Co-reporter:Ming-Cong Rong, Ke-Xin Zhang, Yi-Ru Wang, Xi Chen
Chinese Chemical Letters 2017 Volume 28, Issue 5(Volume 28, Issue 5) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.cclet.2016.12.009
Heteroatom doping is an efficient approach to regulate the fluorescence properties of carbon dots. Using aminophenylboronic acid as the raw material, a combustion method was developed for the synthesis of boron, nitrogen-doped carbon dots (B, N-carbon dots). The B, N-carbon dots emitted green fluorescence and displayed high resistance to both photo bleaching and ionic strength. A facile fluorescence sensing approach for Cu2+ was fabricated via static fluorescence quenching. Under optimal conditions, a rapid detection of Cu2+ could be completed in 2 min with a linearity ranging from 1 μmol/L to 25 μmol/L and a detection limit of 0.3 μmol/L. Furthermore, the proposed method showed potential applications for the detection of Cu2+ in natural water samples.Download high-res image (119KB)Download full-size imageNovel green fluorescent B, N-carbon dots were obtained by a combustion method using aminophenylboronic acid as both carbon and nitrogen sources, and a fluorescence approach was developed for Cu2+ detection.
Co-reporter:Qiuhong Yao;Yufeng Feng;Mingcong Rong;Shaogui He
Microchimica Acta 2017 Volume 184( Issue 10) pp:4217-4223
Publication Date(Web):06 September 2017
DOI:10.1007/s00604-017-2496-5
Fluorescent boron nitride quantum dots (BNQDs) were synthesized from boric acid and ammonium hydroxide by a hydrothermal method. Under 305 nm excitation, the BNQDs emit blue fluorescence with a peak at 400 nm and a quantum yield of 32%. The BNQDs are highly photostable and resistant to ionic strength. A rapid fluorometric method for the determination of Ni2+ was developed using the heavy-metal free BNQDs via photo-induced electron transfer. Under optimal conditions, fluorescence varies linearly with the logarithm of the Ni2+ concentration in the range from 0.1 to 100 μmol·L−1. The detection limit is 0.1 μmol·L−1.
Co-reporter:Qiuhong Yao, Sisi Lu, Fangyuan Lin, Tingting Zhao, Li Zhao, Xi Chen
Sensors and Actuators B: Chemical 2017 Volume 250(Volume 250) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.snb.2017.04.097
•A core-shell ratiometric pH nanosensor was developed through a facile co-precipitation strategy.•The nanosensors exhibited an excellent ratiometric luminescence response to pH.•The prepared nanosensors could be spontaneously introduced into cytoplasm for RGB intracellular imaging after co-incubation with cells.A core-shell ratiometric pH nanosensor for intracellular imaging was made using a facile co-precipitation strategy. Fluorescein isothiocyanate (FITC), a pH sensitive probe with green fluorescence emission, was first conjugated to amino-terminated polystyrene (PS-NH2). In the co-precipitation method, the FITC-PS-NH2, polystyrene, amphiphilic poly(styrene-co-maleic anhydride) and the reference fluorochrome, 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin, were used to form nanosize hydrophobic cores in an aqueous phase. Finally, poly-l-lysine was selected and attached to the cores through electrostatic forces to improve the cytoplasmic compatibility of the nanoparticles. The prepared FITC doped polymer nanoparticles exhibited excellent ratiometric luminescence responses to pH change and had exceptional intracellular imaging performance as well. Using the prepared nanosensors, a sensing approach for the semi-quantitative pH detection of living cells was set up, revealing the potential applications in biological and biomedical pH detection.
Co-reporter:Zhixiong Cai, Wei Xu, Feiming Li, Qiuhong Yao, and Xi Chen
ACS Sustainable Chemistry & Engineering 2017 Volume 5(Issue 1) pp:
Publication Date(Web):December 5, 2016
DOI:10.1021/acssuschemeng.6b01952
The development of high-performance nonprecious electrocatalysts toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for overall water splitting but remains a grand challenge. In this study, Co phosphate (CP) nanoparticles encapsulated in three-dimensional porous N,P-codoped carbon networks (NPC) were fabricated by direct growth on carbon cloth (CC), which were further used as an integrated three-dimensional (3D) electrode for cost-effective and energy efficient HER and OER both in acid and alkaline medium. Impressively, the as-obtained flexible integrated electrode exhibited excellent activities and robust stability, due to the unique 3D architecture with improved electron transport capability, high number of active sites, and channels for reactant/product transfer. Our experimental results show significantly enhanced performance for such engineered nanostructures due to the synergistic effect from nanoparticles encapsulation and nitrogen and phosphorus doping on carbon structures. Such an versatile electrode can serve as a bifunctional catalyst for overall water splitting with excellent catalytic performance and durability in a more direct and simple way, which reduces the production cost of practical technological devices. The new design demonstrated here opened avenues for simple, low-cost, and scalable manufacture of high performance bifunctional catalysts for renewable energy technologies.Keywords: 3D electrode; Carbon encapsulated; Co phosphate; Electrochemical water splitting; N,P-codoped carbon;
Co-reporter:Wei Xu, Sisi Lu, Mengxi Xu, Yaqi Jiang, Yiru Wang and Xi Chen
Journal of Materials Chemistry A 2016 vol. 4(Issue 2) pp:292-298
Publication Date(Web):23 Nov 2015
DOI:10.1039/C5TB02071A
We developed novel functionalized semiconducting polymer dots (Pdots) for the simultaneous imaging of intracellular pH and oxygen. The Pdots comprised a semiconducting polymer of poly[9,9-dioctylfluorenyl-2,7-diyl] (PFO), amino terminated polystyrene, fluorescein isothiocyanate (FITC) as a pH sensitive dye, and Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) as an oxygen sensitive dye. In the sensing Pdots, PFO was used as a donor for Förster resonance energy transfer. The emission wavelengths of the PFO, FITC and PtTFPP matched the three color channel of the red, green and blue chip, which offered great advantage for dual sensing using conventional fluorescence microscopy. The nanosensor was taken up by cells via endocytosis, and exhibited high brightness, small particle size, triple color under a single excitation, a large two-photon absorbance cross-section and low-toxicity to cells. These salient features demonstrated the potential utility of the Pdots for dual pH and O2 imaging in cells.
