Co-reporter:Cui Ye, Min Qiang Wang, Hong Qun Luo, and Nian Bing Li
Analytical Chemistry November 7, 2017 Volume 89(Issue 21) pp:11697-11697
Publication Date(Web):October 11, 2017
DOI:10.1021/acs.analchem.7b03150
MicroRNA (miRNAs) quantification, especially at low abundance, is vital for disease diagnosis, prognosis, and therapy. Herein we develop a distinctive label-free “off–on” configuration for photoelectrochemical (PEC) sensing platform fabrication, coupled with DNA four-way junction (4J) architecture as well as G-wire superstructure for signal amplification. In addition, ultrathin copper phosphate nanosheets (CuPi NSs) coating Au nanoparticles (Au-CuPi NSs) serve as a highly efficient photocathode substrate. To improve the sensitivity, and avoid the false positive signals, the quencher, gold nanoparticles (GNPs), is utilized to switch off the PEC signal because of the commendable surface plasmon resonance (SPR) absorption. Subsequently, ingenious DNA 4J architecture is applied to export proportional c-myc regions for target quantification. Assisted with the G-wire superstructure formation, the enhancer 5,10,15,20-tetra(4-sulfophenyl)-21H,23H-porphyrin (TSPP) is coupled on the substrate to switch on the PEC signal, thus realizing the miRNA assay with persuasive accuracy, high sensitivity, and low detection limit. In addition, we execute the miRNA detection in prostate carcinoma cell line 22Rv1, and acquire desirable quantitative capability. Remarkably, the prepared PEC sensing platform not only realizes the highly efficient miRNAs quantification, but also uncovers a marvelous horizon for sensing platform fabrication.
Co-reporter:Na Li, Ting Liu, Shi Gang Liu, Shu Min Lin, Yu Zhu Fan, Hong Qun Luo, Nian Bing Li
Sensors and Actuators B: Chemical 2017 Volume 248(Volume 248) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.snb.2017.03.068
•Visible and fluorescent detection is developed for melamine detection in raw milk.•One-step melamine detection is label free and rapid without tedious operation.•Silver nanoparticles are synthesized using carbon dots as reductant and stabilizer.•The strategy shows high sensitivity and selectivity for detection of melamine.Using carbon dots as the reductant and stabilizer, a visible and fluorescent method was developed for melamine detection in raw milk with one-step synthesized silver nanoparticles. In this work, carbon dots (C-dots) were applied to reduce silver ions and stabilize the nanoparticles, resulting in the formation of silver nanoparticles (AgNPs). As a result, the inherent fluorescence emission of C-dots was significantly reduced after the formation of AgNPs. However, in the presence of melamine, silver ions could interact with the nitrogen atoms in amine and triazine groups of melamine. With 0–2 μM melamine, aggregated AgNPs were found after the reduction by C-dots, resulting in color and absorbance changes. With further increase of melamine (2–20 μM), both formation and aggregation of AgNPs were inhibited, and the fluorescence was gradually increased. This optical platform was optimized for melamine detection and then was applied to detecting melamine in raw milk samples. The results for melamine assay based on visible and fluorescent method showed the requisite sensitivity with a low detection limit of 30 nM, as well as high selectivity.Download high-res image (184KB)Download full-size image
Co-reporter:Na Li, Shi Gang Liu, Yu Die Zhu, Ting Liu, Shu Min Lin, Yan Shi, Hong Qun Luo, Nian Bing Li
Sensors and Actuators B: Chemical 2017 Volume 251(Volume 251) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.snb.2017.05.071
•DNA and carbon dots were employed to co-mediate the growth of AuNPs.•The properties of grown AuNPs are explored in this work.•Visual detection is developed for nucleic acids and proteins detection.•The results for biomolecule assays show requisite sensitivity and selectivity.DNA and carbon dots were utilized to co-mediate the growth of gold nanoparticles (AuNPs). The properties of grown AuNPs were discussed and applied to colorimetric biomolecule determination. When target biomolecules were absent, single-stranded oligonucleotides (ssDNA) were adsorbed on the surface of AuNP seeds. Branched AuNP solution of blue color was obtained after carbon dots reduction. In the presence of target DNA, it hybridized with the ssDNA and double-stranded oligonucleotides (dsDNA) were formed. As a result, a spherical AuNP solution of red color was achieved after growth as dsDNA would not be adsorbed by AuNP seeds. A similar situation was observed with thrombin. The complex of thrombin and its aptamer was formed, giving rise to spherical AuNPs after growth. The target biomolecule determination was realized by virtue of color change, consistent with the peak shift in UV–vis absorption spectrum. The detection limits were determined to be 5 nM for target DNA and 1.8 nM for thrombin, respectively. The biomolecule sensors showed the requisite selectivity against possible interferents, and the assay for target DNA exhibited the potential for distinguishing single-base mismatch. These results served as the basis for constructing future biomolecule sensors using DNA and carbon dots co-mediated growth of AuNPs.Download high-res image (149KB)Download full-size image
Co-reporter:Hao Lin Zou, Bang Lin Li, Hong Qun Luo, Nian Bing Li
Sensors and Actuators B: Chemical 2017 Volume 253(Volume 253) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.snb.2017.06.158
•0D-2D heterostructures of Au nanoparticles and layered MoS2 were obtained.•The properties of layered MoS2 were enhanced with the decoration of Au nanoparticles.•Heterostructures with high conductivity and large active surface contribute to novel sensors.•DA, AA, UA, and nitrite can be simultaneously detected with high selectivity.Recently, hybrids of layered MoS2 are highly encouraged to handle the puzzles, taken by the weakness of two-dimensional (2D) transition metal dichalcogenides (TMDC), including low conductivity and lack of active edge sites. Considering the merits of zero-dimensional (0D) nanomaterials, the emerging heterostructures based on 0D Au nanoparticles and 2D MoS2nanosheets (MoS2-NSs) are successfully obtained via a spontaneously reduced process with the addition of HAuCl4 in exfoliated MoS2-NSs aqueous dispersions. Significantly, with the combination of high conductivity rate and large active surface, the synthetic effect results in a diversity of improved properties of 0D-2D heterostructures, not only exhibiting improved stability, but also remarkably enhancing the selectivity and sensitivity for electrochemically simultaneous detections of dopamine, ascorbic acid, uric acid, and nitrite. Our current achievements of 0D-2D heterostructures contribute fresh ideas to the overall development of more advanced future TMDC based sensors.Download high-res image (96KB)Download full-size image
Co-reporter:Shuo Geng, Shu Min Lin, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2017 Volume 253(Volume 253) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.snb.2017.06.118
•PEG@ZnO QDs dispersed well in water with yellow fluorescence were synthesized.•PEG@ZnO QDs fluorescence can be quenched by Cu2+ ion because of the aggregation.•A novel method based on the QDs for detection of Cu2+ ion was proposed.•This method is simple, environment-friendly, low-cost, and rapid.As an important heavy metal ion, copper has the negative influence on otherwise healthy individuals, so establishing a valid way for the highly efficient, sensitive, and quantitative determination of Cu2+ ion becomes an emergency in the environmental analysis. In the present work, water-soluble luminescent ZnO quantum dots (QDs) capped by polyethylene glycol (PEG) have been synthesized by a simple solution method. The PEG capped ZnO QDs (PEG@ZnO QDs) showed yellow fluorescence. High-resolution transmission electron microscopy, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, and luminescence spectroscopy were applied to elucidate the properties of the PEG@ZnO QDs. In addition, the yellow fluorescence of the PEG@ZnO QDs was quenched when Cu2+ ion was added to the PEG@ZnO QDs solutions. Therefore, a novel fluorescent probe was designed to detect Cu2+ in water solution. The linear relationships were 10–200 nM and 2–10 μM, respectively, with the detection limit for Cu2+ at 3.33 nM according to 3σ/slope (where σ denotes the standard deviation of the blank measures). The proposed sensor of the PEG@ZnO QDs has also been used in natural water samples to examine the availability of this method. In addition, the quenching mechanism was discussed, which may be attributed to the aggregation induced quenching.Download high-res image (70KB)Download full-size image
Co-reporter:Xiao Fang Zhang, Na Li, Cui Ye, Jia Yu Liang, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2017 Volume 250(Volume 250) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.snb.2017.04.178
•RRS strategy was employed to detect active UDG for the first time.•G-wire nanostructure with special RRS characteristics was utilized in this study.•Full use of the ssDNA from unwound dsDNA and dual amplification was achieved.•Label-free RRS DNA machine showed satisfactory selectivity and applicability.Uracil-DNA glycosylase (UDG), one of the base-excision repair enzymes, is closely relevant for the diseases of the organism. Here, we proposed a resonance Rayleigh scattering (RRS) strategy for sensitively detecting the active UDG based on a dual amplification DNA machine without label under the catalysis of exonuclease III (Exo III). In our study, a double-stranded DNA complex S1-S2 containing triggers and peculiar uracil bases was employed. To achieve the dual amplification strategy, we adopted hairpin probes HP1 and HP2. The unique hairpin probes can partially hybridize with S1 and S2, respectively. With the excision reaction of UDG, the uracil bases were excised from S2 in double-stranded S1-S2, resulting in a lower melting temperature of the S1-S2. Then, the S1-S2 was dissociated to single-stranded S1 and S2 with abasic sites. Subsequently, the liberated strands separately hybridized with hairpins to initiate the Exo III-catalyzed dual amplification. In the presence of K+, countless c-myc sequences which were produced by the amplification reaction formed G-quadruplex structures. Finally, with the addition of Mg2+, long and continuous G-wire structures were obtained, causing an obvious enhancement of RRS intensity. The proposed RRS DNA machine obtained the limit of detection as low as 1.0 × 10−5 U/mL for the active UDG assay. Moreover, qualitative analysis of the active UDG was successfully achieved in HeLa cells lysate. The DNA machine is a potential tool to be used in UDG clinical diagnosis or functional study.Download high-res image (95KB)Download full-size image
Co-reporter:Liu Li Liao, Shi Mo, Hong Qun Luo, Nian Bing Li
Journal of Colloid and Interface Science 2017 Volume 499(Volume 499) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.jcis.2017.03.091
Longan seed and peel were extracted and used for impeding the corrosion of mild steel in hydrochloric acid solution. Experimental analyses indicate that the water extract of Longan’s seed and peel, a mixed type inhibitor, can be chemically adsorbed onto the steel surface, and its inhibition effect rises with increasing extract concentration. To understand the adsorption mechanism and the contributions of the four main compounds of the extract to corrosion protection effect, quantum chemical methods and infrared spectrum were also employed. Theoretically, four main antioxidant compounds were regarded as effective components in the water extract of Longan’s seed and peel.The extract of Longan’s peel and seed inhibits the corrosion of mild steel by adsorbing the effective compounds on the steel surface, resulting in the increased impedance values in Nyquist curves.Download high-res image (86KB)Download full-size image
Co-reporter:Ting Wen, Fei Qu, Nian Bing Li, Hong Qun Luo
Arabian Journal of Chemistry 2017 Volume 10, Supplement 2(Volume 10, Supplement 2) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.arabjc.2013.06.013
In this work, we developed a facile, sensitive, and rapid spectrophotometric method for copper(II) ion detection in aqueous media using polyethyleneimine. Polyethyleneimine is a cationic polymer that has no absorption in the wavelength range of 250–800 nm. When trace amounts of copper(II) ion was added to the colorless polyethyleneimine solution, copper(II) ion could react with the amino groups of the polyethyleneimine to form a dark blue cuprammonium complex whose absorption spectrum exhibited two absorption peaks at 275 and 630 nm, respectively. The effects of parameters such as polyethyleneimine concentration, pH, temperature, reaction time, and the most suitable medium for the reaction were investigated. A linear relationship (R2 = 0.9997) between absorbance and the concentration of copper(II) ion was found at the maximum absorption peak of 275 nm in the concentration range of 2–400 μM. The detection limit for copper(II) ion was 566 nM. The response of polyethyleneimine toward different metal ions was investigated, and polyethyleneimine displayed a high selectivity for the copper(II) ion among the metal ions examined. This biocompatible and sensitive sensor may find applications in copper(II) ion detection in environmental and biological processes.
Co-reporter:Na Li;Yu Die Zhu;Ting Liu;Shi Gang Liu;Shu Min Lin;Yan Shi;Nian Bing Li
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 5) pp:1993-1996
Publication Date(Web):2017/02/28
DOI:10.1039/C6NJ03491H
The turn-on fluorescence of pyrophosphate anion (PPi) was detected using DNA-attached cobalt oxyhydroxide. The fluorescence signal was quenched when carboxyfluorescein-labeled ssDNA was adsorbed by CoOOH nanoflakes through electrostatic interaction. With the addition of target PPi, PPi competed with DNA for CoOOH nanoflakes, resulting in turn-on fluorescence.
Co-reporter:Cui Ye;Min Qiang Wang;Ling Jie Li;Nian Bing Li
Nanoscale (2009-Present) 2017 vol. 9(Issue 22) pp:7526-7532
Publication Date(Web):2017/06/08
DOI:10.1039/C7NR02037F
Herein, we focus on preparing a highly efficient photocatalytic material to construct a signal-on photoelectrochemical (PEC) sensing platform in view of the rigorous demand of accurate miRNA quantification. The well-dispersed Pt nanoclusters-coated copper phosphate ultrathin nanosheets (PtNCs/Cu3(PO4)2NSs) were first successfully synthesized as a photoelectrode material. Because of the ultrathin two-dimensional lamellar structure of Cu3(PO4)2NSs with a 1.3 nm thickness, as well as the homogeneous size and abundant PtNCs loaded on Cu3(PO4)2NSs, the resultant PtNCs/Cu3(PO4)2NSs were employed as a photoelectrode material for the first time and revealed outstanding photocatalytic activity in PEC sensing as a substrate. As a well-designed protocol, we realized accurate miRNA quantification via a novel signal amplification strategy based on G-wire superstructure exponentially ligating a signal probe, which possesses efficient and simple operation compared to the traditional amplification method. Moreover, the electron donor is generated in situ by lactate oxidase (Lox) labels catalyzing lactate for H2O2 production, boosting the efficient separation of electron–hole pairs for further signal amplification. Impressively, this PEC sensing platform is commendably utilized to determine miRNA-141 from prostate carcinoma cell line 22Rv1. This study, considering the excellent PtNCs/Cu3(PO4)2NSs combined with G-wire superstructure for exponential signal amplification strategy, paves a new path in biosensing and clinical diagnosis.
Co-reporter:Jiang Xue Dong;Zi Li Wang;Yue Yang;Zhong Feng Gao;Bang Lin Li;Hui Hui Jiang;Nian Bing Li
Journal of Materials Chemistry B 2017 vol. 5(Issue 4) pp:707-713
Publication Date(Web):2017/01/25
DOI:10.1039/C6TB02449A
Developing probes with good biocompatibility and realizing intracellular detection in living cells are of great significance for biomedicine and life sciences, but remain a challenge presently. In this paper, we describe a rapid and highly selective biosensor for Fe3+ detection in living cells based on the Maillard reaction fluorescent products (MRFPs) of glutathione and ascorbic acid as a probe. Experiments show that the MRFPs are non-cytotoxic and possess excellent biocompatibility. Moreover, the MRFPs show a rapid response and good selectivity towards Fe3+ over other metal ions under physiological pH conditions in vitro. The introduction of Fe3+ can quench the fluorescence of MRFPs, and the fluorescence intensity of system decreases linearly with the increasing concentration of Fe3+ in the range of 0.05–50 μM with the detection limit of 4.6 nM at a signal-to-noise ratio of 3. Moreover, the recognition mechanism has been discussed, which is attributed to the charge transfer from excited-state MRFPs molecules to metal ions. In addition, the MRFPs have been successfully demonstrated to be a good imaging probe for Fe3+ sensing in living cells. This study shows that the biocompatible MRFPs might hold great potential for applications in bioimaging, diagnosis, and therapy of intracellular diseases.
Co-reporter:Lei Han;Shi Gang Liu;Jiang Xue Dong;Jia Yu Liang;Ling Jie Li;Nian Bing Li
Journal of Materials Chemistry C 2017 vol. 5(Issue 41) pp:10785-10793
Publication Date(Web):2017/10/26
DOI:10.1039/C7TC03314A
The facile and effective synthesis of truly multicolor photoluminescent (PL) polymer carbon dots (PCDs) is still a considerable challenge. Here, a mild and facile synthetic method to prepare multicolor emissive PCDs by self-oxidation and autopolymerization using hydroquinone and ethylenediamine as precursors is reported. The resulting PCDs were separated via silica-gel column chromatography, which gave three types of PCDs emitting bright and stable yellow, green, and blue fluorescence. The three types of PCDs exhibited attractive features such as excellent solubility, excitation wavelength-independent photoluminescence, high stability, monoexponential fluorescence lifetimes, and homogeneous optical properties. The uniform optical properties of the as-prepared PCDs helped us to explore their multicolor emissive PL mechanism. Detailed characterization and investigation of the PCDs revealed that their surface state was primarily responsible for the observed multicolor emissive photoluminescence. A PL mechanism that involved control of the energy gap by the surface state was proposed to explain the effect of the surface functional groups on the PL properties of the PCDs. The emission of the PCDs was strongly associated with the CN functional groups on their surface. The band gap narrowed with increasing content of CN on the PCD surface, resulting in the red shift of the PL emission peak.
