a nanometer scale to a submicrometer scale, which only entailed UV-Vis spectrometry.
Co-reporter:Jinbo Zhu, Libing Zhang, Zhixue Zhou, Shaojun Dong and Erkang Wang
Chemical Communications 2014 - vol. 50(Issue 25) pp:NaN3323-3323
Publication Date(Web):2014/02/04
DOI:10.1039/C3CC49833F
A molecular aptamer beacon tuned DNA strand displacement reaction was introduced in this work. This strand displacement mode can be used to transform the adenosine triphosphate (ATP) input into a DNA strand output signal for the downstream gates to process. A simple logic circuit was built on the basis of this mechanism.
Co-reporter:Xuan Yang, Linfeng Gan, Lei Han, Dan Li, Jin Wang and Erkang Wang
Chemical Communications 2013 - vol. 49(Issue 23) pp:NaN2304-2304
Publication Date(Web):2013/02/01
DOI:10.1039/C3CC00200D
A facile synthesis of chiral penicillamine protected Au nanoclusters with different optical properties has been reported. We have for the first time observed the reversal of CD signals after the scaffolds adsorbed onto the surface of Au NCs. Such Au NCs are utilized for bioimaging due to their low cytotoxicity and stable fluorescence emission.
Co-reporter:Xiaowei Zhang, Jing Li, Chaogui Chen, Baohua Lou, Lingling Zhang and Erkang Wang
Chemical Communications 2013 - vol. 49(Issue 37) pp:NaN3868-3868
Publication Date(Web):2013/03/19
DOI:10.1039/C3CC40905H
A self-powered 3D microfluidic electrochemiluminescence biosensing platform, integrated with a stable, environmentally-friendly and noble metal-free primary battery, was developed for the first time based on the principle of origami.
Co-reporter:Jinbo Zhu, Xuan Yang, Libing Zhang, Lingling Zhang, Baohua Lou, Shaojun Dong and Erkang Wang
Chemical Communications 2013 - vol. 49(Issue 48) pp:NaN5461-5461
Publication Date(Web):2013/04/29
DOI:10.1039/C3CC42028K
A novel visible multi-digit DNA keypad lock system was fabricated based on split G-quadruplex DNAzyme and silver microspheres. The final result of the keypad lock can be easily recognized by the naked eye and the number of inputs for the keypad lock can be flexibly adjusted. This molecular platform showed excellent scalability and flexibility.
Co-reporter:Yinan Qin, Lei Xu, Jiangtao Ren, Yaqing Liu and Erkang Wang
Chemical Communications 2011 - vol. 47(Issue 29) pp:NaN8234-8234
Publication Date(Web):2011/06/21
DOI:10.1039/C1CC11993A
Three kinds of redox-mediated behavior were realized at an azobenzene-functionalized electrode, which has great potential for application in the field of molecular devices. According to these results, the functionalized electrode could act as either a cathodic molecular rectifier or anodic molecular rectifier.
Co-reporter:Shaojun Guo, Shaojun Dong and Erkang Wang
Chemical Communications 2010 - vol. 46(Issue 11) pp:NaN1871-1871
Publication Date(Web):2010/01/13
DOI:10.1039/B922148D
We for the first time report a facile, wet-chemical strategy for the high-yield (∼100%) synthesis of ultralong Pt-on-Pd bimetallic nanowires (NWs) with the cores being Pd NWs and the shells being made of dendritic Pt, which exhibit high surface area and enhanced electrocatalytic activity towards methanol oxidation reaction.
Co-reporter:Yan Du, Shaojun Guo, Haixia Qin, Shaojun Dong and Erkang Wang
Chemical Communications 2012 - vol. 48(Issue 6) pp:NaN801-801
Publication Date(Web):2011/11/03
DOI:10.1039/C1CC15303J
A new electrochemical label-free biosensor based on target-induced conjunction of a split aptamer as new chiral selector for oligopeptide using graphene–mesoporous silica–gold NP hybrids (GSGHs) as magnified sensing platform is firstly reported, which showed high sensitivity and selectivity for the detection of D-vasopressin (D-VP).