Co-reporter:Xiaomei Chen, Rongrong Wu, Lechang Sun, Qiuhong Yao, Xi Chen
Journal of Electroanalytical Chemistry 2016 Volume 781() pp:310-314
Publication Date(Web):15 November 2016
DOI:10.1016/j.jelechem.2016.07.011
•A highly sensitive ECL sensor for CBT detection is developed.•PtNPs are reduced on the surface of RuSiNPs by a mild reagent-ethanol.•The sensitivity was improved for the good conductivity and clean surface of PtNPs.•Strong binding effect of [Ru(bpy)3]2 + in RuSiNPs benefit the stability of the sensor.In this work, a highly sensitive electrochemiluminescence (ECL) sensor for the detection of clenbuterol (CBT) in pork is reported. The fabrication of the sensor was carried out by modification of a glassy carbon electrode (GCE) with platinum nanoparticles (PtNPs)/silica nanoparticles doped with [Ru(bpy)3]2 + (RuSiNPs)/Nafion composite. The morphology, composition and electrochemical behavior of the PtNPs/RuSiNPs were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and electrochemical impedance spectroscopy, respectively. It was found that all the PtNPs are formed on the surface of RuSiNPs and the electron transfer resistance was obviously reduced on the PtNPs/RuSiNPs GCE. Taking the advantage of the Si-O-Si grid of RuSiNPs, the [Ru(bpy)3]2 + luminophore leaching from the modified electrode could largely be prevented, benefiting the ECL signal stability. Moreover, due to the enhanced electron transfer rate and electrocatalytical property of the PtNPs, the sensitivity of the PtNPs/RuSiNPs-based sensor was greatly improved. Under optimized conditions, the ECL peak intensity was linear with the concentration of CBT in the range of 5–100 ng mL− 1, with a detection limit as low as 0.8 ng mL− 1. The recoveries of the CBT obtained from spiked pork samples at PtNPs/RuSiNPs/Nafion GCE were between 89.5% and 106.3% and the RSDs were lower than 6.21%. The proposed ECL sensor based on PtNPs/RuSiNPs composite presented good characteristics for CBT determination in terms of rapid, high sensitivity and good stability, promising the applicability of this sensor in real samples.
Co-reporter:Sisi Lu, Wei Xu, Yiying Chen, Yaqi Jiang, Qiuhong Yao, Feng Luo, Yiru Wang, Xi Chen
Sensors and Actuators B: Chemical 2016 Volume 232() pp:585-594
Publication Date(Web):September 2016
DOI:10.1016/j.snb.2016.04.007
A new methodology to obtain honeycomb-like oxygen-sensitive polystyrene nanospheres has been developed via a facile co-precipitation procedure. Commercially available triblock copolymer Pluronic F127 was utilized as a soft template to shape polystyrene into regular spherical nanostructures. The morphology of the prepared polystyrene nanospheres could be tuned through the modification of the initial concentration of F127 or polystyrene in the aqueous phase. The oxygen indicator, platinum(II)-tetrakis(pentafluorophenyl)porphyrin (maximal emission wavelength at 648 nm), and the reference fluorophore, poly(9, 9-dioctylfluorene) (maximal emission wavelength at 440 nm), were selected and doped into the polystyrene nanospheres for the ratiometric detection of oxygen. The honeycomb-like oxygen-sensitive polystyrene nanospheres exhibited satisfactory ratiometric luminescence responses to O2 with high quenching efficiency and full reversibility in oxygen sensing. More importantly, the as-prepared polystyrene nanospheres displayed distinct change from red to blue when they were exposed to air from a nitrogen atmosphere. These prepared polystyrene nanospheres can potentially be used as anti-counterfeit labels in the recognition of forged items, or acted as a dynamic signage for on shelf food packaging, since many foods are kept in a vacuum or in an inert gas, such as carbon dioxide or nitrogen.