Co-reporter:Shi Mo, Hong Qun Luo, Nian Bing Li
Journal of Colloid and Interface Science 2017 Volume 505(Volume 505) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jcis.2017.06.075
Green corrosion inhibitors are of great benefit to the protection of pipes or tanks in seawater systems. The properties of the corrosion inhibitor such as toxicity and anticorrosion performance are closely related to its molecular structure. Some thiazole derivatives are commonly known as food flavors. The influences of two thiazole flavor ingredients on Cu corrosion in NaCl solution were analyzed in this study, namely, 4-methyl-5-vinylthiazole (MVT) and 5-(2-hydroxyethyl)-4-methylthiazole (HMT). Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were employed to evaluate their anti-corrosion abilities. Theoretical calculations were conducted to investigate their possible adsorption modes. The thiazole ring endows the two compounds with the high inhibition performace. However, with a conjugated system, the ethenyl has a more pronounced contribution to electron donation and adsorption ability on the Cu surface than hydroxyethyl group.Download high-res image (90KB)Download full-size image
Co-reporter:Wei Tao Huang, Ling Xiao Chen, Jing Lei Lei, Hong Qun Luo, Nian Bing Li
Sensors and Actuators B: Chemical 2017 Volume 239() pp:704-710
Publication Date(Web):February 2017
DOI:10.1016/j.snb.2016.08.056
•Molecules could be used as universal artificial neurons for sensing analytes.•Our approach allows us to utilize simple sensing molecules as McCulloch-Pitts neuron.•Molecular neuron can execute logic computation, information encoding, and encryption.The impressive functions of brain circuits have inspired many scientists to attempt in designing neuron analogues by using artificial molecular systems or electronic devices. However, the study of molecular neuron has not produced an equal variety of models. Here, using UV–vis absorption, fluorescence, and resonance light scattering spectroscopies for pH sensing with a common indicator—Congo red dye, we show how Congo red molecules can be used to construct molecular neuron and exhibit neuron-like behavior. Our molecular neural model uses molecular groups as ‘dendrites’ which receive and sense environmental stimuli inputs (pH), molecular matrix as ‘soma’ which acts as the summation function, and the change in optical characteristics as ‘axon’ which represents outputs. Our approach allows us to utilize simple sensing molecules as McCulloch-Pitts neuron for experimental implementation of large-scale logic computation in batch mode and to use extraordinary information density inherent in molecular neuron for alphanumeric information encoding and molecular cryptography. Our results suggest that molecules could be used as universal artificial neurons with the capability of sensing analytes or environmental stimuli, remembering patterns of molecular events, and making decisions.
Co-reporter:Shi Gang Liu, Na Li, Yu Zhu Fan, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2017 Volume 243() pp:634-641
Publication Date(Web):May 2017
DOI:10.1016/j.snb.2016.12.038
•Fluorescent polymer nanoparticles (PNPs) were formed by polyethyleneimine and HCHO.•The fluorescence of PNPs was selectively and sensitively quenched by Cu2+.•The intrinsically fluorescent PNPs were used as a probe for sensing Cu2+.•Cysteine restored the fluorescence because it removed Cu2+ from the surface of PNPs.•An IMPLICATION molecular logic gate was designed based on the PNPs/Cu2+/Cys system.We have demonstrated a fluorescence approach for rapid, environment-friendly, and selective detection of Cu2+ in aqueous media using a kind of easily prepared and autofluorescent polymer nanoparticles (PNPs) as a sensor. The PNPs were synthesized by crosslinking hyperbranched polyethyleneimine (hPEI) with formaldehyde in water solution, and they emitted strong intrinsic fluorescence without the conjugation to any external fluorescent agent. The Cu2+ assay was on the basis of the principle that Cu2+ can be adsorbed on the surface of the PNPs, resulting in the fast and remarkable fluorescence quenching through electron transfer. The developed sensor was applied to the analysis of copper ions in environmental water samples with satisfactory results. Furthermore, the fluorescence of the PNPs-Cu2+ system can restore upon addition of cysteine (Cys) because of its ability to remove Cu2+ from the surface of PNPs. Based on the fluorescence “on-off-on” conversion, a reversible IMPLICATION logic gate was designed by using Cu2+ and Cys as the two inputs, and fluorescence intensity of the PNPs as the output signal.
Co-reporter:Jiang Xue Dong, Zhong Feng Gao, Ying Zhang, Bang Lin Li, Wei Zhang, Jing Lei Lei, Nian Bing Li and Hong Qun Luo
NPG Asia Materials 2016 8(12) pp:e335
Publication Date(Web):2016-12-01
DOI:10.1038/am.2016.184
Water-soluble fluorescent Ag nanoclusters (Ag NCs) with distinct pH-switchable agglomeration and spectral signal responses are prepared using a facile etching method. Increased and decreased pH cause the Ag NCs to switch between agglomeration and dispersion, accompanied by decreases in and recoveries of fluorescence intensity and absorbance. The pH switchable behavior of the Ag NCs is attributed to carboxyl groups on the nanocluster surface that are rich in the citrate and amido functional groups of ligands (glutathione), creating an easily formed, weak molecular interaction among Ag NCs (for example, hydrogen bonding) and maintaining a balance in the colloidal solution, whereas a change in pH will disrupt the balance, leading to the reversible agglomeration of Ag NCs and the switchable spectral signal response. In addition, because urea and glucose can change the pH of a solution by producing NH3 and gluconic acid in enzyme-catalyzed reactions, the pH-switchable behavior of the Ag NCs is used to develop them as an optical probe to establish a regenerated biosensing platform for the sensitive and selective detection of urea and glucose, and the test results are satisfactory.
Co-reporter:Shi Gang Liu, Dan Luo, Na Li, Wei Zhang, Jing Lei Lei, Nian Bing Li, and Hong Qun Luo
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 33) pp:21700
Publication Date(Web):July 29, 2016
DOI:10.1021/acsami.6b07407
Water-soluble nonconjugated polymer nanoparticles (PNPs) with strong fluorescence emission were prepared from hyperbranched poly(ethylenimine) (PEI) and d-glucose via Schiff base reaction and self-assembly in aqueous phase. Preparation of the PEI–d-glucose (PEI-G) PNPs was facile (one-pot reaction) and environmentally friendly under mild conditions. Also, PEI-G PNPs showed a high fluorescence quantum yield in aqueous solution, and the fluorescence properties (such as concentration- and solvent-dependent fluorescence) and origin of intrinsic fluorescence were investigated and discussed. PEI-G PNPs were then used to develop a fluorescent probe for fast, selective, and sensitive detection of nitro-explosive picric acid (PA) in aqueous medium, because the fluorescence can be easily quenched by PA whereas other nitro-explosives and structurally similar compounds only caused negligible quenching. A wide linear range (0.05–70 μM) and a low detection limit (26 nM) were obtained. The fluorescence quenching mechanism was carefully explored, and it was due to a combined effect of electron transfer, resonance energy transfer, and inner filter effect between PA and PEI-G PNPs, which resulted in good selectivity and sensitivity for PA. Finally, the developed sensor was successfully applied to detection of PA in environmental water samples.Keywords: fluorescent sensor; intrinsic fluorescence; nonconjugated polymer nanoparticles; picric acid; poly(ethylenimine)
Co-reporter:Wang Ren, Ying Zhang, Hong Guo Chen, Zhong Feng Gao, Nian Bing Li, and Hong Qun Luo
Analytical Chemistry 2016 Volume 88(Issue 2) pp:1385
Publication Date(Web):December 24, 2015
DOI:10.1021/acs.analchem.5b03972
A novel signal-on and label-free resonance Rayleigh scattering (RRS) aptasensor was constructed for detection of Hg2+ based on Hg2+-triggered Exonuclease III-assisted target recycling and growth of G-quadruplex nanowires (G-wires) for signal amplification. The hairpin DNA (H-DNA) was wisely designed with thymine-rich recognition termini and a G-quadruplex sequence in the loop and employed as a signal probe for specially recognizing trace Hg2+ by a stable T–Hg2+–T structure, which automatically triggered Exonuclease III (Exo-III) digestion to recycle Hg2+ and liberate the G-quadruplex sequence. The free G-quadruplex sequences were self-assembled into guanine nanowire (G-wire) superstructure in the presence of Mg2+ and demonstrated by gel electrophoresis. The RRS intensity was dramatically amplified by the resultant G-wires, and the maximum RRS signal at 370 nm was linear with the logarithm of Hg2+ concentration in the range of 50.0 pM to 500.0 nM (R = 0.9957). Selectivity experiments revealed that the as-prepared RRS sensor was specific for Hg2+, even coexisting with high concentrations of other metal ions. This optical aptasensor was successfully applied to identify Hg2+ in laboratory tap water and river water samples. With excellent sensitivity and selectivity, the proposed RRS aptasensor was potentially suitable for not only routine detection of Hg2+ in environmental monitoring but also various target detection just by changing the recognition sequence of the H-DNA probe.
Co-reporter:Jing Jia, Hong Guo Chen, Ji Feng, Jing Lei Lei, Hong Qun Luo, Nian Bing Li
Analytica Chimica Acta 2016 Volume 908() pp:95-101
Publication Date(Web):18 February 2016
DOI:10.1016/j.aca.2015.12.028
•The dual-signaling ratiometric method improved the precision and sensitivity.•The fabrication of biosensor is less time-consuming and simpler.•The biosensor shows excellent selectivity and repeatability.•This biosensor can be easily regenerated by using l-cysteine.Inspired by dual-signaling ratiometric mechanism which could reduce the influence of the environmental change, a novel, convenient, and reliable method for the detection of mercury ions (Hg2+) based on Y-shaped DNA (Y-DNA) was developed. Firstly, the Y-DNA was formed via the simple annealing way of using two different redox probes simultaneously, omitting the multiple operation steps on the electrode. The Y-DNA was immobilized on the gold electrode surface and then an obvious ferrocene (Fc) signal and a weak methylene blue (MB) signal were observed. Upon addition of Hg2+, the Y-DNA structure was transformed to hairpin structure based on the formation of T-Hg2+-T complex. During the transformation, the redox MB gets close to and the redox Fc gets far away from the electrode surface, respectively. This special design allows a reliable Hg2+ detection with a detection range from 1 nM to 5 μM and a low detection limit down to 0.094 nM. Furthermore, this biosensor exhibits good selectivity and repeatability, and can be easily regenerated by using l-cysteine. This study offers a simple and effective method for designing ratiometric biosensors for detecting other ions and biomolecules.
Co-reporter:Jian Rong Zhang, Yuan Yuan Yue, Hong Qun Luo and Nian Bing Li
Analyst 2016 vol. 141(Issue 3) pp:1091-1097
Publication Date(Web):30 Nov 2015
DOI:10.1039/C5AN02251G
Picric acid (PA) explosive is a hazard to public safety and health, so the sensitive and selective detection of PA is very important. In the present work, polyethyleneimine stabilized Ag nanoclusters were successfully used for the sensitive and selective quantification of PA on the basis of fluorescence quenching. The quenching efficiency of Ag nanoclusters is proportional to the concentration of PA and the logarithm of PA concentration over two different concentration ranges (1.0 nM–1 μM for the former and 0.25–20 μM for the latter), thus the proposed quantitative strategy for PA provides a wide linear range of 1.0 nM–20 μM. The detection limit based on 3σ/K is 0.1 nM. The quenching mechanism of Ag nanoclusters by PA is discussed in detail. The results indicate that the selective detection of PA over other nitroaromatics including 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), p-nitrotoluene (p-NT), m-dinitrobenzene (m-DNB), and nitrobenzene (NB), is due to the electron transfer and energy transfer between PA and polyethyleneimine-capped Ag nanoclusters. In addition, the experimental data obtained for the analysis of artificial samples show that the proposed PA sensor is potentially applicable in the determination of trace PA explosive in real samples.
Co-reporter:Zhi Cheng, Shi Mo, Jing Jia, Ji Feng, Hong Qun Luo and Nian Bing Li
RSC Advances 2016 vol. 6(Issue 18) pp:15210-15219
Publication Date(Web):29 Jan 2016
DOI:10.1039/C5RA20246A
The inhibition effect of 4,6-diamino-2-mercaptopyrimidine (DAMP) as a copper corrosion inhibitor in 3.5 wt% NaCl solution was investigated by weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization. The inhibition efficiency increased with increasing DAMP concentration in the range of 1.0 to 2.0 mM DAMP and decreased with increasing temperature. The obtained results showed that DAMP inhibited both the anodic and cathodic currents and the maximum inhibition efficiency reached 93.2% at 2.0 mM DAMP. The inhibition performance of DAMP was confirmed by SEM and EDS. Quantum chemical calculations revealed that the DAMP molecule was adsorbed on the copper surface in a paralleled way through S and N atoms and the pyrimidine ring. Adsorption of DAMP was found to obey the Langmuir adsorption isotherm.
Co-reporter:Jiang Xue Dong, Xiao Fang Song, Yan Shi, Zhong Feng Gao, Bang Lin Li, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics 2016 81() pp: 473-479
Publication Date(Web):15 July 2016
DOI:10.1016/j.bios.2016.03.017
•The Maillard reaction of glutathione and ascorbic acid was performed.•A water-soluble and blue-emitting fluorescent product was obtained.•The fluorescent product possesses excellent stability and high quantum yield.•The product was used as a probe for detecting Hg2+ and biothiols.Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg2+ and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg2+-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg2+, cysteine, homocysteine, and glutathione are 0.05–12, 0.5–10, 0.3–20, and 0.3–20 μM, respectively. The detection limits for Hg2+, cysteine, homocysteine, and glutathione are 22, 47, 96, and 30 nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg2+ and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results.
Co-reporter:Shuo Geng, Shu Min Lin, Shi Gang Liu, Wei Zhang, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2016 Volume 236() pp:591-596
Publication Date(Web):29 November 2016
DOI:10.1016/j.snb.2016.06.043
•PEI capped ZnO QDs dispersed well in ethanol with high fluorescence was synthesized.•The PEI capped ZnO QDs fluorescence was quenched with increasing water content.•The PEI capped ZnO QDs were aggregated in water because of the high surface energy.•A novel method based on the QDs for detection of alcoholic strength was proposed.•This method is simple, environment-friendly, low-cost, and rapid.We synthesized polyethyleneimine capped ZnO quantum dots (PEI-ZnO QDs) which dispersed well in ethanol by using a two-step method. UV–visible absorption spectroscopy, photoluminescence, Fourier transform infrared spectroscopy, high resolution transmission electron microscope, and field emission scanning electron microscope were used to characterize the as-prepared PEI-ZnO QDs. It emitted green-yellow fluorescence (527 nm) for excitation at 355 nm. We used the PEI-ZnO QDs to determine the alcoholic strength because of its different property in water and ethanol which caused decrease in the PEI-ZnO QDs fluorescence intensity with increasing water content. With this method, we determined the alcoholic strength of different artificial samples with a linear range from 20% to 60% vol and detected commercial spirits with satisfactory results.
Co-reporter:Yu Ling, Ling Xiao Chen, Jiang Xue Dong, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2016 Volume 156() pp:22-27
Publication Date(Web):5 March 2016
DOI:10.1016/j.saa.2015.11.019
•A novel RRS sensor for Al(III) was established with hemin-functionalized graphene.•It is a simple, rapid assay for Al(III) detection and the reaction only needs 2 min.•This method has been successfully used for Al(III) detection in real samples.•The principle of this sensor has been discussed in detail.A novel method for direct determination of Al(III) by using hemin-functionalized graphene (H-GO) has been established based on the enhancement of resonance Rayleigh scattering (RRS) intensity. The characteristics of RRS spectra, the optimum reaction conditions, and the reaction mechanism have been investigated. In this experiment, the Al(III) would exist in sol–gel Al(OH)3 species under the condition of pH 5.9 in aqueous solutions. When H-GO existed in the solution, the sol–gel Al(OH)3 would react with H-GO and result in enhancement of RRS intensity, owing to the enhanced hydrophobicity of H-GO surface. Therefore, a simple and rapid sensor for Al(III) was developed. The increased intensity of RRS is directly proportional to the concentration of Al(III) in the range of 10 nM–6 μM, along with a detection limit of 0.87 nM. Moreover, the sensor has been applied to determination of Al(III) concentration in real water and aspirin tablet samples with satisfactory results. Therefore, the proposed method is promising as an effective means for selective and sensitive determination of Al(III).
Co-reporter:Shi Gang Liu, Na Li, Yu Ling, Bei Hua Kang, Shuo Geng, Nian Bing Li, and Hong Qun Luo
Langmuir 2016 Volume 32(Issue 7) pp:1881-1889
Publication Date(Web):February 1, 2016
DOI:10.1021/acs.langmuir.6b00201
We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media.
Co-reporter:Shu Min Lin, Shuo Geng, Na Li, Nian Bing Li, Hong Qun Luo
Talanta 2016 Volume 151() pp:106-113
Publication Date(Web):1 May 2016
DOI:10.1016/j.talanta.2016.01.028
•A facile fluorescent sensor for detection of Hg2+ based on DPA-CuNPs was fabricated.•Preparation of the DPA-CuNPs with strong fluorescence is very simple and low-cost.•Hg2+ can disperse the aggregated DPA-CuNPs, leading to the fluorescence quenching.•The method shows high sensitivity and selectivity for Hg2+ detection.Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270 nm). Scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg2+ in the 1.0–30 μM concentration range and the detection limit (3σ/slope) is 32 nM. The method was successfully applied to determine Hg2+ in real water samples.
Co-reporter:Cui Ye, Min Qiang Wang, Zhong Feng Gao, Ying Zhang, Jing Lei Lei, Hong Qun Luo, and Nian Bing Li
Analytical Chemistry 2016 Volume 88(Issue 23) pp:
Publication Date(Web):November 7, 2016
DOI:10.1021/acs.analchem.6b02481
The efficiency of photon-to-electron conversion is extremely restricted by the electron–hole recombinant. Here, a new photoelectrochemical (PEC) sensing platform has been established based on the signal amplification of click chemistry (CC) via hybridization chain reaction (HCR) for highly sensitive microRNA (miRNA) assay. In this proposal, a preferred electron donor dopamine (DA) was first assembled with designed ligation probe (probe-N3) via amidation reaction to achieve DA-coordinated signal probe (PDA-N3). The PDA-N3 served as a flexible trigger to signal amplification through efficiently suppressing the electron–hole recombinant. Specifically, the PDA-N3 can be successfully ligated into the trapped hairpins (H1 and H2) via the superior ligation method of metal-catalyst-free CC, in which the electron donor DA was introduced into the assay system. Moreover, the enzyme-free HCR, employed as a versatile amplification way, ensures that lots of PDA-N3 can be attached to the substrate. This PEC sensing for miRNA-141 detection illustrated the outstanding linear response to a concentration variation from 0.1 fM to 0.5 nM and a detection limit down to 27 aM, without additional electron donors. The sensor is further employed to monitor miRNA-141 from prostate carcinoma cell (22Rv1), showing good quantitative detection capability. This strategy exquisitely influences the analytical performance and offers a new PEC route to highly selective and sensitive detection of biological molecules.