Co-reporter:Yaqing Liu, Jiangtao Ren, Yinan Qin, Jing Li, Jiyang Liu and Erkang Wang
Chemical Communications 2012 - vol. 48(Issue 6) pp:NaN804-804
Publication Date(Web):2011/12/05
DOI:10.1039/C1CC15979H
An aptamer-based security system mimicking keypad lock function was successfully designed. The system was turned “ON” with a strong fluorescent output signal only when the inputs were added according to the correct combination and exact sequence. Otherwise, the system was kept “OFF” to prevent illegal access.
Co-reporter:Hailong Li, Dan Li, Jiyang Liu, Yinan Qin, Jiangtao Ren, Shanling Xu, Yaqing Liu, Dirk Mayer and Erkang Wang
Chemical Communications 2012 - vol. 48(Issue 20) pp:NaN2596-2596
Publication Date(Web):2012/01/10
DOI:10.1039/C2CC17591F
Signal amplification originating from electrochemical current rectifier (ECR) was firstly applied to construct a cytosensor for rapid and non-invasive detection of folate receptor-rich cancer cells with high sensitivity. It exhibits a broad linear range with a detection limit as low as 10 cells mL−1 even in the presence of a large number of normal cells.
Co-reporter:Weiwei Guo, Jipei Yuan and Erkang Wang
Chemical Communications 2012 - vol. 48(Issue 25) pp:NaN3078-3078
Publication Date(Web):2012/02/01
DOI:10.1039/C2CC17155D
A unique heterophase ligand exchange induced etching process was used to transform gold nanoparticles into organic-soluble fluorescent gold clusters which were assigned to Au8 by optical spectroscopy and MALDI-TOF mass spectrometry. Both the annihilation electrochemiluminescence of fluorescent Au8 clusters in organic solution and the coreactant electrochemiluminescence of Au8 cluster film in aqueous solution were studied.
Co-reporter:Jinbo Zhu, Libing Zhang and Erkang Wang
Chemical Communications 2012 - vol. 48(Issue 98) pp:NaN11992-11992
Publication Date(Web):2012/10/29
DOI:10.1039/C2CC36693B
A special DNA calliper made of a split G-quadruplex was constructed to measure the length of DNA in a single-digit base number range between two selected sequences. The enhanced fluorescence of PPIX changed with the distance between two G-rich segments.
Co-reporter:Weiwei Guo, Jipei Yuan and Erkang Wang
Chemical Communications 2009(Issue 23) pp:NaN3397-3397
Publication Date(Web):2009/04/27
DOI:10.1039/B821518A
Fluorescent oligonucleotide-stabilized Ag nanoclusters are demonstrated as novel and environmentally-friendly fluorescence probes for the determination of Hg2+ ions with a low detection limit and high selectivity.
Co-reporter:Libing Zhang, Bingyan Han, Tao Li and Erkang Wang
Chemical Communications 2011 - vol. 47(Issue 11) pp:NaN3101-3101
Publication Date(Web):2011/01/24
DOI:10.1039/C0CC04523C
We developed a label-free fluorescent Pb2+ sensor utilizing a DNAzyme-based fluorescing molecular switch, which enables fluorescence detection of Pb2+ in aqueous solution with high sensitivity and selectivity.
Co-reporter:Jiangtao Ren, Jiahai Wang, Lei Han, Erkang Wang and Jin Wang
Chemical Communications 2011 - vol. 47(Issue 38) pp:NaN10565-10565
Publication Date(Web):2011/08/22
DOI:10.1039/C1CC13973H
Kinetically grafting G-quadruplexes onto one-dimensional DNA nanostructures with precise positioning was realized in this study. The programs hold great promise for label-free and enzyme-free detection of various targets as a result of signal amplification from G-quadruplexes, and building DNA nanostructures as scaffolds due to the molecular recognition capacity of G-quadruplex aptamers.
Co-reporter:Xuan Yang, Yan Du, Dan Li, Zhaozi Lv and Erkang Wang
Chemical Communications 2011 - vol. 47(Issue 38) pp:NaN10583-10583
Publication Date(Web):2011/04/21
DOI:10.1039/C1CC11374G
A new kind of silver micro-dendrites have been synthesized for the separation and multiplex detection of DNA merely by earth gravity. Through this approach, the DNA strands of the sickle cell disease, human T-lymphotropic virus type I, the anthrax lethal factor can be detected down to 100 pM with the detection range from 100 pM to 100 nM at the same time.