Co-reporter:Tingting Zhao, Chunshui Lin, Qiuhong Yao, Xi Chen
Talanta 2016 Volume 154() pp:492-497
Publication Date(Web):1 July 2016
DOI:10.1016/j.talanta.2016.03.091
•This work was the first to report ECL detection of ATP based on ATP-dependent enzyme reaction.•It involves no conformational change but only the preference of Exo III activity with and without ATP.•It is sensitive and selective by coupling enzyme amplification and ECL technique.In this work, we describe a new label-free, sensitive and highly selective strategy for the electrochemiluminescent (ECL) detection of ATP at the picomolar level via ATP-induced ligation. The molecular-beacon like DNA probes (P12 complex) are self-assembled on a gold electrode. The presence of ATP leads to the ligation of P12 complex which blocks the digestion by Exonuclease III (Exo III). The protected P12 complex causes the intercalation of numerous ECL indicators (Ru(phen)32+) into the duplex DNA grooves, resulting in significantly amplified ECL signal output. Since the ligating site of T4 DNA ligase and the nicking site of Exo III are the same, it involves no long time of incubation for conformation change. The proposed strategy combines the amplification power of enzyme and the inherent high sensitivity of the ECL technique and enables picomolar detection of ATP. The developed strategy also shows high selectivity against ATP analogs, which makes our new label-free and highly sensitive ligation-based method a useful addition to the amplified ATP detection arena.In the highly sensitive and selective ECL detection of ATP through T4 ligase and Exo III-based enzyme amplification, T4 ligase showed specific dependence on its cofactor ATP to induce the ligation while the ligation inhibited digestion by Exo III. As illustrated in Scheme 1, the protocol proposed for ATP monitoring involved the self-assembly of P1 and P2 via the formation of an Au-S bond, surface blocking with MCH, a ligation and digestion step with and without ATP, intercalation of Ru(phen)32+and ECL measurements of the resulting modified electrode. No ligation occurred in the absence of ATP, which resulted in the digestion of P2 by Exo III. The weak interaction between the ECL indicator, Ru(phen)32+, and the digested P2 caused a considerably low ECL background signal. Whereas, when ATP appeared in the system, T4 ligase took ATP as a cofactor, and catalyzed the ligation between the 5′ PO4-minus of P1 and 3′ OH-minus of P2, thus, successfully blocking the digestion by Exo III. In the above process, ATP was expected to efficiently trigger the ligation and keep the duplex DNA biding sites for the successful intercalation of Ru(phen)32+, and thus lead to a substantial increase in the corresponding ECL intensity. The ECL signal from the intercalated Ru(phen)32+with TPrA as a coreactant was related to the quantity of ATP in the testing buffer and served as the quantitative signal for the ATP determination.
Co-reporter:Zhi-Xiong Cai, Xin-Hong Song, Yi-Ying Chen, Yi-Ru Wang, Xi Chen
Sensors and Actuators B: Chemical 2016 Volume 222() pp:567-573
Publication Date(Web):January 2016
DOI:10.1016/j.snb.2015.08.094
•A novel 3D nitrogen (N) doped graphene aerogel (GA) was used as a direct electrode for electrochemical sensing.•Owing to the 3D open-pore structure and nitrogen doping property, the sensor showed excellent electrocatalytic activity towards H2O2 reduction.•The proposed non-enzymatic sensor was applied for H2O2 detection.A facile, template-free and low-cost strategy has been developed to construct a 3D nitrogen (N) doped graphene aerogel (GA) by the incorporation of dopamine (DA). 3D-NGA can be served as a highly efficient electrocatalyst in the reduction of H2O2, which is then applied in the nonenzymatically electrochemical determination of H2O2. The structure and morphology of hollow 3D-NGA were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrocatalytic activity of 3D-NGA was investigated by cyclic voltammetry (CV) and chronoamperometry, exhibiting a direct for the reduction of H2O2 at −0.5 V. This constructing sensor was applied in detection of H2O2 with a detection limit of 0.05 mM, a linear detection range from 0.2 to 35 mM. Due to superior catalytic performance and low cost of 3D-NGA electrode, it shows great potential in applications for direct sensing of H2O2.