Co-reporter:Bei Hua Kang, Zhong Feng Gao, Na Li, Yan Shi, Nian Bing Li, Hong Qun Luo
Talanta 2016 Volumes 156–157() pp:141-146
Publication Date(Web):15 August 2016
DOI:10.1016/j.talanta.2016.05.006
•Thiazole orange serves as a fluorescent probe recognizing i-motif structure change.•The i-motif based sensor enables the detections of Ag+ and Cys at neutral pH.•The Ag+ and Cys detection procedures are label-free.•This method avoids tedious operation and is rapidly completed within 10 min.Silver ions have been widely applied to many fields and have harmful effects on environments and human health. Herein, a label-free optical sensor for Ag+ detection is constructed based on thiazole orange (TO) as a fluorescent probe for the recognition of i-motif DNA structure change at neutral pH. Ag+ can fold a C-rich single stranded DNA sequence into i-motif DNA structure at neutral pH and that folding is reversible by chelation with cysteine (Cys). The DNA folding process can be indicated by the fluorescence change of TO, which is non-fluorescent in free molecule state and emits strong fluorescence after the incorporation with i-motif DNA. Thus, a rapid, sensitive, and selective method for the detection of Ag+ and Cys is developed with a detection limit of 17 and 280 nM, respectively. It is worth noting that the mechanism underlying the increase of the fluorescence of thiazole orange in the presence of i-motif structure is explained. Moreover, a fluorescent DNA logic gate is successfully designed based on the Ag+/Cys-mediated reversible fluorescence changes. The proposed detection strategy is label-free and economical. In addition, this system shows a great promise for i-motif/TO complex to analyze Ag+ in the real samples.
Co-reporter:Zhong Feng Gao, Ting Ting Li, Xiao Lei Xu, Yi Yao Liu, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2016 Volume 83() pp:134-141
Publication Date(Web):15 September 2016
DOI:10.1016/j.bios.2016.04.041
•Green light-emitting polyepinephrine fluorescent organic dots are presented.•The PEP-FODs is used to detect Fe2+, Fe3+, and Cu2+.•The detection procedures of metal ions are label free and rapid.•The PEP-FODs possess good solubility, low cytotoxicity, and biocompatibility.In this paper, we present a class of bio-dots, polyepinephrine (PEP)-based fluorescent organic dots (PEP-FODs) for selective and sensitive detection of Fe2+, Fe3+, and Cu2+. The PEP-FODs were derived from epinephrine via self-polymerization at relatively low temperature down to 60 °C with low cytotoxicity and relative long lifetime (7.24 ns). The surface morphology and optical properties of the synthesized PEP-FODs were characterized. We found that the diameters of PEP-FODs were mainly distributed in the narrow range of 2–4 nm with an average diameter of 2.9 nm. An optimal emission peak located at 490 nm was observed when the green light-emitting PEP-FODs were excited at 400 nm. It is discovered that Fe2+, Fe3+, and Cu2+can strongly quench the fluorescence of PEP-FODs through the nonradiative electron-transfer. The detection limit of 0.16, 0.67, and 0.15 μM was obtained for Fe2+, Fe3+, and Cu2+, respectively. The independent sensing platform of Fe2+, Fe3+, and Cu2+could be established by using NaF as a complexing agent and by regulating the reaction time between NaF and metal ions. Cell viability studies reveal that the as-prepared PEP-FODs possess good solubility and biocompatibility, making it as excellent imaging nanoprobes for intracellular Fe2+, Fe3+, and Cu2+sensing. The developed PEP-FODs might hold great promise to broaden applications in nanotechnology and bioanalysis.
Co-reporter:Zhong Feng Gao, Yan Li Huang, Wang Ren, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2016 Volume 78() pp:351-357
Publication Date(Web):15 April 2016
DOI:10.1016/j.bios.2015.11.070
•A new signal amplification strategy based on guanine nanowire is proposed.•Guanine nanowire based amplification strategy was used for DNA and protein assay.•The detection limits were improved by two orders of magnitude using this strategy.Sensitive and specific detection of nucleic acids and proteins plays a vital role in food, forensic screening, clinical and environmental monitoring. There remains a great challenge in the development of signal amplification method for biomolecules detection. Herein, we describe a novel signal amplification strategy based on the formation of guanine nanowire for quantitative detection of nucleic acids and proteins (thrombin) at room temperature. In the presence of analytes and magnesium ions, the guanine nanowire could be formed within 10 min. Compared to the widely used single G-quadruplex biocatalytic label unit, the detection limits are improved by two orders of magnitude in our assay. The proposed enzyme-free method avoids fussy chemical label-ling process, complex programming task, and sophisticated equipment, which might provide an ideal candidate for the fabrication of selective and sensitive biosensing platform.
Co-reporter:Na Li, Xia Hao, Bei Hua Kang, Zhen Xu, Yan Shi, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics 2016 Volume 77() pp:525-529
Publication Date(Web):15 March 2016
DOI:10.1016/j.bios.2015.10.004
•Enzyme-free DNA detection was developed based on HCR and Fe3O4@PDA NPs.•Signal amplification was achieved by hybridization chain reaction.•Fe3O4@PDA NPs were used for homogeneous and rapid HCR products capture efficiently.•The strategy could distinguish single-base mismatched DNA sequence.A novel, highly sensitive assay for quantitative determination of DNA is developed based on hybridization chain reaction (HCR) amplification and the separation via core–shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs). In this assay, two hairpin probes are designed, one of which is labeled with a 6-carboxyfluorescein (FAM). Without target DNA, auxiliary hairpin probes are stable in solution. However, when target DNA is present, the HCR between the two hairpins is triggered. The HCR products have sticky ends of 24 nt, which are much longer than the length of sticky ends of auxiliary hairpins (6 nt) and make the adsorption much easier by Fe3O4@PDA NPs. With the addition of Fe3O4@PDA NPs, HCR products could be adsorbed because of the strong interaction between their sticky ends and Fe3O4@PDA NPs. As a result, supernatant of the solution with target DNA emits weak fluorescence after separation by magnet, which is much lower than that of the blank solution. The detection limit of the proposed method is as low as 0.05 nM. And the sensing method exhibits high selectivity for the determination between perfectly complementary sequence and target with single base-pair mismatch. Importantly, the application of the sensor for DNA detection in human serum shows that the proposed method works well for biological samples.
Co-reporter:Hong Guo Chen, Wang Ren, Jing Jia, Ji Feng, Zhong Feng Gao, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics 2016 Volume 77() pp:40-45
Publication Date(Web):15 March 2016
DOI:10.1016/j.bios.2015.09.027
•Signal amplified and background suppressed strategy for DNA detection is developed.•This new strategy is based on paired hairpin probes, Exo III and SYBR green I.•The assay is label-free, sensitive, specific and easy to practice.•The proposed method is applicable for detecting other DNA sequences.We describe here a fluorometric assay for sensitive detection of oligonucleotides, based on a target recycling amplification strategy driven by toehold-mediated strand displacement reaction and on exonuclease III (Exo Ш)-assisted fluorescence background suppression strategy. The network consists of a pair of partially complementary DNA hairpins (HP1 and HP2) with 3′ overhang ends, between which the spontaneous hybridization is kinetically hindered by the stems. The target DNA is repeatedly used to trigger a recycling progress between the hairpins, generating numerous HP1–HP2 duplex complexes. Exo III was then employed to digest the double strand parts of the residual hairpins and the intermediate products. The fluorescent dye, SYBR Green I, binds to the double-strand DNA products and emits strong fluorescence to achieve sensitive detection of the target DNA with the detection limit of 5.34 pM. Moreover, this proposed strategy showed high discrimination efficiency towards target DNA against mismatched DNA and was successfully applied in the analysis of human serum sample.
Co-reporter:Wang Ren, Long Yin Zhou, Ying Zhang, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2016 Volume 223() pp:24-29
Publication Date(Web):February 2016
DOI:10.1016/j.snb.2015.09.050
•Reusable and signal-on electrochemical sensor was developed.•The label-free and enzyme-free strategy greatly depressed the detection cost.•A target-dependent supersandwich mechanism showed outstanding selectivity.•A ternary self-assembled monolayer strategy greatly improved the reproducibility.•A dumbbell-shape DNA was used to recognize target-DNA.A reusable and label-free supersandwich biosensor was constructed for sensitive DNA detection by immobilizing target-triggered DNA concatamers with redox-active intercalators on ternary self-assembled monolayer (TSAM). Interestingly, the target DNA (T-DNA) could hybridize with the inert dumbbell-shaped DNA (D-DNA) to form a duplex DNA containing two sticky termini. The duplex DNA was then hybridized with the capture DNA (C-DNA) and the DNA concatamer reaction proceeded. The ternary self-assembly method was chosen to obtain the low-density C-DNA without reciprocal winding on the gold electrode for high-efficient concatamers hybridization. Hexaammineruthenium chloride was herein used as an electrochemical probe and could intercalate into the groove of double-helix DNA via electrostatic effect. The resultant supersandwich biosensor showed a high sensitivity for the T-DNA detection and a linear dependence between the reduction peak currents and logarithm of T-DNA concentrations in the range of 100.0 fM–10.0 nM with a relatively low detection limit of 30.0 fM. Moreover, the proposed biosensor exhibited favorable specificity and regenerability, and provided a new alternative to detect various target analytes by changing the sequence of capture probe and dumbbell probes, holding great potential for early diagnosis in gene-related diseases.
Co-reporter:Na Li;Xia Hao;Bei Hua Kang;Nian Bing Li
Luminescence 2016 Volume 31( Issue 4) pp:1025-1030
Publication Date(Web):
DOI:10.1002/bio.3069
Abstract
This work proposed a rapid and novel fluorescence-sensing system using a complex of acridine orange (AO) and polystyrene sulfonate (PSS) to sensitively recognize and monitor cetyltrimethylammonium bromide (CTAB) in an aqueous medium. AO can interact with PSS and a complex is formed via electrostatic attraction and hydrophobic interaction. The fluorescence of AO is greatly quenched after the introduction of PSS. Upon its subsequent addition, CTAB can interact and form a complex with PSS because the electrostatic attraction between CTAB and PSS is much stronger than that between AO and PSS, which results in significant fluorescence recovery. Interestingly, the proposed method can be applied for the discrimination and detection of surfactants with different hydrocarbon chain lengths due to their different binding affinity toward PSS. The detection limit for CTAB is as low as 0.2 µg/mL and the linear range is from 0.5 to 3.5 µg/mL. Moreover, we applied the sensor to the successful detection of CTAB in water samples. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Ting Liu, Na Li, Jiang Xue Dong, Hong Qun Luo, Nian Bing Li
Sensors and Actuators B: Chemical 2016 Volume 231() pp:147-153
Publication Date(Web):August 2016
DOI:10.1016/j.snb.2016.02.141
•A new fluorescent sensor for detection of Hg(II) and cysteine based on Mg-N-CQDs was fabricated.•Preparation of the Mg-N-CQDs is very simple and low-cost.•The method shows good sensitivity and selectivity for Hg(II) and cysteine detection.•An IMPLICATION logic gate was successfully constructed to mimic this experiment.Novel magnesium and nitrogen co-doped carbon quantum dots (Mg-N-CQDs) were developed as a fluorescent switch for sensitive and selective sensing of Hg(II) and cysteine (Cys). The Mg-N-CQDs synthesized by hydrothermal method possess high fluorescence intensity. However, after the addition of Hg(II), the fluorescence of Mg-N-CQDs aqueous solution was dramatically quenched, which may be attributed to the formation of non-fluorescent complex between Mg-N-CQDs and Hg(II). Interestingly, the fluorescence of the Mg-N-CQDs aqueous solution containing Hg(II) could be recovered gradually in the presence of Cys, due to the stronger binding affinity of Hg(II) toward Cys than toward Mg-N-CQDs. Based on these phenomena, a fluorescent probe for detection of Hg(II) and Cys was explored, and further applied to detect Hg(II) in real water samples with satisfactory results. Moreover, an IMPLICATION logic gate was constructed using Hg(II)/Cys as inputs and the fluorescence signal of Mg-N-CQDs as an output.
Co-reporter:Bang Lin Li;Hao Lin Zou;Lu Lu;Yu Yang;Jing Lei Lei;Nian Bing Li
Advanced Functional Materials 2015 Volume 25( Issue 23) pp:3541-3550
Publication Date(Web):
DOI:10.1002/adfm.201500180
Size-dependent optical absorption of semiconductive (2H) layered molybdenum disulfide (MoS2), exhibiting great discrimination abilities to single- and double-stranded DNA (ssDNA) and (dsDNA), is studied. In the presence of high concentration of salt, layered MoS2 trends to aggregate rapidly, leading to the increases of sizes in both vertical and lateral dimensions of the nanosheets, which results from the interplay between van der Waals attraction and electrical double-layer repulsion. Meanwhile, the aggregation behavior of layered MoS2 is remarkably inhibited by the synergistic effects of DNA oligonucleotides. ssDNA can adsorb on the surface of layered MoS2, resulting in a great dispersion, even in the presence of high concentration of salt, while the dispersion behavior is weakened when ssDNA is replaced by dsDNA. Whereas compared to graphene with zero bandgap energy, layered MoS2, with semiconductive properties, exhibits great characteristic optical absorption in visible wavelength region devoted to exploring the aggregation behavior of layered MoS2. Therefore, DNA oligonucleotides induced size control of layered MoS2, contributing to the regular change of its characteristic absorption in visible region, is considered a label-free bioassay for the detection of single-nucleotide polymorphism. Due to its easy operation and high specificity, it is expected that the proposed assay holds great promise for further applications.
Co-reporter:Yu Ling, Zhong Feng Gao, Qian Zhou, Nian Bing Li, and Hong Qun Luo
Analytical Chemistry 2015 Volume 87(Issue 3) pp:1575
Publication Date(Web):January 9, 2015
DOI:10.1021/ac504023b
A multidimensional optical sensing platform which combines the advantages of resonance Rayleigh scattering (RRS), fluorescence, and colorimetry has been designed for detection of heparin. Phloxine B, a fluorescein derivative showing the special RRS spectrum in the long wavelength region, was selected to develop an easy-to-get system which can achieve switch-on sensing to obtain high sensitivity. The noise level of RRS in the long wavelength region is much weaker, and the reproducibility is much better; in this way, the sensitivity and selectivity can be improved. In the absence of heparin, the phloxine B and polyethyleneimine (PEI) form a complex through electrostatic interaction. Thus, the RRS signal at 554 nm is low; the phloxine B fluorescence is quenched, and the absorption signal is low. In the presence of heparin, competitive binding occurred between phloxine B and heparin toward PEI; then, phloxine B is gradually released from the phloxine B/PEI complex, causing obvious enhancement of the RRS, fluorescence, and absorption signals. Besides, the desorption of phloxine B is less effective for the heparin analogues, such as hyaluronic acid and chondroitin sulfate. In addition, the system presents a low detection limit of heparin to 5.0 × 10–4 U mL–1 and can also be applied to the detection of heparin in heparin sodium injection and 50% human serum samples with satisfactory results. Finally, the potential application of this method in reversible on–off molecular logic gate fabrication was discussed using the triple-channel optical signals as outputs.
Co-reporter:Yu Ling, Fei Qu, Qian Zhou, Ting Li, Zhong Feng Gao, Jing Lei Lei, Nian Bing Li, and Hong Qun Luo
Analytical Chemistry 2015 Volume 87(Issue 17) pp:8679
Publication Date(Web):August 3, 2015
DOI:10.1021/acs.analchem.5b01138
Multicolor polymer nanoparticles (or dots) were prepared via the reaction between hyperbranched polyethyleneimine (PEI) and aldehydes, and when the concentration of aldehydes was lower, the final mixture displayed gelation behavior. This phenomenon can be applied to visual detection of aldehydes. Moreover, the colors of the polymer dots and gel are varied by using different kinds of aldehydes, which can be utilized for visual discrimination of aldehydes. For simplicity, we focus our attention on the interaction between PEI and formaldehyde. The nanoparticles show an average diameter of 42 nm, emit bright cyan fluorescence with high quantum yield, and exhibit high water dispersibility and excellent photostability. Due to the advantages, our polymer nanoparticles (PNPs) are utilized as a fluorescent probe for imaging in living SK-N-SH cells. Furthermore, valuable explorations have been carried out on the fundamental properties of PNPs, such as concentration-dependent fluorescence, pH-dependent fluorescence, and solvent effect.
Co-reporter:Zhong Feng Gao, Dong Mei Chen, Jing Lei Lei, Hong Qun Luo, Nian Bing Li
Analytica Chimica Acta 2015 Volume 897() pp:10-16
Publication Date(Web):15 October 2015
DOI:10.1016/j.aca.2015.09.045
•Conformational switch of i-motif is used for the detection of glucose and urea.•The sensor can be regenerated.•The proposed method is successfully applied in real sample assay.•Our method is label-free and inexpensive.Improving the reproducibility of electrochemical signal remains a great challenge over the past decades. In this work, i-motif oligonucleotide probe-based electrochemical DNA (E-DNA) sensor is introduced for the first time as a regenerated sensing platform, which enhances the reproducibility of electrochemical signal, for label-free detection of glucose and urea. The addition of glucose or urea is able to activate glucose oxidase-catalyzed or urease-catalyzed reaction, inducing or destroying the formation of i-motif oligonucleotide probe. The conformational switch of oligonucleotide probe can be recorded by electrochemical impedance spectroscopy. Thus, the difference of electron transfer resistance is utilized for the quantitative determination of glucose and urea. We further demonstrate that the E-DNA sensor exhibits high selectivity, excellent stability, and remarkable regenerated ability. The human serum analysis indicates that this simple and regenerated strategy holds promising potential in future biosensing applications.
Co-reporter:Na Li, Zhong Feng Gao, Bei Hua Kang, Nian Bing Li and Hong Qun Luo
RSC Advances 2015 vol. 5(Issue 26) pp:20020-20024
Publication Date(Web):10 Feb 2015
DOI:10.1039/C4RA17059H
Based on the nicking endonuclease (NEase)-assisted target recycling and magnetic nanoparticle (MNPs) separation process via the streptavidin–biotin system, we developed a new, signal amplified and ultrasensitive fluorescent biosensor for the detection of mutant human p53 gene. The target mutant DNA hybridizes with the loop portion of a hairpin probe (HP) modified with biotin and a fluorescein isothiocyanate dye (FITC) at its 5′ and 3′ ends separately and forms a nicking site for NEase, which cleaves the HP and releases the target DNA. The released target DNA again hybridizes with the intact HP and initiates the DNA recycling process with the assistance of NEase, leading to the cleavage of a large number of HPs and detachment of the biotin labeled part with the FITC tagged signal portion. Only these cleaved fragments corresponding to target DNAs could remain in solution and function as a signaling flare, while the biotin labeled sequences including intact hairpin probes could be trapped and removed by the streptavidin coated MNPs. The developed method exhibits a detection limit as low as 198 fM and high discrimination efficiency toward a single-base mismatched sequence. Therefore, the novel NEase-amplified magnetic nanoparticle assay has great potential for sensitive and accurate detection of trace amounts of DNA in clinical diagnosis and biomedical research.