Co-reporter:Weiwei Guo, Jipei Yuan and Erkang Wang
Chemical Communications 2011 - vol. 47(Issue 39) pp:NaN10932-10932
Publication Date(Web):2011/09/12
DOI:10.1039/C1CC11921D
The fluorescence (FL)“off–on” switching of designed DNA duplex stabilized silver nanoclusters can be accomplished through the control of DNA strand exchange reaction. The successful sequential control of the FL emission of silver nanoclusters in “off–on” switching cycles confirms that the DNA duplex stabilized silver nanoclusters can work as a new kind of DNA FL switch.
Co-reporter:Libing Zhang, Tao Li, Bingling Li, Jing Li and Erkang Wang
Chemical Communications 2010 - vol. 46(Issue 9) pp:NaN1478-1478
Publication Date(Web):2010/01/20
DOI:10.1039/B921191H
Mercury ion (Hg2+) is able to specifically bind to the thymine–thymine (T–T) base pair in a DNA duplex and single-walled carbon nanotubes (SWNTs) can effectively quench fluorescence of the dye tethered to the DNA, which enables fluorescent detection of Hg2+ in aqueous solution with high selectivity and sensitivity.
Co-reporter:Liu Deng, Shaojun Guo, Zuojia Liu, Ming Zhou, Dan Li, Ling Liu, Gaiping Li, Erkang Wang and Shaojun Dong
Chemical Communications 2010 - vol. 46(Issue 38) pp:NaN7174-7174
Publication Date(Web):2010/08/18
DOI:10.1039/C0CC01371D
A significant increase (ca. 22-fold) in the electricity generation due to a Shewanella oneidensis MR-1 biofilm was observed in the presence of Fe3O4/Au nanocomposites.
Co-reporter:Xuan Yang, Xuping Sun, Zhaozi Lv, Weiwei Guo, Yan Du and Erkang Wang
Chemical Communications 2010 - vol. 46(Issue 46) pp:NaN8820-8820
Publication Date(Web):2010/10/18
DOI:10.1039/C0CC03280H
A new kind of silver micro-dendrites with no surfactants protected has been synthesized for the separation and detection of DNA merely by earth gravity as the density of silver is larger than that of water. Through this approach, the DNA of human T-lymphotropic virus type I (HTLV-I) can be detected down to 10 pM with the detection range from 10 pM to 100 nM.
Co-reporter:Tao Li, Bingling Li, Erkang Wang and Shaojun Dong
Chemical Communications 2009(Issue 24) pp:NaN3553-3553
Publication Date(Web):2009/05/07
DOI:10.1039/B903993G
Hg2+ is able to inhibit the peroxidase-like DNAzyme function of a T-containing G-quadruplex DNAviaHg2+-mediated T–T base pairs, which enables the visual detection of Hg2+ in the TMB–H2O2 reaction system with high selectivity and sensitivity.
Co-reporter:Shaojun Guo, Liang Wang and Erkang Wang
Chemical Communications 2007(Issue 30) pp:NaN3165-3165
Publication Date(Web):2007/05/25
DOI:10.1039/B705630C
We report for the first time a simple low-cost electrochemical route to synthesis of diameter-controlled hierarchical flowerlike gold microstructures with “clean” surfaces using gold nanoplates or nanopricks as building blocks without introducing any template or surfactant.
Co-reporter:Tao Li, Shaojun Dong and Erkang Wang
Chemical Communications 2007(Issue 41) pp:NaN4211-4211
Publication Date(Web):2007/09/28
DOI:10.1039/B712165B
A DNAzyme-based label-free method for the colorimetric detection of DNA is introduced, with a supramolecular hemin–G-quartet complex as the sensing element and a 36-mer single-strand DNA as the analyte that is detected at 10 nM.