Co-reporter:Zhixiong Cai, Feiming Li, Wei Xu, Yaqi Jiang, Feng Luo, Yiru Wang, Xi Chen
Nano Energy 2016 Volume 26() pp:257-266
Publication Date(Web):August 2016
DOI:10.1016/j.nanoen.2016.05.039
•An integrated 3D hierarchical nanostructure was applied as a photoanode.•The novel structure combined the advantages of 1D nanowire and 2D nanosheet.•PEC reaction is enhanced by multiple functional components of 3D nanostructures.The most important factors dominating photoelectrochemical (PEC) water splitting performance include light absorption, charge separation and transport, and surface chemical reactions. In order to meet these factors, a novel FexNi1−xO/Bi2MoO6/Si nanowire hierarchical nanostructure was produced using a metal-assisted chemical-etching and hydrothermal growth process, in which Si nanowires were used as backbones, Bi2MoO6 nanosheets as coating, and FexNi1−xO nanoparticles (NPs) as surface catalysts. This integrated three-dimensional (3D) hierarchical nanostructure was applied as a photoanode in a PEC water reaction, and higher photostability and photocurrent density were gained. The excellent PEC performance was due to the 3D hierarchically structural effect, resulting in the enhancement of the surface-to-volume ratio, light harvest and high speed electron transport, and at the same time, terminal FexNi1−xO NPs played the role of the surface catalyst effectively in order to accelerate the water splitting reaction and enhance photostability. Based on such an environmentally friendly hierarchical nanostructure, the study provided an efficient route to improve water-splitting performance and it could also be a model structure for similar electrode materials.
Co-reporter:Sisi Lu, Wei Xu, Jinliang Zhang, Yiying Chen, Lei Xie, Qiuhong Yao, Yaqi Jiang, Yiru Wang, Xi Chen
Biosensors and Bioelectronics 2016 Volume 86() pp:176-184
Publication Date(Web):15 December 2016
DOI:10.1016/j.bios.2016.06.050
•A new type of ratiometric oxygen nanosensor was prepared via a simple co-precipitation method.•The prepared core-shell nanosensors exhibited an excellent response to O2 content.•The nanosensors could permeate into living cells after co-incubation.A new type of cell-penetrating ratiometric fluorescence oxygen sensing nanoparticle was prepared through a facile co-precipitation method. Amphiphilic polymer poly (styrene-co-maleic anhydride) (PSMA) was firstly cooperated with polystyrene (PS) to envelop the highly photostable phosphorescent oxygen indicator, platinum(II)-tetrakis(pentafluorophenyl)porphyrin (PtTFPP, emission at 648 nm), and the reference fluorophore, poly(9, 9-dioctylfluorene) (PFO, emission at 440 nm ), via hydrophobic interaction in aqueous solution. To improve the sensor biocompatibility, the biomacromolecule poly-l-lysine (PLL) was selected to act as a shell via electrostatic forces. The as-prepared PtTFPP doped core-shell nanoparticles (called PPMA/PLL NPs) exhibited an excellent ratiometric luminescence response to O2 content with high quenching efficiency and full reversibility in the oxygen sensing. More importantly, these oxygen nanosensors passed across the cell membrane after co-incubation without external force. Labeled cells exhibited high brightness in the matching blue and red channels of a digital camera. And most nanosensors were found locating in cytoplasm rather than being trapped in endosomes.
Co-reporter:Xuexu Chen, Chunshui Lin, Yiying Chen, Feng Luo, Yiru Wang, Xi Chen
Biosensors and Bioelectronics 2016 Volume 83() pp:97-101
Publication Date(Web):15 September 2016
DOI:10.1016/j.bios.2016.04.038
•We proposed a simple and fast fluorescence method to detect proteins by loop DNA.•The DNA can form a self-complementary structure with two stem-loop structures.•The target protein can bind to biotin protecting DNA from cleavage by exonuclease.•The DNA sequence could be randomly coded with part self-hybridization.•This method is a signal off-on fluorescent strategy.A novel label-free turn-on fluorescence biosensor for the determination of streptavidin (SA) was proposed. Using terminal protection of small molecule-linked DNA chimeras, which can protect DNA from degradation by various exonucleases when the small molecule moieties are bound to their protein target, we designed a loop probe, where the 3′-end was modified with biotin to resist digestion by exonucleases in the presence of target SA. Coupled with an intercalating dye, SYBR Green I, strong enhancement of the fluorescence signals was obtained compared with that in the absence of SA. A linear correlation equation was obtained for SA from 0 to 200 nM with a limit detection of 0.4 nM. This strategy holds great promise for practical applications with good specificity and sensitivity.
Co-reporter:Xinhong Song;Yiying Chen;Mingcong Rong;Dr. Zhaoxiong Xie;Tingting Zhao; Yiru Wang;Dr. Xi Chen;Dr. Otto S. Wolfbeis
Angewandte Chemie International Edition 2016 Volume 55( Issue 12) pp:3936-3941
Publication Date(Web):
DOI:10.1002/anie.201511064
Abstract
Surfaces with super-amphiphilicity have attracted tremendous interest for fundamental and applied research owing to their special affinity to both oil and water. It is generally believed that 3D graphenes are monoliths with strongly hydrophobic surfaces. Herein, we demonstrate the preparation of a 3D super-amphiphilic (that is, highly hydrophilic and oleophilic) graphene-based assembly in a single-step using phytic acid acting as both a gelator and as a dopant. The product shows both hydrophilic and oleophilic intelligence, and this overcomes the drawbacks of presently known hydrophobic 3D graphene assemblies. It can absorb water and oils alike. The utility of the new material was demonstrated by designing a heterogeneous catalytic system through incorporation of a zeolite into its amphiphilic 3D scaffold. The resulting bulk network was shown to enable efficient epoxidation of alkenes without prior addition of a co-solvent or stirring. This catalyst also can be recovered and re-used, thereby providing a clean catalytic process with simplified work-up.