Co-reporter:Jiang Xue Dong, Fei Qu, Nian Bing Li and Hong Qun Luo
RSC Advances 2015 vol. 5(Issue 8) pp:6043-6050
Publication Date(Web):15 Dec 2014
DOI:10.1039/C4RA14812F
This paper reports a dramatic cyclic regeneration of polyethyleneimine-templated silver nanoclusters (PEI-AgNCs) based on the pH-induced conformational changes of polyethyleneimine (PEI) in aqueous solution. The PEI-AgNCs have been synthesized and found to be highly sensitive to the pH of the solution in air. The studies show that small AgNCs would gather to form larger silver nanoparticles (AgNPs) by adjusting the pH to 1.5 with a nitric acid solution. The AgNPs in solution was then transformed gradually to Ag(I) ions with stirring in air. Subsequently, the above Ag(I) ions were reduced again to AgNCs by changing the pH to about 9 with a NaOH solution and adding a certain amount of formaldehyde as a reductant to solution. The fluorescence and UV-visible absorption spectra recorded this process in detail. The transmission electron microscopy images, X-ray powder diffraction patterns, and Fourier transform infrared spectra further demonstrated that the cyclic transformation existed among AgNCs, AgNPs, and Ag(I) ions. The amino-rich PEI plays a crucial role in the regeneration of PEI-AgNCs. A large number of amino groups on PEI could be reversibly protonated by adjusting the pH of solution, leading to a change of the interaction between Ag and PEI, which has laid foundation for this work.
Co-reporter:Xia Hao, Zhen Xu, Na Li, Nian Bing Li and Hong Qun Luo
Analytical Methods 2015 vol. 7(Issue 9) pp:3849-3854
Publication Date(Web):31 Mar 2015
DOI:10.1039/C5AY00815H
A simple and sensitive electrochemical method for the detection of cetyltrimethylammonium bromide (CTAB) by cation exchange processes has been developed. The rationale for the amperometric CTAB assay is essentially based on the different binding affinities of polystyrene sulfonate (PSS) toward electrochemically active acridine orange (AO) and electrochemically inactive CTAB. The stronger binding affinity of the PSS toward CTAB than toward AO essentially validates the amperometric CTAB assay through a cation exchange mechanism with the decrease in the redox peak current of AO adsorbed on the PSS. Because of the different binding affinities between PSS and cationic surfactants with different lengths of the alkyl chain, this method can be used to detect quaternary ammonium surfactants with similar structures. The difference value of the anodic peak current showed a linear relationship with the CTAB concentration in a concentration range from 0.5 to 20 μg mL−1 and a detection limit of 0.3 μg mL−1 was obtained. More importantly, this detection method has been successfully applied to the detection of CTAB in real samples.
Co-reporter:Yu Ling
The Journal of Physical Chemistry C 2015 Volume 119(Issue 48) pp:27173-27177
Publication Date(Web):November 9, 2015
DOI:10.1021/acs.jpcc.5b09488
The solvent-dependent properties of polyethyleneimine (PEI)-capped Cu nanoclusters are discussed in this study. The PEI-encapsulated Cu nanoclusters were dispersed in 12 polar organic solvents, and in water and alcohols, the nanoclusters display similar properties and could be stable in the dark. Moreover, Cu nanoclusters exhibit a blue shift of the emission peak in tetrahydrofuran (THF) and 1,4-dioxane, and the absorption spectra change dramatically. Furthermore, in THF the fluorescence intensity increases significantly over time. Besides, the absorption spectra also display a significant change in acetonitrile, dimethyl sulfoxide, and ethylene glycol monomethyl ether, while the emission bands show no obvious shift. In acetonitrile, THF, and 1,4-dioxane, the solvents look milky under bright light, and the fluorescence colors look more blue under a UV lamp. The solvent effect on the fluorescence and absorption spectra of the PEI-capped Cu nanoclusters in water–THF mixtures at different solvent ratios is discussed. Additionally, it should be noticed that the solvent effect of PEI-capped Cu nanoclusters described in this paper is different from the reported solvatofluorochromic properties of PEI-capped Ag nanoclusters. Furthermore, a possible mechanism was explored to explain the solvent-dependent properties of PEI-Cu nanoclusters.
Co-reporter:Wang Ren, Ying Zhang, Wei Tao Huang, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics 2015 Volume 68() pp:266-271
Publication Date(Web):15 June 2015
DOI:10.1016/j.bios.2015.01.010
•Self-blocking of hairpin DNA and signal-on mechanism avoided false positive results.•Hg2+ triggers Exo III-aided target recycling coupling with DNAzyme amplification.•Even 1.0 nM Hg2+ can be identified by the naked eye.•The sensor showed outstanding selectivity for Hg2+ against the coexisting metal ions.•The assay required no probe modification and complicated instrument.This work reported a label-free colorimetric assay for sensitive detection of Hg2+ based on Hg2+-triggered hairpin DNA probe (H-DNA) termini-binding and exonuclease Ш (Exo Ш)-assisted target recycling, as well as hemin/G-quadruplex (DNAzyme) signal amplification. The specific binding of free Hg2+ with the thymine–thymine (T–T) mismatches termini of H-DNA could immediately trigger the Exo Ш digestion, and then set free G-quadruplex segments and Hg2+. The Exo Ш impellent recycling of ultratrace Hg2+ produced numerous G-quadruplexes. The corresponding DNAzymes catalyzed efficiently the H2O2-mediated oxidation of the ABTS2− to the colored product in the presence of hemin. Using the color change as the output signal, and the Exo Ш-aided Hg2+ recycling and DNAzyme as the signal amplifier, the ultrasensitive assay system successfully achieved visual detection of Hg2+ as low as 1.0 nM by the naked eye, and was suitable for field monitoring. The calibration curve was linear in the range of 50.0 pM to 20.0 nM for Hg2+ (R=0.9962) with a detection limit of 10.0 pM. Moreover, this proposed strategy showed excellent selectivity, portability and low-cost, and was successfully applied to colorimetric detection of Hg2+ in laboratory tap water and Jialing river water samples.
Co-reporter:Jian Rong Zhang, Wei Tao Huang, Ai Lian Zeng, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2015 Volume 64() pp:597-604
Publication Date(Web):15 February 2015
DOI:10.1016/j.bios.2014.09.092
•Ethynyl triggered enhanced fluorescence quenching effect was first reported.•The quenching mechanism triggered by ethynyl was discussed in detail.•A simple, rapid, and sensitive Hg2+ sensor was constructed.•The Hg2+-sensitive property excelled that of molecular beacon.•A simple, rapid, and sensitive cysteine sensor was developed.Ethynyl triggered enhanced fluorescence quenching effect was first reported based on photoinduced electron transfer (PET) between fluorophore and ethynyl. Ethynyl and 6-carboxyl-fluorescein (FAM) were labeled at the 5′- and 3′-termini of a poly d(T) sequence containing three thymine units, respectively. In the presence of Hg2+, Hg2+ binds to two thymine residues through T–Hg2+–T interactions and the formed T–Hg2+–T base pairs bring FAM and ethynyl from two matched sequences into close proximity. On the one hand, π-stacked T–Hg2+–T mediates and accepts electron transfer of the excited state of FAM and quenches the fluorescence through PET. On the other hand, π-stacked interactions between ethynyl and FAM also provide a de-excitation process for the excited state of FAM via PET and trigger an enhanced fluorescence quenching. On the basis of fluorescence quenching, a simple, rapid, and sensitive Hg2+ sensor was constructed; under optimum conditions, a good linear relationship was obtained over the concentration range of 5–150 nM for Hg2+ and a very low detection limit (0.42 nM) was reached. The developed system was further designed as a cysteine (Cys) sensor based on fluorescence recovery resulted from the strong interaction between Cys and Hg2+; the proposed Cys sensor has a linear range of 10–550 nM and a detection limit of 2.5 nM. The two sensors were used for analysis of real samples and the satisfactory results were achieved.
Co-reporter:Lu Lu, Jing Cao Si, Zhong Feng Gao, Yu Zhang, Jing Lei Lei, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2015 Volume 63() pp:14-20
Publication Date(Web):15 January 2015
DOI:10.1016/j.bios.2014.07.007
•The sensor is more selective than apatmer-based ones due to enzyme specificity.•DNAzyme generated by ligation reaction is used to amplify signal response.•The dual strategy is firstly applied for electrochemical sensing system.•This biosensor has been applied successfully to ATP detection in real sample.A dual strategy that combines the adenosine triphosphate (ATP)-dependent enzymatic ligation reaction with self-cleaving DNAzyme-amplified electrochemical detection is employed to construct the biosensor. In this design, the methylene blue-labeled hairpin-structured DNA was self-assembled onto a gold electrode surface to prepare the modified electrode through the interaction of Au–S bond. In the procedure of ATP-dependent ligation reaction, when the specific cofactor ATP was added, the two split oligonucleotide fragments of 8-17 DNAzyme were linked by T4 DNA ligase and then released to hybridize with the labeled hairpin-structured DNA substrate. The linked 8-17 DNAzyme catalyzes the cleavage of the hairpin-structured substrate by the addition of Zn2+, causing the methylene blue which contains high electrochemical activity to leave the surface of the gold electrode, therefore generating a dramatic decrease of electrochemical signal. The decrease of peak current was readily measured by square wave voltammetry and a relatively low detection limit (0.05 nM) was obtained with a linear response range from 0.1 to 1000 nM. By taking advantage of the highly specific cofactor dependence of the DNA ligation reaction, the proposed ligation-induced DNAzyme cascades demonstrate ultrahigh selectivity toward the target cofactor ATP. A catalytic and molecular beacons strategy is further adopted to amplify the electrochemical signal detection achieved by cycling and regenerating the 8-17 DNAzyme to realize enzymatic multiple turnover, thus one DNAzyme can catalyze the cleavage of several hairpin-structured substrates, which improves the sensitivity of the newly designed electrochemical sensing system.
Co-reporter:Wang Ren, Zhong Feng Gao, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics 2015 Volume 63() pp:153-158
Publication Date(Web):15 January 2015
DOI:10.1016/j.bios.2014.07.028
•Ultralow background and signal-on mechanism avoid false positive results.•Dual signal amplification was achieved by coupling Exo-III catalysis with HCR.•The strategy improved the sensitivity for detection of T-DNA down to 1.0 fM.•This protocol could detect T-DNA with a linear range of 6 orders of magnitude.This work reported a novel, ultrasensitive, and selective platform for electrochemical detection of DNA, employing an integration of exonuclease III (Exo-III) assisted target recycling and hybridization chain reaction (HCR) for the dual signal amplification strategy. The hairpin capture probe DNA (C-DNA) with an Exo-III 3′ overhang end was self-assembled on a gold electrode. In the presence of target DNA (T-DNA), C-DNA hybridized with the T‐DNA to form a duplex region, exposing its 5′ complementary sequence (initiator). Exo-III was applied to selectively digest duplex region from its 3-hydroxyl termini until the duplex was fully consumed, leaving the remnant initiator. The intact T-DNA spontaneously dissociated from the structure and then initiated the next hybridization process as a result of catalysis of the Exo-III. HCR event was triggered by the initiator and two hairpin helper signal probes labeled with methylene blue, facilitating the polymerization of oligonucleotides into a long nicked dsDNA molecule. The numerous exposed remnant initiators can trigger more HCR events. Because of integration of dual signal amplification and the specific HCR process reaction, the resultant sensor showed a high sensitivity for the detection of the target DNA in a linear range from 1.0 fM to 1.0 nM, and a detection limit as low as 0.2 fM. The proposed dual signal amplification strategy provides a powerful tool for detecting different sequences of target DNA by changing the sequence of capture probe and signal probes, holding a great potential for early diagnosis in gene-related diseases.
Co-reporter:Peng Wang, Bang Lin Li, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2015 Volume 135() pp:198-202
Publication Date(Web):25 January 2015
DOI:10.1016/j.saa.2014.06.082
•Gold nanoclusters as fluorescent probes were applied to detection of d-penicillamine.•A novel and simple fluorescent sensor was established for d-penicillamine detection.•The novel fluorescent assay exhibited high sensitivity and low spectral interference.•This method was potentially useful in medicine assay in analytical chemistry.In this contribution, a luminescent gold nanoclusters which were synthesized by bovine serum albumin as novel fluorescent probes were successfully utilized for the determination of d-penicillamine for the first time. Cupric ion was employed to quench the strong fluorescence of the gold nanoclusters, whereas the addition of d-penicillamine caused obvious restoration of fluorescence intensity of the Cu2+-gold nanoclusters system. Under optimum conditions, the increment in fluorescence intensity of Cu2+-gold nanoclusters system caused by d-penicillamine was linearly proportional to the concentration of d-penicillamine in the range of 2.0 × 10−5–2.39 × 10−4 M. The detection limit for d-penicillamine was 5.4 × 10−6 M. With the off–on fluorescence signal at 650 nm approaching the near-infrared region, the present sensor for d-penicillamine detection had high sensitivity and low spectral interference. Furthermore, the novel gold nanoclusters-based fluorescent sensor has been applied to the determination of d-penicillamine in real biological samples with satisfactory results.Graphical abstract
Co-reporter:Zhong Feng Gao, Wei Wei Song, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2015 Volume 65() pp:360-365
Publication Date(Web):15 March 2015
DOI:10.1016/j.bios.2014.10.061
•Resonance Rayleigh scattering method is used for sensitive detection of Hg2+.•The sensitivity of the sensing system is better than previous reports.•The sensor relies on non-crosslinking aggregation of AuNPs.•The proposed method is successfully applied in real sample assay.This work describes a sensitive approach utilizing non-cross-linking aggregation of double-stranded DNA modified gold nanoparticles (dsDNA-AuNPs) for the detection of mercury ions (Hg2+) by resonance Rayleigh scattering (RRS) method for the first time. The double-stranded DNA contains a mismatched T–T base pair in the chain terminus, resulting in a flexible DNA tail and preventing the AuNPs from aggregation. Thus, a low RRS signal is obtained. However, in the presence of Hg2+, the non-cross-linking aggregation of dsDNA-AuNPs occurs, due to the Hg2+-mediated coordination of T–Hg2+–T base pair. The aggregation of nanoparticles generates a high RRS value. Particularly, the solution color and ultraviolet–visible absorption barely changed under the same conditions, while it is capable of detecting by RRS method with a low detection limit (0.4 nM), which is 1000-fold lower than that of the colorimetric method. The proposed method was successfully applied to the detection of Hg2+ in real samples. The sensitive and selective assay might be inspiring for the development of new detectors for other metal ions or biomolecules.Graphical Abstract
Co-reporter:Bang Lin Li, Ling Xiao Chen, Hao Lin Zou, Jing Lei Lei, Hong Qun Luo and Nian Bing Li
Nanoscale 2014 vol. 6(Issue 16) pp:9831-9838
Publication Date(Web):25 Jun 2014
DOI:10.1039/C4NR02592J
Electrochemically induced Fenton (electro-Fenton) reaction was used for efficient and controllable preparation of hydroxyl radicals, leading to the generation of luminescent quantum dots through etching of as-exfoliated MoS2 nanosheets. Morphologic changes of MoS2 nanosheets during the electro-Fenton reaction were monitored using transmission electron microscopy, showing that etching of MoS2 nanosheets induced by hydroxyl radicals resulted in rapid homogeneous fracturing of the sheets into small dots via a transition of nanoporous morphology. The as-generated dots with vertical dimensional thickness of ca. 0.7 nm and plane size of ca. 5 nm were demonstrated to be MoS2 quantum dots (MoS2-QDs), and their photoluminescence properties were explored based on quantum confinement, edge effect, and intrinsic characteristics. Moreover, the degree of etching and the concomitant porosity of MoS2 nanosheets could be conveniently tuned via the electro-Fenton reaction time, resulting in a new morphology of nanoporous MoS2 nanosheets, with potential new applications in various significant areas.
Co-reporter:Wei Tao Huang, Hong Qun Luo, and Nian Bing Li
Analytical Chemistry 2014 Volume 86(Issue 9) pp:4494
Publication Date(Web):April 16, 2014
DOI:10.1021/ac5004008
The most serious, and yet unsolved, problem of constructing molecular computing devices consists in connecting all of these molecular events into a usable device. This report demonstrates the use of Boolean logic tree for analyzing the chemical event network based on graphene, organic dye, thrombin aptamer, and Fenton reaction, organizing and connecting these basic chemical events. And this chemical event network can be utilized to implement fluorescent combinatorial logic (including basic logic gates and complex integrated logic circuits) and fuzzy logic computing. On the basis of the Boolean logic tree analysis and logic computing, these basic chemical events can be considered as programmable “words” and chemical interactions as “syntax” logic rules to construct molecular search engine for performing intelligent molecular search query. Our approach is helpful in developing the advanced logic program based on molecules for application in biosensing, nanotechnology, and drug delivery.
Co-reporter:Xia Hao, Jing Lei Lei, Nian Bing Li, Hong Qun Luo
Analytica Chimica Acta 2014 Volume 852() pp:63-68
Publication Date(Web):10 December 2014
DOI:10.1016/j.aca.2014.09.012
•An anion-exchange-based amperometry for sodium dodecyl sulfate detection is proposed.•Preparation of eosin Y/polyethyleneimine electrode is simple, rapid and low-cost.•The method enlarged the detection range and reduced the sample volume dramatically.•The sensor shows high sensitivity and good selectivity in interfering species.•High accuracy and good recoveries are obtained for analysis of real samples.A simple and effective method for the detection of electrochemically inactive sodium dodecyl sulfate (SDS) has been designed, based on different binding affinity of polyethyleneimine (PEI) toward electrochemically active eosin Y and electrochemically inactive SDS. The stronger binding affinity of the PEI toward SDS than eosin Y results in the decrease of the redox peak current of surface confined eosin Y and provides a quantitative readout for the SDS. The difference in value of the cathodic peak current showed a linear relationship with SDS concentration in a concentration range from 1 to 40 μg mL−1, and a detection limit of 0.9 μg mL−1 for SDS was obtained. Furthermore, the method has been successfully applied to the detection of SDS in real samples. The developed approach provided a simple and reliable detection for SDS and might have potential applications in electrochemical methods for inactive molecules.