Co-reporter:Libing Zhang, Jinbo Zhu, Zhixue Zhou, Shaojun Guo, Jing Li, Shaojun Dong and Erkang Wang
Chemical Science (2010-Present) 2013 - vol. 4(Issue 10) pp:NaN4010-4010
Publication Date(Web):2013/07/10
DOI:10.1039/C3SC51303C
Dynamic DNA assembly, operated in an autonomous and reconfigurable manner by controlling the kinetics of strand displacement reactions (SDR), is an ideal approach to amplify the fluorescent signals for molecular diagnostic and imaging. Herein, we for the first time have demonstrated an enhancement of fluorescence intensity of DNA/Ag nanocluster-based beacons by the modulation of SDR. This is a new DNA/Ag NCs fluorescence light-up system through the use of the enhancer of G-rich overhang. Such a sensing system can be used to develop a DNA/Ag nanocluster-based beacon for the fluorescent detection of nucleic acid and thrombin with high selectivity and sensitivity, in which the detection sensitivity could be further enhanced through additional Exo III based amplification.
Co-reporter:Hui Wei and Erkang Wang
Chemical Society Reviews 2013 - vol. 42(Issue 14) pp:NaN6093-6093
Publication Date(Web):2013/06/05
DOI:10.1039/C3CS35486E
Over the past few decades, researchers have established artificial enzymes as highly stable and low-cost alternatives to natural enzymes in a wide range of applications. A variety of materials including cyclodextrins, metal complexes, porphyrins, polymers, dendrimers and biomolecules have been extensively explored to mimic the structures and functions of naturally occurring enzymes. Recently, some nanomaterials have been found to exhibit unexpected enzyme-like activities, and great advances have been made in this area due to the tremendous progress in nano-research and the unique characteristics of nanomaterials. To highlight the progress in the field of nanomaterial-based artificial enzymes (nanozymes), this review discusses various nanomaterials that have been explored to mimic different kinds of enzymes. We cover their kinetics, mechanisms and applications in numerous fields, from biosensing and immunoassays, to stem cell growth and pollutant removal. We also summarize several approaches to tune the activities of nanozymes. Finally, we make comparisons between nanozymes and other catalytic materials (other artificial enzymes, natural enzymes, organic catalysts and nanomaterial-based catalysts) and address the current challenges and future directions (302 references).
Co-reporter:Qingfeng Zhai, Siqi Zhang, Hong Jiang, Qin Wei, Erkang Wang and Jiahai Wang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 37) pp:NaN6377-6377
Publication Date(Web):2014/07/23
DOI:10.1039/C4TB00844H
In this article, we propose a new method for selective detection of Hg2+ based on a biomimetic nanopore sensing platform in combination with single-walled carbon nanotubes (SWNTs). As is well known, folded DNA in the presence of Hg2+ can be separated from single-stranded DNA through SWNTs, and the folded DNA can be quantitated with cone-shaped nanopore whose surface was coated by polyethyleneimine (PEI)/Zr4+. Both sensitivity and selectivity based on this paradigm can be guaranteed without immobilization of probes on the nanopore surface. This approach can warrant the detection limit for Hg2+ down to 8.3 nM (S/N = 3) with high selectivity against other metal ions. Moreover, the application of the sensor for lake water shows that the proposed method works well for real samples. This research demonstrates an alternative approach to detect targets of interest that holds high prospects for detecting other biomolecules or metal ions in the near future.
Co-reporter:Jiyang Liu, Shaojun Guo, Lei Han, Tianshu Wang, Wei Hong, Yaqing Liu and Erkang Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 38) pp:NaN20640-20640
Publication Date(Web):2012/08/16
DOI:10.1039/C2JM34494G
In this contribution, lipid monolayer membrane functionalized graphene sheets were prepared using a facile method. Interactions between the graphene and different types of liposomes, including charged and neutral, were also investigated. We found that the anionic liposomes could spontaneously self-organize into lipid monolayer membranes, partially covering the surface of graphene sheets. The resultant lipid monolayer functionalized graphene nanomaterials exhibited high stability in aqueous solution and an excellent performance as carrier for loading the anticancer drug, doxorubicin (DOX), with a high loading capacity of 70%. The loaded drug can be released under pH control. 10% and 14% of the bound DOX was released after 54 h at pH 10.0 and 7.0, respectively. Whereas, about 70% of DOX was released after 54 h at pH 5.0.