Co-reporter:Xinhong Song;Yiying Chen;Mingcong Rong;Dr. Zhaoxiong Xie;Tingting Zhao; Yiru Wang;Dr. Xi Chen;Dr. Otto S. Wolfbeis
Angewandte Chemie 2016 Volume 128( Issue 12) pp:4004-4009
Publication Date(Web):
DOI:10.1002/ange.201511064
Abstract
Surfaces with super-amphiphilicity have attracted tremendous interest for fundamental and applied research owing to their special affinity to both oil and water. It is generally believed that 3D graphenes are monoliths with strongly hydrophobic surfaces. Herein, we demonstrate the preparation of a 3D super-amphiphilic (that is, highly hydrophilic and oleophilic) graphene-based assembly in a single-step using phytic acid acting as both a gelator and as a dopant. The product shows both hydrophilic and oleophilic intelligence, and this overcomes the drawbacks of presently known hydrophobic 3D graphene assemblies. It can absorb water and oils alike. The utility of the new material was demonstrated by designing a heterogeneous catalytic system through incorporation of a zeolite into its amphiphilic 3D scaffold. The resulting bulk network was shown to enable efficient epoxidation of alkenes without prior addition of a co-solvent or stirring. This catalyst also can be recovered and re-used, thereby providing a clean catalytic process with simplified work-up.
Co-reporter:Dr. Mingcong Rong;Dr. Zhixiong Cai;Dr. Lei Xie;Dr. Chunshui Lin;Dr. Xinhong Song;Dr. Feng Luo;Dr. Yiru Wang; Xi Chen
Chemistry - A European Journal 2016 Volume 22( Issue 27) pp:9387-9395
Publication Date(Web):
DOI:10.1002/chem.201601065
Abstract
Graphitic carbon nitride nanodots (g-C3N4 nanodots), as a new kind of heavy-metal-free quantum dots, have attracted considerable attention because of their unique physical and chemical properties. Although various methods to obtain g-C3N4 nanodots have been reported, it is still a challenge to synthesize g-C3N4 nanodots with ultrahigh fluorescence quantum yield (QY). In this study, highly fluorescent phosphorus/oxygen-doped graphitic carbon nitride (P,O-g-C3N4) nanodots were prepared by chemical oxidation and hydrothermal etching of bulk P-g-C3N4 derived from the pyrolysis of phytic acid and melamine. The as-prepared P,O-g-C3N4 nanodots showed strong blue fluorescence and a relatively high QY of up to 90.2 %, which can be ascribed to intrinsic phosphorus/oxygen-containing groups, and surface-oxidation-related fluorescence enhancement. In addition, the P,O-g-C3N4 nanodots were explored for cell imaging with excellent stability and biocompatibility, which suggest that they have great potential in biological applications.
Co-reporter:Chunhua Ma, Chunshui Lin, Yiru Wang, Xi Chen
TrAC Trends in Analytical Chemistry 2016 Volume 77() pp:226-241
Publication Date(Web):March 2016
DOI:10.1016/j.trac.2016.01.013
•The studies of signaling of ATP-binding aptamer are presented.•The recent advances in DNA-based ATP sensors are summarized.•The applications of DNA-based ATP sensors in living cells are also summarized and commented.The detection of ATP is of great value due to its role in the regulation and integration of cellular metabolism. DNA has been developed as a promising recognition element in ATP sensing, among which ATP-binding aptamer (ABA) exhibits many advantages in terms of the simplicity of synthesis, ease of labeling and excellent stability. Moreover, progress in the development of nanomaterials and enzyme amplification provides ABA even more flexibility as an ATP recognition tool in the fields of fluorescence, electrochemistry and colorimetric. In addition to ABA, ATP dependent enzyme reaction (ATP-DER, T4 DNA ligase) using DNA as a substrate has been developed for ATP sensing with high sensitivity and selectivity. In this review, we summarize the recent advances in DNA-based ATP sensors and their applications in living cells, and also discuss their future development.