Co-reporter:Jian Rong Zhang, Zhong Ling Wang, Fei Qu, Hong Qun Luo, and Nian Bing Li
Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 28) pp:6592-6599
Publication Date(Web):June 27, 2014
DOI:10.1021/jf4054534
A highly sensitive folic acid (FA) detection method based on the fluorescence quenching of polyethylenimine-capped silver nanoclusters (PEI-AgNCs) was put forward. In the sensing system, FA and PEI-AgNCs were brought into close proximity to each other by electrostatic interaction, and a two-step electron-transfer process, in which the electron was transferred from FA to AgNCs through PEI molecule, led to fluorescence quenching. The fluorescence quenching efficiency of PEI-AgNCs was linearly related to the concentration of FA over the range from 0.1 nM to 2.75 μM. Good linear correlation (R2 = 0.9981) and a detection limit of 0.032 nM were obtained under optimum conditions. Moreover, the proposed method was used for the determination of FA in real samples with satisfactory results, and those coexistent substances could not cause any significant decrease in the fluorescence intensity of AgNCs. Therefore, the proposed research system is of practical significance and application prospects.
Co-reporter:Xi Yuan Zhang, Hong Qun Luo, Nian Bing Li
Analytical Biochemistry 2014 Volume 455() pp:55-59
Publication Date(Web):15 June 2014
DOI:10.1016/j.ab.2014.03.015
Abstract
A simple pH-induced electrochemical switch based on an i-motif structure is developed by using crystal violet as a selective electrochemical probe for the i-motif structure. Thiol-modified cytosine-rich single-strand oligonucleotide (C-rich ssDNA) can be self-assembled on the gold electrode surface via gold–sulfur interaction. Crystal violet is employed as an electrochemical probe for the i-motif structure because of its capability of binding with the i-motif structure through an end-stacking mode. In acidic aqueous solution, crystal violet may approach the electrode surface owing to the formation of the i-motif structure, resulting in an obvious signal, so-called “ON” state. Whereas in neutral or basic aqueous solution, the i-motif structure unfolds to dissociative single strand, which causes crystal violet to leave from the electrode surface, and a weak signal is obtained, so-called “OFF” state. In addition, in the range of pH 4.6–7.3, the increase in current has a good linear relationship (R = 0.989) with pH value in the testing solutions. This pH-driven electrochemical switch has the advantages of simplicity, sensitivity, high selectivity, and good reversibility. Furthermore, it provides a possible platform for pH measurement.
Co-reporter:Jing Cao Si, Lu Lu, Zhong Feng Gao, Yu Zhang, Hong Qun Luo and Nian Bing Li
Analytical Methods 2014 vol. 6(Issue 16) pp:6536-6540
Publication Date(Web):17 Jun 2014
DOI:10.1039/C4AY00843J
A sensitive and selective biosensor has been developed to detect the hydroxyl radical (˙OH), which was generated through the Fenton reaction. ˙OH could oxidatively damage DNA and cleave it into pieces. Based on this, taking [Ru(NH3)6]3+ as the electrochemical indicator, ˙OH was determined on a gold electrode with self-assembled DNA. The resulting electrochemical biosensor showed a wide linear range of detection from 125 pM to 625 nM with a detection limit of 80 pM and satisfactory selectivity.
Co-reporter:Wei Tao Huang, Jian Rong Zhang, Wan Yi Xie, Yan Shi, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2014 Volume 57() pp:117-124
Publication Date(Web):15 July 2014
DOI:10.1016/j.bios.2014.01.055
•We report a label-free optic sensor for sensing of G-quadruplex DNA, HO∙, and Fe2+.•Dyes-graphene is used as a nanofilter and nanoswitch to detect target analytes.•Our graphene-based system combines the merits of nanotechnology and fuzzy theory.•Fuzzy logic can solve non-linear problems of fluorescence sensor.•Fuzzy logic analysis can transform numerical inputs into linguistic outputs.Herein, by combining the merits of nanotechnology and fuzzy logic theory, we develop a simple, label-free, and general strategy based on an organic dye-graphene hybrid system for fluorescence intelligent sensing of G-quadruplexes (G4) formation, hydroxyl radical (HO∙), and Fe2+ in vitro. By exploiting acridine orange (AO) dyes-graphene as a nanofilter and nanoswitch and the ability of graphene to interact with DNA with different structures, our approach can efficiently distinguish, quantitatively detect target analytes. In vitro assays with G4DNA demonstrated increases in fluorescence intensity of the AO–rGO system with a linear range of 16–338 nM and a detection limit as low as 2.0 nM. The requenched fluorescence of the G4TBA–AO–rGO system has a non-linear response to Fenton reagent. But this requenching reduces the fluorescence intensity in a manner proportional to the logarithm to the base 10 of the concentration of Fenton reagent in the range of 0.1–100 μM and 100–2000 μM, respectively. Furthermore, we develop a novel and intelligent sensing method based on fuzzy logic which mimics human reasoning, solves complex and non-linear problems, and transforms the numerical output into the language description output for potential application in biochemical systems, environmental monitoring systems, and molecular-level fuzzy logic computing system.
Co-reporter:Yu Ling, Na Zhang, Fei Qu, Ting Wen, Zhong Feng Gao, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2014 Volume 118() pp:315-320
Publication Date(Web):24 January 2014
DOI:10.1016/j.saa.2013.08.097
•Cu nanoclusters with size smaller than 2 nm was utilized as a fluorescence probe.•The lable-free method had good selectivity, low toxicity, and low cost.•Cu nanoclusters using polyethyleneimine as a template possessed good stability.•Water-soluble Cu nanoclusters had been applied successfully in human serum sample.An interesting, simple, and label-free strategy for the detection of hydrogen peroxide and glucose has been developed with polyethyleneimine (PEI)-capped copper nanoclusters as a fluorescence probe in aqueous solution. The PEI-templated Cu nanoclusters which we have synthesized have an average diameter of 1.8 nm and show a blue emission at 480 nm. In the presence of hydrogen peroxide, the fluorescence of the Cu nanoclusters is quenched. Similarly, glucose oxidase catalyzes the oxidation of glucose to gluconic acid and H2O2, so we can also use this probe to detect glucose. Because of the high zymolyte specificity of glucose oxidase, the detection of glucose has good selectivity. Under the optimized experimental conditions, the linear ranges for H2O2 and glucose are 0.5–10 μM and 10–100 μM, respectively. And the detection limits for H2O2 and glucose are 0.4 and 8 μM, respectively. Furthermore, we discussed the mechanism of fluorescence quenching which is caused by the interaction between H2O2 and Cu nanoclusters. This sensing system has been applied successfully to the detection of glucose in human serum samples.As a label-free fluorescence probe in aqueous solution, polyethyleneimine-capped copper nanoclusters were applied to the detection of H2O2 and glucose.
Co-reporter:Ting Wen, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2014 192() pp: 673-679
Publication Date(Web):
DOI:10.1016/j.snb.2013.11.012
Co-reporter:Fei Qu, Li Li Dou, Nian Bing Li and Hong Qun Luo
Journal of Materials Chemistry A 2013 vol. 1(Issue 25) pp:4008-4013
Publication Date(Web):25 Apr 2013
DOI:10.1039/C3TC30168K
The solvatochromism of metal nanoclusters is still a highly debatable topic. In this work, based on hyperbranched polyethyleneimine (PEI)-encapsulated Ag nanoclusters, we present some interesting results on the chemical environment-responsive fluorescence of Ag nanoclusters in 11 different solvents, which may shed some light on this issue. In water and alcohols, the nanoclusters emit intense blue fluorescence; when they are dispersed in water–tetrahydrofuran (THF) mixtures, the fluorescent color changes from intense blue (in pure water) to intense yellow (in pure THF); when they are dispersed in ethylene glycol monomethyl ether, the fluorescence changes from blue to green over time. However, while the fluorescence emission changes, no obvious band shift is exhibited in the absorption features of Ag nanoclusters. Therefore, the PEI-capped Ag nanoclusters show obvious solvatofluorochromic but not solvatochromic properties. Furthermore, the emission from these clusters can also be tuned from blue to yellow by changing the concentration of the Ag nanoclusters.
Co-reporter:Jing Rong Chen, Xiao Xia Jiao, Hong Qun Luo and Nian Bing Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 6) pp:861-864
Publication Date(Web):13 Dec 2012
DOI:10.1039/C2TB00267A
Two novel probe-label-free electrochemical aptasensors based on methylene blue (MB)-anchored graphene oxide (GO) amplification were developed for thrombin (TB) and ATP detection, taking advantage of the specific binding affinity of the aptamer towards the target and the different affinities of GO for MB, ssDNA, dsDNA, and G-quadruplex.
Co-reporter:Yan Shi, Hong Qun Luo and Nian Bing Li
Chemical Communications 2013 vol. 49(Issue 55) pp:6209-6211
Publication Date(Web):24 May 2013
DOI:10.1039/C3CC42140F
The RRS intensities are significantly increased only when a parallel-stranded G-quadruplex is added to Mg2+ solution owing to the formation of G-wires between them, but the others cannot. So, we constructed a new and highly sensitive RRS method to discriminate a parallel-stranded G-quadruplex from DNA with other topologies and structures.
Co-reporter:Ting Wen, Nian Bing Li, and Hong Qun Luo
Analytical Chemistry 2013 Volume 85(Issue 22) pp:10863
Publication Date(Web):October 21, 2013
DOI:10.1021/ac402241m
A novel sensing system has been designed for the detection of sodium dodecyl sulfate (SDS) based on the recovered fluorescence signal of eosin Y and polyethyleneimine (PEI) complex. The eosin Y reacted with PEI to form a complex by virtue of hydrophobic interaction as well as the electrostatic interaction, which resulted in a strong fluorescence quenching of the eosin Y. Subsequently, with the addition of SDS to the eosin Y/PEI system, a strong surface interaction and electrostatic interactions between PEI and SDS resulted in the formation of the PEI/SDS complex and the dissociation of the eosin Y/PEI complex, which led to the significant fluorescence recovery. Herein, we have demonstrated that this facile methodology can offer a rapid, reliable, and selective detection of SDS with a detection limit as low as 0.02 μg mL–1 and a linear range from 0.4 to 6 μg mL–1. Furthermore, the method has been successfully applied to the detection of SDS in real samples with satisfied recovery and accuracy. Overall, these results demonstrate that this method has great promise for environmental applications.
Co-reporter:Na Zhang, Fei Qu, Hong Qun Luo, Nian Bing Li
Analytica Chimica Acta 2013 Volume 791() pp:46-50
Publication Date(Web):12 August 2013
DOI:10.1016/j.aca.2013.06.045
•Polyethyleneimine-capped silver nanoclusters were label-free, cost-effective.•This method for copper ions detection possesses a fluorescence signal-on response.•This sensor for copper ions was selective, simple, and highly sensitive.In this work, we present a label-free sensor for copper ions. This sensor is composed of silver nanoclusters and cysteine. The fluorescence of the silver nanoclusters was quenched by cysteine, which was recovered in the presence of copper ions. This binding of silver nanoclusters to cysteine promoted agglomeration of silver nanoclusters to yield larger non-fluorescent silver nanoparticles. The presence of copper ions resulted in the oxidation of cysteine to form a disulfide compound, leading to recovery of fluorescence of the silver nanoclusters. The fluorescence of the silver nanoclusters in the presence of cysteine increased with increasing concentration of copper ions in the range of 10–200 nM. The detection limit of this sensor for copper ions was 2.3 nM. The silver nanoclusters–cysteine sensor provides a simple, cost-effective, and sensitive platform for the detection of copper ions.A signal-on method to monitor copper ions is proposed based on the suppression of cysteine-induced fluorescence quenching of silver nanoclusters by copper ions.
Co-reporter:Gang Lin Wang, Long Yin Zhou, Hong Qun Luo, Nian Bing Li
Analytica Chimica Acta 2013 Volume 768() pp:76-81
Publication Date(Web):20 March 2013
DOI:10.1016/j.aca.2013.01.026
The present work demonstrates a novel signal-off electrochemical method for the determination of DNA methylation and the assay of methyltransferase activity using the electroactive complex [Ru(NH3)6]3+ (RuHex) as a signal transducer. The assay exploits the electrostatic interactions between RuHex and DNA strands. Thiolated single strand DNA1 was firstly self-assembled on a gold electrode via Au–S bonding, followed by hybridization with single strand DNA2 to form double strand DNA containing specific recognition sequence of DNA adenine methylation MTase and methylation-responsive restriction endonuclease Dpn I. The double strand DNA may adsorb lots of electrochemical species ([Ru(NH3)6]3+) via the electrostatic interaction, thus resulting in a high electrochemical signal. In the presence of DNA adenine methylation methyltransferase and S-adenosyl-l-methionine, the formed double strand DNA was methylated by DNA adenine methylation methyltransferase, then the double strand DNA can be cleaved by methylation-responsive restriction endonuclease Dpn I, leading to the dissociation of a large amount of signaling probes from the electrode. As a result, the adsorption amount of RuHex reduced, resulting in a decrease in electrochemical signal. Thus, a sensitive electrochemical method for detection of DNA methylation is proposed. The proposed method yielded a linear response to concentration of Dam MTase ranging from 0.25 to 10 U mL−1 with a detection limit of 0.18 U mL−1 (S/N = 3), which might promise this method as a good candidate for monitoring DNA methylation in the future.Graphical abstractA novel and highly sensitive signal-off electrochemical method to monitor DNA methylation and DNA adenine methylation methyltransferase activity is proposed.Highlights► An electrochemical strategy for sensing DNA methylation and DNA methyltransferase activity was proposed. ► A methylation-responsive DNA biosensor was fabricated. ► This assay was based on electrostatic adsorption of [Ru(NH3)6]3+ on the anionic DNA biosensor. ► A low detection limit (0.18 U mL−1) was obtained without any amplification. ► This strategy can be applied to qualification of activity of other methyltransferases.
Co-reporter:Xi Yuan Zhang, Long Yin Zhou, Hong Qun Luo, Nian Bing Li
Analytica Chimica Acta 2013 Volume 776() pp:11-16
Publication Date(Web):7 May 2013
DOI:10.1016/j.aca.2013.03.030
•A label-free impedimetric sensor is constructed for DNA sequences detection.•The key point is adjunct probes immobilized nearby capture probes.•The biosensor achieves simple and highly selective detection for DNA sequence.•The sensor is readily extended for other biomolecules, proteins and mRNAs detection.A highly sensitive and label-free impedimetric biosensor is achieved based on an adjunct probe attached nearby the capture probe. In this work, the adjunct probe was co-assembled on the surface of gold electrode with the capture probe hybridized with the reporter probe, and then 6-mercapto-1-hexanol was employed to block the nonspecific binding sites. When target DNA was added, the adjunct probe functioned as a fixer to immobilize the element of reporter probe displaced by the target DNA sequences and made the reporter probe approach the electrode surface, leading to effective inhibition of charge transfer. The increase in charge transfer resistance is related to the quantity of the target DNA in a wide range. The linear range for target DNA with specific sequences was from 0.1 nM to 0.5 μM with a good linearity (R = 0.9988) and a low detection limit of 6.3 pM. This impedimetric biosensor has the advantages of simplicity, sensitivity, good selectivity, and large dynamic range.Using an adjunct probe for highly sensitive and label-free detection of DNA sequence based on electrochemical impedance spectroscopy was achieved.
Co-reporter:Bang Lin Li, Jing Rong Chen, Hong Qun Luo, Nian Bing Li
Journal of Electroanalytical Chemistry 2013 Volume 706() pp:64-68
Publication Date(Web):1 October 2013
DOI:10.1016/j.jelechem.2013.08.001
•AgNCs stabilized by PEI were confirmed as a novel electrocatalytic material.•A novel electrochemical sensor of H2O2 was prepared based on Ag nanoclusters.•A low detection limit for H2O2 was obtained at the AgNCs modified electrode.Silver nanoclusters (AgNCs) synthesized by using polyethyleneimine as a stabilizing scaffold have been confirmed as a novel material to exhibit high electrocatalytic activity for the reduction of hydrogen peroxide in this paper. The novel hydrogen peroxide electrochemical sensor was originally prepared based on the excellent electrocatalytic activity for the reduction of hydrogen peroxide at the polyethyleneimine-templated silver nanoclusters modified glassy carbon electrode (PEI/AgNCs–GCE). To achieve the optimum electrocatalytic activity for the reduction of hydrogen peroxide, the pH of the buffer solution and concentration of immobilizing AgNCs solution were optimized. Under optimum conditions, the PEI/AgNCs–GCE revealed a highly linear response to H2O2 in the concentration of 10–1440 μmol L−1 with a detection limit of 1.8 μmol L−1. Compared to some silver nanoparticles modified electrodes, the novel electrochemical sensor based on AgNCs exhibited a better electrocatalytic activity for the reduction of H2O2 and a lower detection limit for the determination of H2O2.Graphical abstractThe novel electrochemical sensor of H2O2 was developed based on the excellent electrocatalytic activity of Ag nanoclusters using the polyethyleneimine-stabilized Ag nanoclusters modified glassy carbon electrode.
Co-reporter:Xiao Xia Jiao, Hong Qun Luo, Nian Bing Li
Journal of Electroanalytical Chemistry 2013 Volume 691() pp:83-89
Publication Date(Web):15 February 2013
DOI:10.1016/j.jelechem.2012.12.013
A mixture of graphene oxide and tetrachloroauric acid were directly electrochemical co-reduced on a glassy carbon electrode (GCE) through cyclic voltammetry (CV). A graphene–gold nanocomposite film modified GCE was fabricated and used to investigate the electrochemical behavior of 4-nitrophenol by CV, electrochemical impedance spectroscopy, chronocoulometry and linear sweep voltammetry. Compared with the bare GCE and the gold nanoparticles modified GCE, it was found that the oxidation signal of 4-nitrophenol was remarkably improved at the graphene–gold nanocomposite film modified GCE. The experimental parameters such as the types of buffer solutions, the pH of supporting electrolyte, the amounts of deposits, the accumulation time and potential were optimized. Under the optimum experimental conditions, the oxidation peak currents were proportional to the 4-nitrophenol concentration in the range of 3.6 × 10−8–9.0 × 1 0−5 M with a detection limit of 1.0 × 10−8 M (S/N = 3). The modified electrode which presented high sensitivity, good repeatability and stability was applied to the direct determination of 4-nitrophenol in river water samples.Graphical abstract.Highlights► A novel graphene–gold nanocomposite film modified GCE has been fabricated. ► The oxidation signal of 4-nitrophenol was remarkably improved at the modified GCE. ► This sensitive sensor has nearly wide dynamic range and low LOD.