Co-reporter:Gaiping Li, Junfeng Zhai, Dan Li, Xiaona Fang, Hong Jiang, Qingzhe Dong and Erkang Wang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 41) pp:NaN9219-9219
Publication Date(Web):2010/09/13
DOI:10.1039/C0JM01776K
A facile one-pot method to prepare water-soluble, uniform-sized ZnS nanospheres (NSs) is reported. In the reaction, gradually decomposed thioacetamide (TAA) was used as the sulfur precursor, and cationic surfactant didodecyldimethylammonium bromide (DDAB) embedded with ferrocene (Fc) as the ligands for anions. The synthesized ZnS NSs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Wonderfully, the obtained ZnS NSs exhibited high performance in prohibiting the growth of Escherichia coli strain MG1655 (E. coli) and negligible mammalian cell toxicity, and these important features make it a promising antimicrobial agent for controlling implant-related infections.
Co-reporter:Wen Ren ; Shaojun Guo ; Shaojun Dong
The Journal of Physical Chemistry C () pp:
Publication Date(Web):May 5, 2011
DOI:10.1021/jp110532c
Herein we developed a simple and low-cost route for morphology-controllable synthesis of Ag dendrites based on a facile wet chemical route. The morphology of Ag dendrites was tunable by changing the concentration of capping reagent PVP. It was demonstrated that for higher concentrations of PVP, smaller Ag dendrites with shorter and smoother branches were obtained, while the ratio of the length of the branches to the body diameter of the Ag dendrites (L/D) became lower. It was also shown that the concentration of added AgNO3 was very important for the formation of Ag dendrites. The presented method is amenable for extension to large-scale synthesis of Ag dendrites. The prepared Ag dendrites exhibited strong near-infrared absorption proved by UV–visible spectra. Using p-ATP as a probe molecule, the SERS activity of prepared Ag dendrites was estimated. Based on the apparent enhancement factor and the measured diameter and L/D of the morphology-controlled Ag dendrites, the relation between the morphology and the SERS activity of Ag dendrites was investigated. It was shown that the smaller Ag dendrites with a lower L/D exhibited larger SERS activity.
![3-{[(2,3-dihydroxypropoxy)(hydroxy)phosphoryl]oxy}-2-(tetradecanoyloxy)propyl tetradecanoate](http://img.cochemist.com/ccimg/61400/61361-72-6.png)
![3-{[(2,3-dihydroxypropoxy)(hydroxy)phosphoryl]oxy}-2-(tetradecanoyloxy)propyl tetradecanoate](http://img.cochemist.com/ccimg/61400/61361-72-6_b.png)
![1-Thia-4,8-diazaspiro[4.5]decan-3-one,8-[3-(2-chloro-10H-phenothiazin-10-yl)propyl]-, hydrochloride (1:1)](http://img.cochemist.com/ccimg/27100/27007-85-8.png)
![1-Thia-4,8-diazaspiro[4.5]decan-3-one,8-[3-(2-chloro-10H-phenothiazin-10-yl)propyl]-, hydrochloride (1:1)](http://img.cochemist.com/ccimg/27100/27007-85-8_b.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8.png)
![Ferrate(2-), [7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-κN21,κN22,κN23,κN24]-, hydrogen (1:2), (SP-4-2)-](/data/chemimg/522800/14875-96-8_b.png)