Co-reporter:Mingcong Rong, Xinhong Song, Tingting Zhao, Qiuhong Yao, Yiru Wang and Xi Chen
Journal of Materials Chemistry A 2015 vol. 3(Issue 41) pp:10916-10924
Publication Date(Web):17 Sep 2015
DOI:10.1039/C5TC02584B
Highly fluorescent phosphorus, oxygen-doped graphitic carbon nitride nanodots (P,O-g-C3N4 nanodots) were synthesized using chemical oxidation and hydrothermal etching of bulk P-g-C3N4 obtained via pyrolysis of phytic acid and melamine. The P,O-g-C3N4 nanodots emitted strong blue fluorescence with a high quantum yield of 90.2%, and displayed high resistance to photobleaching and high ionic strength. A sensitive and facile fluorescence sensing approach for Cu2+ was developed through fluorescence quenching based on the static fluorescence quenching and photoinduced electron transfer. Under optimal conditions, a rapid detection of Cu2+ could be completed in 5 min with a detection limit of 2 nM, and a linearity ranging from 0 to 1 μM. Using acetylthiocholine (ATCh) as the substrate, the fluorescence of the P,O-g-C3N4 nanodots–Cu2+ system could be sensitively turned on in the presence of acetylcholinesterase (AChE) through the reaction between Cu2+ and thiocholine, the hydrolysis product of ATCh by AChE. A linearity ranging from 0.01 to 3 mU mL−1 could be obtained with a detection limit of 0.01 mU mL−1. In addition, the proposed approach showed potential application for the detection of Cu2+ in natural water samples and AChE activity in human plasma.
Co-reporter:Liping Lin, Xinhong Song, Yiying Chen, Mingcong Rong, Tingting Zhao, Yaqi Jiang, Yiru Wang and Xi Chen
Nanoscale 2015 vol. 7(Issue 37) pp:15427-15433
Publication Date(Web):20 Aug 2015
DOI:10.1039/C5NR04005A
Highly fluorescent nitrogen-doped graphene quantum dots (N-GQDs) with greenish-yellow emission and quantum yield of 13.2% have been synthesized via a one-pot hydrothermal method. The obtained N-GQDs displayed excellent optical properties, high photostability and resistance to strong ion strength. Based on the higher affinity of pyrophosphate (PPi) than carboxyl and amido groups on the surface of the N-GQDs to Eu3+, a Eu3+-modulated N-GQD off–on fluorescent probe for PPi detection was constructed with a detection limit of 0.074 μM. The detection process was simple in design, easy to operate, and showed a highly selective response to PPi in the presence of co-existing anions. This work widens the applications of N-GQDs with versatile functionality and reactivity in clinical diagnostics and as biosensors.
Co-reporter:Liping Lin, Mingcong Rong, Sisi Lu, Xinhong Song, Yunxin Zhong, Jiawei Yan, Yiru Wang and Xi Chen
Nanoscale 2015 vol. 7(Issue 5) pp:1872-1878
Publication Date(Web):03 Dec 2014
DOI:10.1039/C4NR06365A
A facile bottom-up method for the synthesis of highly fluorescent nitrogen-doped graphene quantum dots (N-GQDs) has been developed via a one-step pyrolysis of citric acid and tris(hydroxymethyl)aminomethane. The obtained N-GQDs emitted strong blue fluorescence under 365 nm UV light excitation with a high quantum yield of 59.2%. They displayed excitation-independent behavior, high resistance to photobleaching and high ionic strength. In addition to the good linear relationship between the fluorescence intensity of the N-GQDs and pH in the range 2–7, the fluorescence intensity of the N-GQDs could be greatly quenched by the addition of a small amount of 2,4,6-trinitrophenol (TNP). A sensitive approach has been developed for the detection of TNP with a detection limit of 0.30 μM, and a linearity ranging from 1 to 60 μM TNP could be obtained. The approach was highly selective and suitable for TNP analysis in natural water samples.
Co-reporter:Zhuo Deng, Xuexu Chen, Yiru Wang, Enhua Fang, Zhigang Zhang, and Xi Chen
Analytical Chemistry 2015 Volume 87(Issue 1) pp:633
Publication Date(Web):November 21, 2014
DOI:10.1021/ac503341g
By coupling thin-film microextraction (TFME) with surface-enhanced Raman scattering (SERS), a facile method was developed for the determination of sulfur dioxide (SO2), the most effective food additive in winemaking technology. The TFME substrate was made by free settling of sea urchin-like ZnO nanomaterials on a glass sheet. The headspace sampling (HS) procedure for SO2 was performed in a simple homemade device, and then the SO2 was determined using SERS after uniformly dropping or spraying a SERS-active substrate (gold nanoparticles, AuNPs) onto the surface of the TFME substrate. A reproducible and strong SERS response of the SO2 absorbed onto the ZnO substrate was obtained. After condition optimization, the SERS signal intensity at a shift of 600 cm–1 and the SO2 concentration showed a good linearity in the range of 1–200 μg/mL, and the linear correlation coefficient was 0.992. The detection limit for SO2 was found to be 0.1 μg/mL. The HS–TFME–SERS method was applied for the determination of SO2 in wine, and the results obtained agreed very well with those obtained using the traditional distillation and titration method. Analysis of variance and Student t test show that there is no significant difference between the two methods, indicating that the newly developed method is fast, convenient, sensitive and has selective characteristics in the determination of SO2 in wine.