Co-reporter:Jun Hua Luo, Xiao Xia Jiao, Nian Bing Li, Hong Qun Luo
Journal of Electroanalytical Chemistry 2013 Volume 689() pp:130-134
Publication Date(Web):15 January 2013
DOI:10.1016/j.jelechem.2012.10.013
This paper presents a new electrochemical method for the determination of Cd(II) using a bismuth-modified multiwalled carbon nanotubes doped carbon paste electrode (Bi/MCNTs-CPE). Because of good electrical conductivity of MCNTs and excellent electroanalytical performance of bismuth film, the new electrode significantly enhances the sensitivity for the detection of Cd(II) and exhibits superior performance in comparison to the bare carbon paste electrode, the bismuth-modified carbon paste electrode, and the multiwalled carbon nanotubes doped carbon paste electrode. Many parameters such as mass ratio of carbon paste and MCNTs, pH of measure solution, concentration of Bi(III), preconcentration time, preconcentration potential, and operational parameters of square wave anodic stripping voltammetry were investigated. Under optimum conditions, the linear regression equation of Cd(II) was ip = 4.458c − 11.73 (ip: μA, c: μg L−1, R = 0.9983) from 1.0 to 60 μg L−1 with a detection limit of 0.3 μg L−1. Finally, the Bi/MCNTs-CPE was successfully applied to the determination of Cd(II) in tap water sample with satisfactory results.Highlights► Bismuth-modified carbon nanotube doped carbon paste electrode was easily fabricated. ► Advantage of bismuth film and doped carbon nanotubes was effectively combined. ► The optimum mass ratio of carbon paste to carbon nanotubes is 6.6. ► The novel electrode significantly enhances signal for detection of Cd(II).
Co-reporter:Zhong Feng Gao, Jian Bang Gao, Long Yin Zhou, Yu Zhang, Jin Cao Si, Hong Qun Luo and Nian Bing Li
RSC Advances 2013 vol. 3(Issue 30) pp:12334-12340
Publication Date(Web):07 May 2013
DOI:10.1039/C3RA40810H
This paper reports a simple method to immediately functionalize ssDNA onto gold electrodes using a low pH-induced and high salt concentration solution route. Electrochemical impedance spectroscopy, cyclic voltammetry, and chronocoulometry were used to characterize the ssDNA self-assembled monolayer (SAM). The effects of pH, ionic strength, and ssDNA sequences for DNA adsorption were investigated. It was found that thiolated ssDNA can be attached to gold electrodes using a low pH-induced route in a high salt concentration solution. A synergistic effect between pH and the salt has been suggested by studying the fundamental kinetics. The surface coverage of 3.054 × 1013 molecules/cm2 in pH 3.4 buffer was higher than that of 4.574 × 1012 molecules/cm2 in pH 7.4 buffer. The ssDNA on the gold surface was functional and was able to recognize complementary DNA strands.
Co-reporter:Jiang Xue Dong, Nian Bing Li and Hong Qun Luo
Analytical Methods 2013 vol. 5(Issue 20) pp:5541-5548
Publication Date(Web):14 Aug 2013
DOI:10.1039/C3AY41055B
The formation of zirconium hexacyanoferrate(II) nanoparticles has been developed as a new resonance Rayleigh scattering (RRS) platform for the sensitive detection of trace amounts of dopamine (DA). The determination mechanism is based on dopamine reacting with hexacyanoferrate(III) ions to produce hexacyanoferrate(II) ions in acidic solution, which further react with zirconium ions to produce zirconium hexacyanoferrate(II) complexes. The zirconium hexacyanoferrate(II) complexes aggregate to form zirconium hexacyanoferrate(II) nanoparticles with an average diameter of about 50 nm. This aggregation can produce a strong RRS signal with the wavelength maximum at about 318 nm. This sensing system presented a good linear relationship between the increment of scattering intensity (ΔIRRS) and the concentration of dopamine in the range of 0.03–1.3 μg mL−1 with a correlation coefficient of 0.9996 and a low detection limit (at a signal-to-noise ratio of 3) of 0.392 ng mL−1. Furthermore, this reaction system has been applied successfully to the detection of DA in a pharmaceutical preparation, and the recoveries were between 100.78% and 104.43%.
Co-reporter:Xiao Xia Jiao, Jing Rong Chen, Xi Yuan Zhang, Hong Qun Luo, Nian Bing Li
Analytical Biochemistry 2013 Volume 441(Issue 2) pp:95-100
Publication Date(Web):15 October 2013
DOI:10.1016/j.ab.2013.07.023
Abstract
A sensitive chronocoulometric aptasensor for the detection of thrombin has been developed based on gold nanoparticle amplification. The functional gold nanoparticles, loaded with link DNA (LDNA) and report DNA (RDNA), were immobilized on an electrode by thrombin aptamers performing as a recognition element and capture probe. LDNA was complementary to the thrombin aptamers and RDNA was noncomplementary, but could combine with [Ru(NH3)6]3+ (RuHex) cations. Electrochemical signals obtained by RuHex that bound quantitatively to the negatively charged phosphate backbone of DNA via electrostatic interactions were measured by chronocoulometry. In the presence of thrombin, the combination of thrombin and thrombin aptamers and the release of the functional gold nanoparticles could induce a significant decrease in chronocoulometric signal. The incorporation of gold nanoparticles in the chronocoulometric aptasensor significantly enhanced the sensitivity. The performance of the aptasensor was further increased by the optimization of the surface density of aptamers. Under optimum conditions, the chronocoulometric aptasensor exhibited a wide linear response range of 0.1–18.5 nM with a detection limit of 30 pM. The results demonstrated that this nanoparticle-based amplification strategy offers a simple and effective approach to detect thrombin.
Co-reporter:Peng Wang, Jiang Xue Dong, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 103() pp:38-44
Publication Date(Web):15 February 2013
DOI:10.1016/j.saa.2012.10.067
We present here a resonance Rayleigh scattering (RRS) spectrum method for the determination of melamine at the nanogram level using a gemini surfactant (disodium 4-dodecyl-2,4′-oxydibenzenesulfonate, DDOF). It was found that DDOF could react with cationic melamine to form an ion-association complex, which induced the enhancement of RRS intensity and the appearance of a new RRS spectrum in acetate buffer (pH 3.6). The RRS spectral characteristics of the melamine-DDOF system, the optimum conditions of the reaction, and the influencing factors have been investigated. Under optimum conditions, the enhanced RRS intensity was proportional to the concentration of melamine in the range of 0.38–6.30 μg/mL. The method has high sensitivity, and the detection limit for melamine is 8.48 ng/mL. Furthermore, the reaction mechanism and the reasons of RRS enhancement were evaluated.Graphical abstractHighlights► We report the reaction of DDOF with melamine by resonance Rayleigh scattering (RRS). ► A sensitive, simple, and rapid RRS method has been developed for melamine detection. ► The detection limit for melamine reached nanogram level. ► The method was applied successfully to the determination of melamine in milk sample. ► The possible mechanism for the RRS enhancement of melamine-DDOF system was discussed.
Co-reporter:Sheng Tian Huang, Ling Feng Yang, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics 2013 Volume 42() pp:136-140
Publication Date(Web):15 April 2013
DOI:10.1016/j.bios.2012.10.093
We report on an ultrasensitive and selective fluorescence assay for Sudan I and III against the influence of Sudan II and IV based on ligand exchange mechanism. Calcein as a fluorescence indicator and Sudan I–IV as model analytes were employed to investigate the analytical feature of this assay platform. Results show that the fluorescence of calcein can be efficiently quenched by Cu(II). When the ligand exchange reaction proceeds, calcein is deprived of Cu(II) by Sudan I and III, resulting in the fluorescence recovery of calcein. However, the ligand exchange reaction does not happen in the presence of Sudan II or IV due to the 2-methyl steric effects, which is favorable for selective determination of Sudan I and III against the influence of Sudan II and IV. It was found that the fluorescence enhancement efficiency (FEE) against the concentration of Sudan (cSudan, nmol L−1) shows a linear relationship. The calibration equations are FEESudan I=0.0032 cSudan I−0.02613, and FEESudan III=0.0033 cSudan III−0.02467 over the corresponding linear range of 11.25–2078.29 and 9.44–1035.78 nmol L−1 with the correlation coefficients (R2) of 0.9984 and 0.9955, respectively. And the detection limits (3σ/slope) are calculated to be 211.3 and 208.5 pmol L−1 for Sudan I and III, respectively, showing ultralow detection limit. The Sudan dye in a commercial chilli powder sample was assayed with satisfactory results.Highlights► A turn on fluorescence assay for Sudan I and III was developed. ► Sudan I and III can restore the fluorescence of Cu(II)–calcein. ► Sudan II and IV with 2-methyl cannot restore the fluorescence of Cu(II)–calcein. ► Sudan I and III can be detected against the influence of Sudan II and IV. ► This method shows an ultralow detection limit down to pmol L−1level.
Co-reporter:Na Zhang, Fei Qu, Hong Qun Luo, Nian Bing Li
Biosensors and Bioelectronics 2013 Volume 42() pp:214-218
Publication Date(Web):15 April 2013
DOI:10.1016/j.bios.2012.10.090
In this work, we present a label-free biosensor for the sensing of biothiols such as cysteine, homocysteine, and glutathione. This biosensor is based on the fluorescent probe, polyethyleneimine-capped silver nanoclusters. The selective binding of silver nanoclusters to biothiols promotes the silver nanoclusters agglomeration to yield larger non-fluorescent silver nanoparticles. And the fluorescence intensity of silver nanoclusters was quenched efficiently with increasing concentration of biothiols. The other amino acids introduced to the silver nanoclusters probe solution did not quench the fluorescence of the probe as they do not have thiol group which has strong affinity to the silver nanoclusters. Thus, this biosensor allowed selectively investigation of biothiols. The as-proposed biosensor was sensitive for the detection of biothiols. The linear ranges for cysteine, homocysteine, and glutathione were 0.1–10 μΜ (R2=0.9930), 0.1–10 μΜ (R2=0.9924), and 0.5–6 μΜ (R2=0.9900), respectively. The detection limits for cysteine, homocysteine, glutathione were 42, 47, and 380 nΜ, respectively. The silver nanoclusters-based fluorescent biosensor provides a simple, cost-effective, and sensitive platform for the detection of biothiols.Highlights► Polyethyleneimine-capped silver nanoclusters were label-free and easily fabricated. ► A mechanism of agglomeration of silver nanoclusters caused by biothiols is proposed. ► This biosensor for biothiols is highly sensitive, selective, and simple. ► This assay of biothiols can be simply visualized with the nakedeyes.
Co-reporter:Fei Qu, Nian Bing Li, and Hong Qun Luo
Langmuir 2013 Volume 29(Issue 4) pp:1199-1205
Publication Date(Web):January 2, 2013
DOI:10.1021/la304558r
Silver nanoclusters capped by hyperbranched polyethylenimine (PEI) have been developed as a highly sensitive fluorescent and colorimetric pH sensor. The probe responds rapidly to pH fluctuations and has such absorption characteristics that the color changes from the colorless or a nearly colorless state to a colored state with increasing acidity, so PEI-capped Ag nanoclusters could be used as a color indicator for colorimetric pH detection. Quantitatively, the fluorescence intensity of PEI-capped Ag nanoclusters exhibits a linear fashion over the pH range of 5.02–7.96 and increases by around 10-fold approximately with greater fluorescence at higher pH values. The repulsion development and conformational change of PEI with decreasing pH induce the aggregation of Ag nanoclusters, leading to an obvious color change and fluorescence quenching of Ag nanoclusters at low pH values. As expected, the pH probe is also sensitive to the different buffer solutions, except for those containing some anions that could react with Ag nanoclusters. Besides, the ionic strength of the buffers has a little influence on the pH-responsive behavior. Our pH sensor with nanoscaled physical dimensions would be a promising candidate in the applications in biological, medical, and pharmaceutical fields.
Co-reporter:Jun Hua Luo, Bang Lin Li, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2013 Volume 186() pp:84-89
Publication Date(Web):September 2013
DOI:10.1016/j.snb.2013.05.074
A new electrochemical sensor was developed based on polyethyleneimine-functionalized graphene oxide (PEI-rGO) modified glassy carbon electrode (PEI-rGO/GCE). The synthetic positive charged PEI-rGO had good electron transfer ability, large specific surface area, prominent biocompatibility, and excellent adsorption. Its morphology and microstructure was characterized by scanning electron microscopy. The new electrode was firstly used for the detection of gallic acid, which exhibits superior performance in comparison to the bare glassy carbon electrode and graphene oxide modified glassy carbon electrode. The experimental conditions such as pH, adsorption time, and scan rate were optimized for the determination of gallic acid. Under optimum conditions, the linear regression equation of gallic acid was ip = 12.76c − 11.44 (ip: μA, c: mg/L, R = 0.9887) from 0.1 to 10 mg/L with a detection limit (S/N = 3) of 0.07 mg/L. The method has been successfully applied to the determination of gallic acid in samples of green tea and black tea.
Co-reporter:Bang Lin Li, Jun Hua Luo, Hong Qun Luo, Nian Bing Li
Sensors and Actuators B: Chemical 2013 Volume 186() pp:96-102
Publication Date(Web):September 2013
DOI:10.1016/j.snb.2013.05.091
A novel electrochemical sensor based on d-penicillamine (d-PA) molecularly imprinted polypyrrole film on a glassy carbon electrode was fabricated. The complementary cavities located on the surface of molecularly imprinted polypyrrole film were used for subsequent template recognition. It was confirmed that the molecularly imprinted polypyrrole modified glassy carbon electrode (MIP-GCE) showed greater recognition ability than the non-molecularly imprinted polypyrrole modified glassy carbon electrode (NIP-GCE). Considering the electrochemical oxidation of d-PA with ferrocyanide and the specific recognition of molecular imprinting technique, the highly selective determination of d-penicillamine was achieved on the d-PA molecularly imprinted polypyrrole modified glassy carbon electrodes using ferrocyanide as an electrochemical probe. Several factors affecting sensor response, such as film thickness, template concentration, and the pH of phosphate buffer solution, were investigated to achieve optimum electrochemical response to d-PA at the MIP-GCE. The MIP-GCE revealed highly linear behavior in the concentration range of 10.0–480.0 μmol L−1 with the detection limit of 3.5 μmol L−1 for d-PA. The novel sensor has been applied to the determination of d-PA in real biological samples with satisfactory results.The molecularly imprinted polypyrrole electrochemical sensor is prepared and applied to the determination of d-penicillamine.
Co-reporter:Fei Qu, Nian Bing Li, and Hong Qun Luo
The Journal of Physical Chemistry C 2013 Volume 117(Issue 7) pp:3548-3555
Publication Date(Web):January 30, 2013
DOI:10.1021/jp3091792
In this paper, an interesting process is described in the synthesis of silver nanoclusters capped by hyperbranched polyethyleneimine (PEI): a transition from nanoparticles to nanoclusters takes place spontaneously over time accompanied with the reappearance of size-dependent physicochemical properties of silver nanoclusters. The transmission electron microscopy images, X-ray powder diffraction patterns, and fluorescence and UV–visible spectra accurately record this process. As PEI-capped Ag particles were prepared by a heating process at 90 °C for 10 min and then a cooling process to ambient temperature, the average diameter changed from 5.3 nm after 24 h to 3.9 nm 168 h later, and the percentage of the particles of 1.0–2.0 nm increased significantly over 168 h. Meanwhile, the color of Ag colloid solutions changed from deep reddish brown to bright yellow with an obvious enhancement of fluorescence intensity. The “smart” ligand shell of PEI plays a key role in the size transition. It could tailor the nanoparticles to just the right size of nanoclusters, resulting in the color change and fluorescence recovery. Therefore, this work clearly exhibits the reappearance of size-dependent physicochemical properties of silver nanoclusters with size reduction in the range where the transition from metallic to molecular behavior takes place.
Co-reporter:Wan Yi Xie, Wei Tao Huang, Jian Rong Zhang, Hong Qun Luo and Nian Bing Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 23) pp:11479-11482
Publication Date(Web):04 May 2012
DOI:10.1039/C2JM31280H
A triple-channel optical signal probe has been designed for the detection of Hg2+ ions. In the absence of Hg2+, the thymine-rich ssDNA wrapped AuNPs were well dispersed. Thus, the colour of the solution is pink-red; the resonance light scattering (RLS) signal is low; the fluorescence of acridine orange (AO) is powerfully quenched. In the presence of Hg2+, the ssDNA formed a T–Hg2+–T configuration, which produces a colour change, RLS signal enhancement, and fluorescence of AO restoration. Under the optimum conditions, the system exhibits a dynamic response range for Hg2+ from 50 nM to 5 μM with a detection limit of 30 nM.
Co-reporter:Sheng Tian Huang, Yan Shi, Nian Bing Li and Hong Qun Luo
Chemical Communications 2012 vol. 48(Issue 5) pp:747-749
Publication Date(Web):28 Nov 2011
DOI:10.1039/C1CC15959C
We introduce a sensitive, rapid, label-free and general fluorescent method for the determination of tartrazine by competitive binding to reduced graphene oxide (rGO) against fluorescein, and the fluorescence recovery upon fluorescein desorption from rGO provides a quantitative readout for tartrazine, giving a detection limit of 0.53 ng mL−1.
Co-reporter:Wan Yi Xie, Wei Tao Huang, Nian Bing Li and Hong Qun Luo
Chemical Communications 2012 vol. 48(Issue 1) pp:82-84
Publication Date(Web):08 Nov 2011
DOI:10.1039/C1CC15449D
In the presence of graphene oxide, upon formation of cytosine–Ag–cytosine the fluorescence wavelength of FAM-labeled DNA exhibited a red shift, and its intensity significantly increased. A novel fluorescent DNA sensor for Ag+ and cysteine detection, and a dual-output fluorescent DNA INHIBIT logic gate are designed.