![9-Octadecenoic acid(9Z)-, 1,1'-[1-[[[(2-aminoethoxy)hydroxyphosphinyl]oxy]methyl]-1,2-ethanediyl]ester](http://img.cochemist.com/ccimg/2500/2462-63-7.png)
![9-Octadecenoic acid(9Z)-, 1,1'-[1-[[[(2-aminoethoxy)hydroxyphosphinyl]oxy]methyl]-1,2-ethanediyl]ester](http://img.cochemist.com/ccimg/2500/2462-63-7_b.png)
![[1,1'-Biphenyl]-4,4'-diamine, 3,3',5,5'-tetramethyl-, sulfate (1:1)](http://img.cochemist.com/ccimg/54900/54827-18-8.png)
![[1,1'-Biphenyl]-4,4'-diamine, 3,3',5,5'-tetramethyl-, sulfate (1:1)](http://img.cochemist.com/ccimg/54900/54827-18-8_b.png)
![9-Octadecenoic acid(9Z)-,1,1'-[(1R)-1-[[[(2-aminoethoxy)hydroxyphosphinyl]oxy]methyl]-1,2-ethanediyl]ester](http://img.cochemist.com/ccimg/4100/4004-05-1.png)
![9-Octadecenoic acid(9Z)-,1,1'-[(1R)-1-[[[(2-aminoethoxy)hydroxyphosphinyl]oxy]methyl]-1,2-ethanediyl]ester](http://img.cochemist.com/ccimg/4100/4004-05-1_b.png)
![Sodium 2,3-dihydroxypropyl [(2r)-2,3-di(tetradecanoyloxy)propyl] Phosphate](http://img.cochemist.com/ccimg/200900/200880-40-6.png)
![Sodium 2,3-dihydroxypropyl [(2r)-2,3-di(tetradecanoyloxy)propyl] Phosphate](http://img.cochemist.com/ccimg/200900/200880-40-6_b.png)
![Propanoic acid,2-[4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy]-](http://img.cochemist.com/ccimg/157500/157435-10-4.png)
![Propanoic acid,2-[4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy]-](http://img.cochemist.com/ccimg/157500/157435-10-4_b.png)
![1-Propanaminium,N,N,N-trimethyl-2,3-bis[[(9Z)-1-oxo-9-octadecen-1-yl]oxy]-](http://img.cochemist.com/ccimg/113700/113669-21-9.png)
![1-Propanaminium,N,N,N-trimethyl-2,3-bis[[(9Z)-1-oxo-9-octadecen-1-yl]oxy]-](http://img.cochemist.com/ccimg/113700/113669-21-9_b.png)
![Sodium 3-((4'-amino-3,3',5,5'-tetramethyl-[1,1'-biphenyl]-4-yl)amino)propane-1-sulfonate](http://img.cochemist.com/ccimg/102100/102062-46-4.png)
![Sodium 3-((4'-amino-3,3',5,5'-tetramethyl-[1,1'-biphenyl]-4-yl)amino)propane-1-sulfonate](http://img.cochemist.com/ccimg/102100/102062-46-4_b.png)
![(6E)-6-[1-(2-quinolin-2-ylhydrazino)ethylidene]cyclohexa-2,4-dien-1-one](http://img.cochemist.com/ccimg/59100/59034-56-9.png)
![(6E)-6-[1-(2-quinolin-2-ylhydrazino)ethylidene]cyclohexa-2,4-dien-1-one](http://img.cochemist.com/ccimg/59100/59034-56-9_b.png)
![2,8-dibenzyl-1,3,7,9-tetrahydro-[1,3]benzoxazino[8,7-h][1,3]benzoxazine](http://img.cochemist.com/ccimg/41200/41193-15-1.png)
![2,8-dibenzyl-1,3,7,9-tetrahydro-[1,3]benzoxazino[8,7-h][1,3]benzoxazine](http://img.cochemist.com/ccimg/41200/41193-15-1_b.png)
![Ferrate(4-),[L-valyl-L-glutaminyl-L-lysyl-L-cysteinyl-L-alanyl-L-glutaminyl-L-cysteinyl-L-histidyl-kN-L-threonyl-L-valyl-L-glutamicacid cyclic (4®12'),(7®7')-bis(thioether) with7,12-bis(1-mercaptoethyl)-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(6-)-kN21,kN22,kN23,kN24]-,hydrogen (1:4)](http://img.cochemist.com/ccimg/31000/30975-71-4.png)