Co-reporter:Mingcong Rong, Liping Lin, Xinhong Song, Tingting Zhao, Yunxin Zhong, Jiawei Yan, Yiru Wang, and Xi Chen
Analytical Chemistry 2015 Volume 87(Issue 2) pp:1288
Publication Date(Web):December 17, 2014
DOI:10.1021/ac5039913
An effective and facile fluorescence sensing approach for the determination of 2,4,6-trinitrophenol (TNP) using the chemically oxidized and liquid exfoliated graphitic carbon nitride (g-C3N4) nanosheets was developed. The strong inner filter effect and molecular interactions (electrostatic, π–π, and hydrogen bonding interactions) between TNP and the g-C3N4 nanosheets led to the fluorescence quenching of the g-C3N4 nanosheets with efficient selectivity and sensitivity. Under optimal conditions, the limit of detection for TNP was found to be 8.2 nM. The proposed approach has potential application for visual detection of TNP in natural water samples for public safety and security.
Co-reporter:Liping Lin, Xinhong Song, Yiying Chen, Mingcong Rong, Tingting Zhao, Yiru Wang, Yaqi Jiang, Xi Chen
Analytica Chimica Acta 2015 Volume 869() pp:89-95
Publication Date(Web):15 April 2015
DOI:10.1016/j.aca.2015.02.024
•The highly intrinsic peroxidase-like catalytic activity of N-GQDs is revealed.•The activity of N-GQDs depended on pH, temperature and H2O2 concentration.•The activity of N-GQDs has been used to the detection of H2O2 and glucose.•This assay was suitable for the detection of glucose concentrations in real samples.In this paper, the highly intrinsic peroxidase-like catalytic activity of nitrogen-doped graphene quantum dots (N-GQDs) is revealed. This activity was greatly dependent on pH, temperature and H2O2 concentration. The experimental results showed that the stable N-GQDs could be used for the detection of H2O2 and glucose over a wide range of pH and temperature, offering a simple, highly selective and sensitive approach for their colorimetric sensing. The linearity between the analyte concentration and absorption ranged from 20 to 1170 μM for H2O2 and 25 to 375 μM for glucose with a detection limit of 5.3 μM for H2O2 and 16 μM for glucose. This assay was also successfully applied to the detection of glucose concentrations in diluted serum and fruit juice samples.
Co-reporter:Liping Lin, Xinhong Song, Yiying Chen, Mingcong Rong, Yiru Wang, Li Zhao, Tingting Zhao, Xi Chen
Analytica Chimica Acta 2015 Volume 891() pp:261-268
Publication Date(Web):3 September 2015
DOI:10.1016/j.aca.2015.08.011
•The europium-decorated graphene quantum dots (Eu-GQDs) have been successfully prepared.•Various characterizations results proved that Eu atoms were successfully introduced into graphene quantum dots.•The introduced Eu atoms changed the electron density and surface chemical activities of Eu-GQDs.•Eu-GQDs were used as an “off-on” fluorescent probe for Cu2+ and l-cysteine detection.•The proposed probe displayed high sensitivity and selectivity and promised application in biological samples.In this work, europium-decorated graphene quantum dots (Eu-GQDs) were prepared by treating three-dimensional Eu-decorated graphene (3D Eu-graphene) via a strong acid treatment. Various characterizations revealed that Eu atoms were successfully complexed with the oxygen functional groups on the surface of graphene quantum dots (GQDs) with the atomic ratio of 2.54%. Compared with Eu free GQDs, the introduction of Eu atoms enhanced the electron density and improved the surface chemical activities of Eu-GQDs. Therefore, the obtained Eu-GQDs were used as a novel “off-on” fluorescent probe for the label-free determination of Cu2+ and l-cysteine (L-Cys) with high sensitivity and selectivity. The fluorescence intensity of Eu-GQDs was quenched in the presence of Cu2+ owing to the coordination reaction between Cu2+ and carboxyl groups on the surface of the Eu-GQDs. The fluorescence intensity of Eu-GQDs recovered with the subsequent addition of L-Cys because of the strong affinity of Cu2+ to L-Cys via the Cu–S bond. The experimental results showed that the fluorescence variation of the proposed approach had a good linear relationship in the range of 0.1–10 μM for Cu2+ and 0.5–50 μM for L-Cys with corresponding detection limits of 0.056 μM for Cu2+ and 0.31 μM for L-Cys. The current approach also displayed a special response to Cu2+ and L-Cys over the other co-existing metal ions and amino acids, and the results obtained from buffer-diluted serum samples suggested its applicability in biological samples.