Co-reporter:Fei Qu, Nian Bing Li, and Hong Qun Luo
Analytical Chemistry 2012 Volume 84(Issue 23) pp:10373
Publication Date(Web):November 8, 2012
DOI:10.1021/ac3024526
Ag nanoclusters functioned by hyperbranched polyethyleneimine have been developed as a new fluorescent and colorimetric platform for sensitive and selective recognition of halide ions (e.g., Cl–, Br–, and I–). The recognition mechanism is based on the unique reactions between halide ions and the silver atoms. In particular, halide-induced oxidative etching and aggregation can produce a strong fluorescence quenching of Ag nanoclusters. This sensing system exhibits a remarkably high selectivity toward halide ions over most of anions and cations and shows good linear ranges and lower detection limits: the linear ranges are 0.5–80 μM for Cl–, 0.1–14 μM for Br–, and 0.05–6 μM for I–, respectively; the limits of detection for Cl–, Br–, and I–, at a signal-to-noise ratio of 3, are estimated to be 200, 65, and 40 nM, respectively. Specifically, Br– and I– could be recognized selectively in the coexistence with Cl– under the condition of higher ionic strength, which is a significant advantage in the detection of Br– and I– in real samples. In addition, the recognition of halide could be performed by the colorimetric method, which is also attractive and promising because of its simplicity, rapidity, reliability, and low cost. Furthermore, this sensing system has been applied successfully to the detection of Cl– in real water samples.
Co-reporter:Qin Cheng, Fei Qu, Nian Bing Li, Hong Qun Luo
Analytica Chimica Acta 2012 Volume 715() pp:113-119
Publication Date(Web):17 February 2012
DOI:10.1016/j.aca.2011.12.004
In this paper, 1-hexadecyl-3-methylimidazolium bromide (C16mimBr)-coated Fe3O4 magnetic nanoparticles (NPs) as an adsorbent of mixed hemimicelles solid-phase extraction was investigated for the preconcentration of two chlorophenols (CPs) in environmental water samples prior to HPLC with UV detection at 285 nm. The high surface area and excellent adsorption capacity of the Fe3O4 NPs after modification with C16mimBr were utilized adequately in the SPE process. By the rapid isolation of Fe3O4 NPs through placing a strong magnet on the bottom of beaker, the time-consuming preconcentration process of loading large volume sample in conventional SPE method with a column can be avoided. A comprehensive study of the adsorption conditions such as the zeta-potential of Fe3O4 NPs, added amounts of C16mimBr, pH value, standing time and maximal extraction volume were also presented. Under optimized conditions, two analytes of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were quantitatively determined. The method was then used to determine the two CPs in real environmental water samples. The accuracy of method was evaluated by recovery measurements on spiked samples. Good recovery results (74–90%) were achieved. It is important to note that satisfactory preconcentration factors and extraction recoveries for the two CPs were obtained with only a small amount of Fe3O4 NPs (40 mg) and C16mimBr (24 mg).Graphical abstractHighlights► C16mimBr-coated Fe3O4 magnetic nanoparticles acted as an adsorbent of mixed hemimicelles SPE. ► This SPE method was effective for concentrating chlorophenols prior to HPLC analysis. ► This approach was applied to determine the two chlorophenols in real environmental water samples.
Co-reporter:Ting Wen, Fei Qu, Nian Bing Li, Hong Qun Luo
Analytica Chimica Acta 2012 Volume 749() pp:56-62
Publication Date(Web):24 October 2012
DOI:10.1016/j.aca.2012.08.048
In this work, we utilized polyethyleneimine-capped silver nanoclusters (PEI-Ag nanoclusters) to develop a new fluorometric method for the determination of hydrogen peroxide and glucose with high sensitivity. The PEI-Ag nanoclusters have an average size of 2 nm and show a blue emission at 455 nm. The photostable properties of the PEI-Ag nanoclusters were examined. The fluorescence of the PEI-Ag nanoclusters could be particularly quenched by H2O2. The oxidization of glucose by glucose oxidase coupled with the fluorescence quenching of PEI-Ag nanoclusters by H2O2 can be used to detect glucose. Under optimum conditions, the fluorescence intensity quenched linearly in the range of 500 nM–100 μM with high sensitivity. The detection limit for H2O2 was 400 nM. And a linear correlation was established between fluorescence intensity (F0 − F) and concentration of glucose in the range of 1.0 × 10−6 to 1.0 × 10−5 M and 1.0 × 10−5 to 1.0 × 10−3 M with a detection limit of 8.0 × 10−7 M. The method was used for the detection of glucose in human serum samples with satisfactory results. Furthermore, the mechanism of sensitive fluorescence quenching response of Ag nanoclusters to glucose and H2O2 has been discussed.Graphical abstractHighlights► A new method for synthesis of Ag nanoclusters using polyethyleneimine as a stabilizing agent was developed. ► Water-soluble Ag nanoclusters possessed high fluorescence and excellent biocompatibility. ► A new approach for determination of glucose and H2O2 by fluorescence quenching was developed. ► The method for detecting glucose and H2O2 has high sensitivity, low toxicity, and easy operation. ► Ag nanoclusters has great potential for bioimaging.
Co-reporter:Long Yin Zhou, Xi Yuan Zhang, Gang Lin Wang, Xiao Xia Jiao, Hong Qun Luo and Nian Bing Li
Analyst 2012 vol. 137(Issue 21) pp:5071-5075
Publication Date(Web):28 Aug 2012
DOI:10.1039/C2AN35905G
The focus of this work was on designing a label-free DNA biosensor based on a super-sandwich assay using the electrochemical impedance spectroscopy technique. For this purpose, we designed a signal-up configuration whose linker probes could hybridize with two regions of the target DNA. In this configuration, the presented target DNA would effectively decrease the electron transfer, which would improve the sensitivity of the sensor. Ultimately, we employed gel electrophoresis to further confirm the formation of the proposed super-sandwich structure.
Co-reporter:Wan Yi Xie, Wei Tao Huang, Hong Qun Luo and Nian Bing Li
Analyst 2012 vol. 137(Issue 20) pp:4651-4653
Publication Date(Web):15 Aug 2012
DOI:10.1039/C2AN35777A
A new room-temperature phosphorescence (RTP) mercury ions sensor has been developed based on cetyltrimethylammonium bromide-capped Mn-doped ZnS quantum dots (CTAB/Mn-ZnS QDs) and label-free thymine (T)-rich aptamer. The formed T–Hg2+–T dsDNA can linearly quench the RTP of Mn-ZnS QDs through electron transfer and aggregation effect, and give a detection limit of 1.5 nM.
Co-reporter:Sheng Tian Huang, Yan Shi, Nian Bing Li and Hong Qun Luo
Analyst 2012 vol. 137(Issue 11) pp:2593-2599
Publication Date(Web):03 Apr 2012
DOI:10.1039/C2AN35099H
We report on a fast, sensitive, label-free, and general dye-sensor platform for synthetic organic dyes detection by competitive adsorption on reduced graphene oxide (rGO) against a fluorescent dye (FD). Fluorescein (Fl) as fluorescence indicator and a cationic dye methylene blue (MB) as model analyte were employed to investigate the analytical feature of this assay platform. An anionic dye sunset yellow FCF (SY) was chosen as a comparison analyte to test the generality of this strategy. Results show that rGO can bind Fl and quench the fluorescence by fluorescence resonance energy transfer (FRET), while MB can displace Fl quickly from the Fl/rGO complex by competitive adsorption, inducing the fluorescence recovery which provides a quantitative readout for MB. Besides, this design was simply based on the competitive adsorption of rGO between dye and FD, and can be generally applied to other dyes for label-free detection. The fluorescence enhancement efficiency (FEE) is proportional to the dye concentration over the range of 7.60–420.00 ng mL−1 MB and 7.28–400.25 ng mL−1 SY, respectively. The linear regression equations were calculated as FEEMB = 0.0192cMB − 0.3103 for MB and FEESY = 0.0142 cSY − 0.0427 for SY, with the detection limits of 1.03 and 1.15 ng mL−1, respectively. The MB in waste water and SY in an orange-flavored sports drink sample were assayed with satisfactory results.
Co-reporter:Nian Bing Li, Wei Wei Zhu, Jun Hua Luo and Hong Qun Luo
Analyst 2012 vol. 137(Issue 3) pp:614-617
Publication Date(Web):06 Dec 2011
DOI:10.1039/C1AN15753A
The development and use of ‘green’ electrode materials is extremely attractive for the routine use of disposable metal sensors. Bismuth is an environmentally-friendly element and a bismuth film electrode was proposed as an alternative to mercury film electrodes. Compared with bismuth, stannum is a more ‘environmentally friendly’ material. The stannum–bismuth composite film electrode prepared by the in situelectrodeposition of stannum and bismuth on the glassy carbon substrate is reported for the first time. Compared with bismuth film and stannum film electrodes, the stannum–bismuth composite film electrode revealed better electroanalytical performance, and can be used as a possible alternative electrode for electrochemical stripping analysis of trace heavy metals.
Co-reporter:Sheng Tian Huang, Gang Lin Wang, Nian Bing Li and Hong Qun Luo
RSC Advances 2012 vol. 2(Issue 29) pp:10948-10954
Publication Date(Web):11 Sep 2012
DOI:10.1039/C2RA21415F
The mechanism of the pH-induced aggregation reaction between melamine (Mel) and phosphate (Ps) has been studied using a combination of resonance Rayleigh scattering (RRS), FTIR, UV-visible spectra, and single-crystal X-ray and powder X-ray diffraction for the first time. The results confirm that the aggregation reaction between Mel and Ps is highly pH-dependent. Changes in pH dramatically influence the molar ratio of Mel to melaminium (Hmel+) and subsequently affect the synergistic nature of hydrogen bonding, electrostatic and π–π stacking interactions, resulting in the reversibility of the aggregation and dissolution process. The composition of the Mel–Ps aggregates has been characterized as 2[Hmel+]·[HPO42−]·3H2O. Mechanism analysis demonstrated that there exist two different methods for the transformation of Mel into Hmel+ by considering the aggregation reaction process and conditions.
Co-reporter:Wei Wei Song, Nian Bing Li, Hong Qun Luo
Analytical Biochemistry 2012 Volume 422(Issue 1) pp:1-6
Publication Date(Web):1 March 2012
DOI:10.1016/j.ab.2011.12.051
We present here a resonance Rayleigh scattering (RRS) method for the determination of heparin at the nanogram level using gemini surfactant (dodecyl polyoxyethylene ether biquaternary ammonium salt, DPBAS). It was found that DPBAS could react with anionic heparin to form an ion-association complex, which induced the enhancement of RRS intensity and the appearance of a new RRS spectrum in Britton–Robinson buffer (pH 5.5). The RRS spectral characteristics of the heparin–DPBAS system, the optimum conditions of the reaction, and the influencing factors have been investigated. Under the optimum conditions, the enhanced RRS intensity (ΔIRRS) was proportional to the concentration of heparin in the range of 0.05–0.6 μg/mL. The method has high sensitivity, and the detection limit for heparin is 4.3 ng/mL. The proposed method has been successfully applied for the determination of heparin in pharmaceutical samples. Furthermore, the mechanism of the interaction between heparin and DPBAS was explored using RRS and conductivity methods, indicating that the gemini surfactant reacting with heparin mainly exists in the form of micellar-type aggregates. A model of the reaction between heparin and DPBAS molecules has been proposed.
Co-reporter:Jiang Xue Dong, Wei Wen, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2012 Volume 86() pp:527-532
Publication Date(Web):February 2012
DOI:10.1016/j.saa.2011.11.004
In pH 2.6 HCl solution, dopamine (DA) could reduce Fe(III) to Fe(II), which further reacted with [Fe(CN)6]3− to form a Fe3[Fe(CN)6]2 complex. By virtue of hydrophobic force and Van der Waals force, the complex aggregated to form Fe3[Fe(CN)6]2 nanoparticles with the average diameter of about 20 nm. This resulted in a significant enhancement of resonance Rayleigh scattering (RRS). The maximum wavelength of the ion-association complex was located at about 350 nm. The increment of scattering intensity (ΔIRRS) was directly proportional to the concentration of DA in the range of 0.06–1.0 μg/mL. This method has high sensitivity and the detection limit (3σ) for DA was 3.43 ng/mL. In this work, the characteristics of absorption and RRS spectra of this reaction have been studied. The optimum reaction condition and influencing factors have been investigated. The method was applied to the determination of DA in pharmaceutical samples with satisfactory results. Furthermore, the reaction mechanism and the reasons of RRS enhancement have been explored.Graphical abstractHighlights► RRS spectra of the dopamine–Fe(III)–[Fe(CN)6]3− system were studied. ► Formation mechanism of Prussian blue nanoparticles produced by dopamine was discussed. ► A novel method to determine dopamine by RRS was established. ► The detection limit of dopamine reached nanogram level.
Co-reporter:Xiao Feng Yang;Nian Bing Li
Luminescence 2012 Volume 27( Issue 3) pp:217-222
Publication Date(Web):
DOI:10.1002/bio.1335
ABSTRACT
A post-chemiluminescence (PCL) phenomenon was observed when chloramphenicol was injected into a mixture of luminol and potassium periodate after the chemiluminescence (CL) reaction of luminol–potassium periodate had finished. The possible reaction mechanism was proposed based on studies of the CL kinetic characteristics, the CL spectra, the fluorescence spectra and the UV-vis absorption spectra of the related substances. Based on the PCL reaction, a rapid and sensitive method for the determination of chloramphenicol was established. The linear response range was 6.0 × 10−7–1.0 × 10−5 mol/L, with a correlation coefficient of 0.9986. The relative standard deviation (RSD) for 5.0 × 10−6 mol/L chloramphenicol was 2.3% (n = 11). The detection limit was 1.6 × 10−7 mol/L. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Wei Tao Huang, Yan Shi, Wan Yi Xie, Hong Qun Luo and Nian Bing Li
Chemical Communications 2011 vol. 47(Issue 27) pp:7800-7802
Publication Date(Web):01 Jun 2011
DOI:10.1039/C1CC11631B
Herein, we demonstrate the first use of a reduced graphene oxide (rGO)–organic dye nanoswitch for the label-free, sensitive and selective detection of Hg2+ using bifunctional rGO as an effective nanoquencher and highly selective nanosorbent. Moreover, a reversible on–off INHIBIT rGO logic gate based on a cysteine–Hg2+ system has also been designed.
Co-reporter:Wan Yi Xie, Wei Tao Huang, Nian Bing Li and Hong Qun Luo
Analyst 2011 vol. 136(Issue 20) pp:4130-4133
Publication Date(Web):24 Aug 2011
DOI:10.1039/C1AN15522A
Upon formation of cytosine–Ag+–cytosine base pairs as a mediator for the photoinduced electron transfer, the fluorescence of FAM-labeled DNA was quenched and the fluorescence emission wavelength exhibited a red shift. Based on these phenomena a novel dual-output fluorescent DNA sensor for Ag+ ions and cysteine detection was developed.
Co-reporter:Chun Hua Qu;Xian Liang Li;Lei Zhang;Cun Xian Xi;Guo Ming Wang
Chromatographia 2011 Volume 73( Issue 3-4) pp:243-249
Publication Date(Web):2011 February
DOI:10.1007/s10337-010-1873-6
An ultra performance liquid chromatography (UPLC) method was established for the simultaneous determination of cimaterol, salbutamol, terbutaline, and ractopamine in feed. Target compounds were extracted with methanol and centrifuged. The supernatant was then transferred and concentrated, and applied to a solid phase extraction MCX cartridge for clean-up before UPLC analysis. The calibration curves for the four β-agonists were good linear in concentration range of 0.05–1.0 μg mL−1 with the correlation coefficients (r) over 0.999. The average recoveries were in the range of 90.1–101.4% with relative standard deviation values lower than 8.0%.
Co-reporter:Jin Fang Liu, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2011 Volume 79(Issue 3) pp:631-637
Publication Date(Web):August 2011
DOI:10.1016/j.saa.2011.03.046
In a weak alkaline Britton–Robinson buffer medium, erythrosine (Ery) can react with Fe(phen)32+ to form 1:1 ion–association complex, which will cause not only the changes of the absorption spectra, but also the remarkable enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) spectra, and the appearance of new spectra of RRS, SOS and FDS. The maximum RRS, SOS and FDS wavelengths (λex/λem) of the ion–association complex are located at 358/358 nm, 290/580 nm and 780/390 nm, respectively. The increments of scattering intensities (ΔI) are directly proportional to the concentration of Ery in a certain range. The detection limits for Ery are 0.028 μg mL−1 for RRS method, 0.068 μg mL−1 for SOS method and 0.11 μg mL−1 for FDS method, respectively. Among them, the RRS method has the highest sensitivity. Based on the above researches, a new highly sensitive and simple method for the determination of Ery has been developed. In this work, the spectral characteristics of absorption, RRS, SOS and FDS spectra, the optimum conditions of the reaction and influencing factors for the RRS, SOS and FDS intensities were investigated. In addition, the reaction mechanism was discussed.Graphical abstractHighlights► RRS, SOS and FDS spectra of the erythrosine-Fe(phen)32+ system were studied. ► Novel methods to determine erythrosine by RRS, SOS and FDS were established. ► The possible mechanism of the interaction was discussed. ► The detection limit of erythrosine reached nanogram level.
Co-reporter:Xiao Yan Jia;Nian Bing Li
Chromatographia 2010 Volume 71( Issue 9-10) pp:839-843
Publication Date(Web):2010 May
DOI:10.1365/s10337-010-1547-4
A new microextraction technique termed reverse dispersive liquid–liquid microextraction (R-DLLME) was developed. An orthogonal array design was used to optimize ultrasonic extraction conditions. In this method, the appropriate ionic liquid was injected into the sample by pipette. The performance of R-DLLME was illustrated with the determination of ursolic acid in force loquat capsule sample by RP-LC-UV detection. The optimized method exhibits a good linearity (r = 0.9989) over the studied range (2.0–60.0 μg mL−1) for ursolic acid. The recovery was 95.9–105.5%. The R-DLLME method has the advantages of simplicity of operation, rapidity, low cost, high recovery and enrichment factor.
Co-reporter:Yan Ma, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2009 Volume 73(Issue 4) pp:747-751
Publication Date(Web):15 August 2009
DOI:10.1016/j.saa.2009.03.013
Three novel methods were designed for the determination of dopamine (DA) by means of the quenching effects on resonance Rayleigh scattering (RRS) and non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities. In Britton–Robinson buffer medium (pH 6.02), I3− could react with DA to produce I−, which resulted in the decreases of the RRS, SOS and FDS intensities of the ethyl violet (EV)–I3− system, and the decreases of scattering intensity (ΔI) were directly proportional to the concentrations of DA in a certain range. The detection limit (3σ) for DA was 0.0195 μmol/L for the RRS method, 0.286 μmol/L for the SOS method and 0.0985 μmol/L for the FDS method, respectively. In this work, the characteristics of absorption, RRS, SOS and FDS spectra of this reaction have been studied; the optimum reaction condition and influencing factors have been investigated. The methods were applied to the determination of DA in pharmaceutical samples with satisfactory results.