![Ferrate(4-),[L-valyl-L-glutaminyl-L-lysyl-L-cysteinyl-L-alanyl-L-glutaminyl-L-cysteinyl-L-histidyl-kN-L-threonyl-L-valyl-L-glutamicacid cyclic (4®12'),(7®7')-bis(thioether) with7,12-bis(1-mercaptoethyl)-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(6-)-kN21,kN22,kN23,kN24]-,hydrogen (1:4)](http://img.cochemist.com/ccimg/31000/30975-71-4_b.png)
![4-{[2-(2-oxo-2H-indol-3-yl)hydrazino]sulfonyl}benzoic acid](http://img.cochemist.com/ccimg/29600/29519-87-7.png)
![4-{[2-(2-oxo-2H-indol-3-yl)hydrazino]sulfonyl}benzoic acid](http://img.cochemist.com/ccimg/29600/29519-87-7_b.png)
![2(1H)-Pyrimidinone,4-amino-1-[5-O-(tricyclo[3.3.1.13,7]dec-1-ylcarbonyl)-b-D-arabinofuranosyl]-](http://img.cochemist.com/ccimg/23200/23113-01-1.png)
![2(1H)-Pyrimidinone,4-amino-1-[5-O-(tricyclo[3.3.1.13,7]dec-1-ylcarbonyl)-b-D-arabinofuranosyl]-](http://img.cochemist.com/ccimg/23200/23113-01-1_b.png)
![21-[6-(methylsulfanyl)-9H-purin-9-yl]pregn-4-ene-3,20-dione](http://img.cochemist.com/ccimg/21200/21170-27-4.png)
![21-[6-(methylsulfanyl)-9H-purin-9-yl]pregn-4-ene-3,20-dione](http://img.cochemist.com/ccimg/21200/21170-27-4_b.png)
![Methanaminium,N-[4-[[4-(dimethylamino)phenyl]phenylmethylene]-2,5-cyclohexadien-1-ylidene]-N-methyl-](http://img.cochemist.com/ccimg/10400/10309-95-2.png)
![Methanaminium,N-[4-[[4-(dimethylamino)phenyl]phenylmethylene]-2,5-cyclohexadien-1-ylidene]-N-methyl-](http://img.cochemist.com/ccimg/10400/10309-95-2_b.png)
![Cyclohexanamine,N-[(2-benzothiazolylthio)methyl]-N-cyclohexyl-](http://img.cochemist.com/ccimg/6400/6323-43-9.png)
![Cyclohexanamine,N-[(2-benzothiazolylthio)methyl]-N-cyclohexyl-](http://img.cochemist.com/ccimg/6400/6323-43-9_b.png)
![(5E)-5-[(4-methylphenyl)hydrazono]-6-oxo-5,6-dihydronaphthalene-2-sulfonic acid](http://img.cochemist.com/ccimg/5900/5859-07-4.png)
![(5E)-5-[(4-methylphenyl)hydrazono]-6-oxo-5,6-dihydronaphthalene-2-sulfonic acid](http://img.cochemist.com/ccimg/5900/5859-07-4_b.png)
![1-(naphthalen-2-yl)-2-[(6-nitro-1,3-benzothiazol-2-yl)sulfanyl]ethanone](http://img.cochemist.com/ccimg/5400/5397-96-6.png)
![1-(naphthalen-2-yl)-2-[(6-nitro-1,3-benzothiazol-2-yl)sulfanyl]ethanone](http://img.cochemist.com/ccimg/5400/5397-96-6_b.png)
![8-[3-(2-chlorophenothiazin-10-yl)propyl]-1-thia-4,8-diazaspiro[4.5]decan-3-one](http://img.cochemist.com/ccimg/24600/24527-27-3.png)
![8-[3-(2-chlorophenothiazin-10-yl)propyl]-1-thia-4,8-diazaspiro[4.5]decan-3-one](http://img.cochemist.com/ccimg/24600/24527-27-3_b.png)
![4-tert-butyl-2-[(cyclohexylamino)methyl]-6-methylphenol](http://img.cochemist.com/ccimg/6700/6640-90-0.png)
![4-tert-butyl-2-[(cyclohexylamino)methyl]-6-methylphenol](http://img.cochemist.com/ccimg/6700/6640-90-0_b.png)
](http://img.cochemist.com/ccimg/27000/26913-06-4.png)
](http://img.cochemist.com/ccimg/27000/26913-06-4_b.png)
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![L-Phenylalanine,N-[[(3R)-5-chloro-3,4-dihydro-8-hydroxy-3-methyl-1-oxo-1H-2-benzopyran-7-yl]carbonyl]-](http://img.cochemist.com/ccimg/400/303-47-9.png)
![L-Phenylalanine,N-[[(3R)-5-chloro-3,4-dihydro-8-hydroxy-3-methyl-1-oxo-1H-2-benzopyran-7-yl]carbonyl]-](http://img.cochemist.com/ccimg/400/303-47-9_b.png)