Co-reporter:Xiu Li Hao, Nian Bing Li, Hong Qun Luo
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2009 Volume 71(Issue 5) pp:1673-1677
Publication Date(Web):January 2009
DOI:10.1016/j.saa.2008.06.019
A triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method was developed to detect dextran sulfate sodium (DSS) with crystal violet (CV). At pH 10.0 Britton Robinson buffer solution medium, the interaction of CV with DSS occurred which greatly enhanced the RRS intensity with the new RRS peaks appearing at 340, 501 and 671 nm and all these three peaks enhanced with the increase of DSS concentration in the range of 0.04–2.5 μg ml−1 and the detection limit for the three single peaks was 0.024, 0.027, and 0.027 μg ml−1, respectively, whereas that of the TWO-RRS method was 0.013 μg ml−1. The TWO-RRS method was found to have much better flexibility and high sensitivity than the single-wavelength method. In this paper, the interaction conditions were optimized. The affecting factors and characteristics of RRS for the interaction of DSS with CV were investigated and a sensitive method for the determination of trace amounts of DSS using the TWO-RRS method was developed.
Co-reporter:Yun Wu;Nian Bing Li
Microchimica Acta 2008 Volume 160( Issue 1-2) pp:185-190
Publication Date(Web):2008 January
DOI:10.1007/s00604-007-0846-4
2,5-Dimercapto-1,3,4-thiadiazole (DMTD) self-assembled monolayer on gold electrode was prepared and investigated by electrochemical measurement. The DMTD/Au electrode exhibited a significantly increased sensitivity and selectivity for Pb(II) in acetate buffer (pH 5.5) at a potential of −1.0 V (vs Ag/AgCl) for 4 min by anodic stripping voltammetry. The influence of various experimental parameters on the voltammetric response was studied. Under the optimized working conditions, the dependence of the stripping peak current response on concentration of Pb(II) was linear in the range of 1–45 µmol L−1 with a correlation coefficient of 0.9988, and the detection limit was 0.10 µmol L−1. The relative standard deviation of the results was 3.4% for six successive determinations of a 20 µmol L−1 Pb(II) solution. A study of interfering substances was also performed. The method was applied to the determination of Pb(II) in water samples with satisfactory results.
Co-reporter:Yun Wu, Nian Bing Li, Hong Qun Luo
Sensors and Actuators B: Chemical 2008 Volume 133(Issue 2) pp:677-681
Publication Date(Web):12 August 2008
DOI:10.1016/j.snb.2008.04.001
A novel sensor was developed for simultaneous detection of Pb, Cd and Zn, based on the differential pulse anodic stripping response at a bismuth/poly(p-aminobenzene sulfonic acid) (Bi/poly(p-ABSA)) film electrode. This electrode was generated in situ by depositing simultaneously bismuth and the metals by reduction at −1.40 V on the poly(p-ABSA) modified electrode. Compared with the bismuth film electrode, the Bi/poly(p-ABSA) film electrode can yield a larger stripping signal for Pb, Cd and Zn. Under the optimum conditions, a linear response was observed for Cd and Zn in the range from 1.00 to 110.00 μg L−1 and for Pb in the range from 1.00 to 130.00 μg L−1. The detection limits of Pb(II), Cd(II) and Zn(II) were 0.80, 0.63 and 0.62 μg L−1, respectively. Finally this sensor had been applied to the simultaneous determination of Pb(II), Cd(II) and Zn(II) in river water samples and the results were quite corresponding to the value obtained by atomic absorption spectrometry.
Co-reporter:Yu-Wei Wang;Nian-Bing Li ;Hong-Qun Luo
Luminescence 2008 Volume 23( Issue 3) pp:126-131
Publication Date(Web):
DOI:10.1002/bio.1020
Abstract
In weak acidic buffer medium, chitosan binding with an anionic surfactant, such as sodium dodecyl benzene sulphonate (SDBS), sodium lauryl sulphate (SLS) or sodium dodecyl sulphonate (SDS), can result in a significant enhancement of resonance Rayleigh scattering (RRS) intensity. The results showed that under optimum conditions the enhanced RRS intensity is proportional to the concentration of chitosan in the range 0.10–20.0 µg/mL for SDBS, 0.27–15.0 µg/mL for SLS and 0.20–15.0 µg/mL for SDS. Among these, the sensitivity of SDBS is the highest and its detection limit for chitosan is 29 ng/mL, while those of SLS and SDS are 83 and 61 ng/mL, respectively. The method has good selectivity and was applied to the determination of trace amounts of chitosan in practical samples with satisfactory results. Therefore, a simple and convenient method with high sensitivity and selectivity for the determination of chitosan was established. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Hong Qun Luo, Hitoshi Shiku, Ayako Kumagai, Yasufumi Takahashi, Tomoyuki Yasukawa, Tomokazu Matsue
Electrochemistry Communications 2007 Volume 9(Issue 11) pp:2703-2708
Publication Date(Web):November 2007
DOI:10.1016/j.elecom.2007.08.024
Micropatterns of diaphorase (Dp) were fabricated on glass substrates by the microcontact printing (μCP) method and characterized with atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). AFM images of the printed samples revealed that the mean height of the Dp patterns was 3–5 nm, indicating the formation of a monolayer pattern. The Dp molecules on the surface organized themselves into two-dimensional arrays. We used two kinds of inking solutions: Dp–phosphate buffer solution (PBS) (pH 7.0) and Dp–PBS (pH 7.0) with glutaraldehyde (GA, 1% v/v) as a cross-linking reagent. Although the AFM imaging showed high-quality Dp monolayer patterns in both cases, SECM measurements indicated that the enzymatic activity of Dp was almost lost when Dp–PBS with GA was used as the inking solution, whereas clear enzymatic activity was found when Dp–PBS was used.
Co-reporter:Wei Wei Zhu, Nian Bing Li, Hong Qun Luo
Talanta 2007 Volume 72(Issue 5) pp:1733-1737
Publication Date(Web):31 July 2007
DOI:10.1016/j.talanta.2007.04.055
A stannum film electrode has been developed for the simultaneous determination of trace levels of chromium(III) and cadmium(II) by differential pulse anodic stripping voltammetry (DPASV). The stannum film electrode was generated in situ by depositing simultaneously the stannum film and the metals obtained by reduction of Cd(II) and Cr(III) at −1.4 V on a glassy carbon electrode. Then, the reduced products were oxidized by scanning the potential of the electrode from −1.4 to −0.4 V using DPASV. The electrode exhibited well-defined and separated stripping signals for both metals accompanied with a low background contribution. The possible mechanism of this design was proposed. Under the optimized working conditions, the detection limit was 2.0 and 1.1 μg l−1 for Cr(III) and Cd(II) at a deposition time of 3 min. Finally, the stannum film electrode was successfully applied to the determination of Cd(II) in tap water with satisfactory results.
Co-reporter:Jiang Xue Dong, Zhong Feng Gao, Ying Zhang, Bang Lin Li, Nian Bing Li, Hong Qun Luo
Biosensors and Bioelectronics (15 May 2017) Volume 91() pp:
Publication Date(Web):15 May 2017
DOI:10.1016/j.bios.2016.11.062
•The Ag NCs were used as a probe for dissolved ammonia sensor.•The sensor possesses high selectivity based on the HS-SDME principle.•The sensor can meet target detection at sub-mg N L−1 level.•Accuracy and practicality of the sensor have been verified.In this paper, a simple sensor platform is presented for highly selective and sensitive detection of dissolved ammonia in aqueous solutions without pretreatment based on temperature gradient headspace single drop microextraction (HS-SDME) technique, and fluorescence and UV–vis spectrophotometry are utilized with the Ag nanoclusters (Ag NCs) functioned by citrate and glutathione as the probe. The sensing mechanism is based on the volatility of ammonia gas and the active response of Ag NCs to pH change caused by the introduction of ammonia. High pH can make the Ag NCs agglomerate and lead to the obvious decrease of fluorescence intensity and absorbance of Ag NCs solution. Moreover, the presented method exhibits a remarkably high selectivity toward dissolved ammonia over most of inorganic ions and amino acid, and shows a good linear range of 10–350 μM (0.14–4.9 mg N L−1) with a low detection limit of 336 nM (4.70 μg N L−1) at a signal-to-noise ratio of 3. In addition, the practical applications of the sensor have been successfully demonstrated by detecting dissolved ammonia in real samples.
Co-reporter:Ting Liu, Jiang Xue Dong, Shi Gang Liu, Na Li, Shu Min Lin, Yu Zhu Fan, Jing Lie Lei, Hong Qun Luo, Nian Bing Li
Journal of Hazardous Materials (15 January 2017) Volume 322(Part B) pp:430-436
Publication Date(Web):15 January 2017
DOI:10.1016/j.jhazmat.2016.10.034
•The carbon quantum dots (CQDs) synthesized with PEI showed an extraordinary reducibility.•The Ag/CQDs composite was prepared by using CQDs as reducing and stabilizing agent.•A simple Ag/CQDs composite-based dual-signal probe was provided for Hg2+ detection.•The proposed strategy shows a potential for detecting Hg2+ in real water samples.A stable silver nanoparticles/carbon quantum dots (Ag/CQDs) composite was prepared by using CQDs as reducing and stabilizing agent. The CQDs synthesized with polyethyleneimine (PEI) showed an extraordinary reducibility. When Hg2+ was presented in the Ag/CQDs composite solution, a color change from yellow to colorless was observed, accompanied by a shift of surface plasmon resonance (SPR) band and decrease in absorbance of the Ag/CQDs composite. On the basis of the further studies on TEM, XPS and XRD analysis, the possible mechanism is attributed to the formation of a silver-mercury amalgam. Hence, a two dimensional sensing platform for Hg2+ detection was constructed upon the Ag/CQDs composite. Based on the change of absorbance, a good linear relationship was obtained from 0.5 to 50 μM for Hg2+. And the limit of detection for Hg2+ was as low as 85 nM, representing high sensitivity to Hg2+. More importantly, the proposed method also exhibits a good selectivity toward Hg2+ over other metal ions. Besides, this strategy demonstrates practicability for the detection of Hg2+ in real water samples with satisfactory results.Download full-size image
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 20) pp:
Publication Date(Web):
DOI:10.1039/C3AY41055B
The formation of zirconium hexacyanoferrate(II) nanoparticles has been developed as a new resonance Rayleigh scattering (RRS) platform for the sensitive detection of trace amounts of dopamine (DA). The determination mechanism is based on dopamine reacting with hexacyanoferrate(III) ions to produce hexacyanoferrate(II) ions in acidic solution, which further react with zirconium ions to produce zirconium hexacyanoferrate(II) complexes. The zirconium hexacyanoferrate(II) complexes aggregate to form zirconium hexacyanoferrate(II) nanoparticles with an average diameter of about 50 nm. This aggregation can produce a strong RRS signal with the wavelength maximum at about 318 nm. This sensing system presented a good linear relationship between the increment of scattering intensity (ΔIRRS) and the concentration of dopamine in the range of 0.03–1.3 μg mL−1 with a correlation coefficient of 0.9996 and a low detection limit (at a signal-to-noise ratio of 3) of 0.392 ng mL−1. Furthermore, this reaction system has been applied successfully to the detection of DA in a pharmaceutical preparation, and the recoveries were between 100.78% and 104.43%.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 16) pp:
Publication Date(Web):
DOI:10.1039/C4AY00843J
A sensitive and selective biosensor has been developed to detect the hydroxyl radical (˙OH), which was generated through the Fenton reaction. ˙OH could oxidatively damage DNA and cleave it into pieces. Based on this, taking [Ru(NH3)6]3+ as the electrochemical indicator, ˙OH was determined on a gold electrode with self-assembled DNA. The resulting electrochemical biosensor showed a wide linear range of detection from 125 pM to 625 nM with a detection limit of 80 pM and satisfactory selectivity.
Co-reporter:Yan Shi, Hong Qun Luo and Nian Bing Li
Chemical Communications 2013 - vol. 49(Issue 55) pp:NaN6211-6211
Publication Date(Web):2013/05/24
DOI:10.1039/C3CC42140F
The RRS intensities are significantly increased only when a parallel-stranded G-quadruplex is added to Mg2+ solution owing to the formation of G-wires between them, but the others cannot. So, we constructed a new and highly sensitive RRS method to discriminate a parallel-stranded G-quadruplex from DNA with other topologies and structures.
Co-reporter:Wan Yi Xie, Wei Tao Huang, Nian Bing Li and Hong Qun Luo
Chemical Communications 2012 - vol. 48(Issue 1) pp:NaN84-84
Publication Date(Web):2011/11/08
DOI:10.1039/C1CC15449D
In the presence of graphene oxide, upon formation of cytosine–Ag–cytosine the fluorescence wavelength of FAM-labeled DNA exhibited a red shift, and its intensity significantly increased. A novel fluorescent DNA sensor for Ag+ and cysteine detection, and a dual-output fluorescent DNA INHIBIT logic gate are designed.
Co-reporter:Wan Yi Xie, Wei Tao Huang, Jian Rong Zhang, Hong Qun Luo and Nian Bing Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 23) pp:
Publication Date(Web):
DOI:10.1039/C2JM31280H
Co-reporter:Fei Qu, Li Li Dou, Nian Bing Li and Hong Qun Luo
Journal of Materials Chemistry A 2013 - vol. 1(Issue 25) pp:NaN4013-4013
Publication Date(Web):2013/04/25
DOI:10.1039/C3TC30168K
The solvatochromism of metal nanoclusters is still a highly debatable topic. In this work, based on hyperbranched polyethyleneimine (PEI)-encapsulated Ag nanoclusters, we present some interesting results on the chemical environment-responsive fluorescence of Ag nanoclusters in 11 different solvents, which may shed some light on this issue. In water and alcohols, the nanoclusters emit intense blue fluorescence; when they are dispersed in water–tetrahydrofuran (THF) mixtures, the fluorescent color changes from intense blue (in pure water) to intense yellow (in pure THF); when they are dispersed in ethylene glycol monomethyl ether, the fluorescence changes from blue to green over time. However, while the fluorescence emission changes, no obvious band shift is exhibited in the absorption features of Ag nanoclusters. Therefore, the PEI-capped Ag nanoclusters show obvious solvatofluorochromic but not solvatochromic properties. Furthermore, the emission from these clusters can also be tuned from blue to yellow by changing the concentration of the Ag nanoclusters.
Co-reporter:Jing Rong Chen, Xiao Xia Jiao, Hong Qun Luo and Nian Bing Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 6) pp:NaN864-864
Publication Date(Web):2012/12/13
DOI:10.1039/C2TB00267A
Two novel probe-label-free electrochemical aptasensors based on methylene blue (MB)-anchored graphene oxide (GO) amplification were developed for thrombin (TB) and ATP detection, taking advantage of the specific binding affinity of the aptamer towards the target and the different affinities of GO for MB, ssDNA, dsDNA, and G-quadruplex.
Co-reporter:Sheng Tian Huang, Yan Shi, Nian Bing Li and Hong Qun Luo
Chemical Communications 2012 - vol. 48(Issue 5) pp:NaN749-749
Publication Date(Web):2011/11/28
DOI:10.1039/C1CC15959C
We introduce a sensitive, rapid, label-free and general fluorescent method for the determination of tartrazine by competitive binding to reduced graphene oxide (rGO) against fluorescein, and the fluorescence recovery upon fluorescein desorption from rGO provides a quantitative readout for tartrazine, giving a detection limit of 0.53 ng mL−1.
Co-reporter:Wei Tao Huang, Yan Shi, Wan Yi Xie, Hong Qun Luo and Nian Bing Li
Chemical Communications 2011 - vol. 47(Issue 27) pp:NaN7802-7802
Publication Date(Web):2011/06/01
DOI:10.1039/C1CC11631B
Herein, we demonstrate the first use of a reduced graphene oxide (rGO)–organic dye nanoswitch for the label-free, sensitive and selective detection of Hg2+ using bifunctional rGO as an effective nanoquencher and highly selective nanosorbent. Moreover, a reversible on–off INHIBIT rGO logic gate based on a cysteine–Hg2+ system has also been designed.
Co-reporter:Jiang Xue Dong, Zi Li Wang, Yue Yang, Zhong Feng Gao, Bang Lin Li, Hui Hui Jiang, Nian Bing Li and Hong Qun Luo
Journal of Materials Chemistry A 2017 - vol. 5(Issue 4) pp:NaN713-713
Publication Date(Web):2016/12/16
DOI:10.1039/C6TB02449A
Developing probes with good biocompatibility and realizing intracellular detection in living cells are of great significance for biomedicine and life sciences, but remain a challenge presently. In this paper, we describe a rapid and highly selective biosensor for Fe3+ detection in living cells based on the Maillard reaction fluorescent products (MRFPs) of glutathione and ascorbic acid as a probe. Experiments show that the MRFPs are non-cytotoxic and possess excellent biocompatibility. Moreover, the MRFPs show a rapid response and good selectivity towards Fe3+ over other metal ions under physiological pH conditions in vitro. The introduction of Fe3+ can quench the fluorescence of MRFPs, and the fluorescence intensity of system decreases linearly with the increasing concentration of Fe3+ in the range of 0.05–50 μM with the detection limit of 4.6 nM at a signal-to-noise ratio of 3. Moreover, the recognition mechanism has been discussed, which is attributed to the charge transfer from excited-state MRFPs molecules to metal ions. In addition, the MRFPs have been successfully demonstrated to be a good imaging probe for Fe3+ sensing in living cells. This study shows that the biocompatible MRFPs might hold great potential for applications in bioimaging, diagnosis, and therapy of intracellular diseases.
![Methanaminium,N-[4-[[4-(dimethylamino)phenyl][4-(methylphenylamino)-1-naphthalenyl]methylene]-2,5-cyclohexadien-1-ylidene]-N-methyl-,chloride (1:1)](http://img.cochemist.com/ccimg/2200/2185-87-7.png)
![Methanaminium,N-[4-[[4-(dimethylamino)phenyl][4-(methylphenylamino)-1-naphthalenyl]methylene]-2,5-cyclohexadien-1-ylidene]-N-methyl-,chloride (1:1)](http://img.cochemist.com/ccimg/2200/2185-87-7_b.png)
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![Benzenesulfonic acid,4-[2-[4-(dimethylamino)phenyl]diazenyl]-](http://img.cochemist.com/ccimg/600/502-02-3_b.png)