Co-reporter:Zhixiong Cai, Mingcong Rong, Tingting Zhao, Li Zhao, Yiru Wang, Xi Chen
Journal of Electroanalytical Chemistry 2015 Volume 759(Part 1) pp:32-37
Publication Date(Web):15 December 2015
DOI:10.1016/j.jelechem.2015.08.037
•A novel nanomaterial for PEC was fabricated by the combination of graphene, g-C3N4 and TiO2.•A sensitive PEC sensor was developed for the detection of dopamine.•The linear range of the DA concentration was from 0.1 to 50 μM.A novel photoelectrochemical (PEC) sensing platform is fabricated using the composition of graphitic carbon nitride (g-C3N4), TiO2 nanoparticles (TiO2 NPs) and graphene (G) on an indium tin oxide (ITO) electrode. The graphene layer is acting as the supporter for g-C3N4 to form tightly G-C3N4 thin nanosheets, and behaves as an electron transfer medium to enhance the electron transport ability. Then, TiO2 NPs tightly anchor onto the G-C3N4 nanosheets to form G-C3N4/TiO2 nanocomposite. The photocurrent of G-C3N4/TiO2 drastically enhances compared to G-C3N4 and G-TiO2, which is attributed to the life improvement of the electron–hole pairs and the synergistic amplification between TiO2 NPs and C3N4. Interestingly, the photocurrent of G-C3N4/TiO2 nanocomposite is notably improved upon the addition of dopamine (DA). Based on the enhanced photocurrent signal, a PEC methodology for ultrasensitive determination of DA has been developed, which showed linearly enhanced photocurrent by increasing the DA concentration from 0.1 to 50 μM with a detection limit of 0.02 μM (S/N = 3) under optimized conditions. Therefore, the fabricated photoelectrochemical sensor provides a promising method in the sensing of biomolecules and extended the applications of C3N4-based nanocomposite in the field of PEC sensing.
Co-reporter:Chun-Hua Ma, Jing Zhang, Yong-Cong Hong, Yi-Ru Wang, Xi Chen
Chinese Chemical Letters 2015 Volume 26(Issue 12) pp:1455-1459
Publication Date(Web):December 2015
DOI:10.1016/j.cclet.2015.10.015
Surface-enhanced Raman scattering (SERS) is applied to detect the concentration of carbendzim (CBZ) in tea leaves. Au colloid is selected and used for active surfaces, and the extraction conditions are optimized in the experiment. The linearity range for the SERS intensity and the concentration of CBZ is found to be 0.5 to 8 mg kg−1. The detection limit for CBZ is 0.1 mg kg−1 and its recovery in tea samples is 72.3%. The detection results for CBZ using this method are compared with those of HPLC, and no obvious difference can be found. In addition, by dripping the condensed Au colloid on the tea leaves, the proposed SERS approach could be used to the in-situ determination of the half life period of CBZ on tea leaves.Surface-enhanced Raman scattering (SERS) is applied to detect the concentration of carbendzim (CBZ) in tea leaves.
Co-reporter:Zhuo Deng, Haihong Liu, Yiru Wang and Xi Chen
Analytical Methods 2015 vol. 7(Issue 5) pp:2190-2195
Publication Date(Web):23 Jan 2015
DOI:10.1039/C4AY02057J
A novel technique combining solid-phase extraction and surface-enhanced Raman spectroscopy has been developed using a home-made test strip as the solid phase apparatus and detecting platform for surface-enhanced Raman spectroscopy. Single wall carbon nanotubes (SWCNTs) were functionalized with oxidizing acid and deposited on a filter membrane to fabricate the SWCNTs-oxide test strip for one-step solid-phase extraction. After spraying the surface of the SWCNTs-oxide test strip with gold colloids, surface-enhanced Raman scattering signals were greatly increased owing to the clean detection background of the matrix and the concentrated target molecules in the probed volume. A facile approach was recommended here to rapidly monitor simetryn residues in lake water samples using one-step solid-phase extraction with the SWCNTs-oxide test strip and subsequent direct detection on a portable Inspector Raman. The detection limit of this method was found to be 2 μg L−1, and the recovery was between 70 and 80%. In addition, the linearity was in the range 10 to 300 μg L−1 with a correlation coefficient of 0.9878. The method provides a promising approach for the fast analysis of triazine compounds in complex matrix samples.
Co-reporter:Xia-Hong ZHANG, Ting-Yao ZHOU, Xi CHEN
Chinese Journal of Analytical Chemistry 2015 Volume 43(Issue 9) pp:1296-1305
Publication Date(Web):September 2015
DOI:10.1016/S1872-2040(15)60856-8
Novel optical materials are crucial for environmental monitoring. Metal nanoclusters (metal NCs), typically consisting of several to tens of metal atoms, have attracted more and more attention in recent years. Due to their ultra-small size, strong fluorescence, low toxicity, excellent stability and unique core-shell structure, metal NCs have been considered as the promising optical materials for construction of excellent fluorescent sensors. In this review, we mainly focus on the recent application progress of NCs in environmental monitoring, including the detection of pH, heavy metal ions, inorganic anions and nitroaromatic explosives.Metal NCs, including AuNCs, AgNCs, CuNCs and alloy NCs, display excellent fluorescence characteristics and can be used for fluorescence sensing in environmental, such as pH sensing, detection of heavy metal ions, inorganic anions and nitroaromatic explosives.
Co-reporter:Chunshui Lin, Yiying Chen, Zhixiong Cai, Zhi Zhu, Yaqi Jiang, Chaoyong James Yang, Xi Chen
Biosensors and Bioelectronics 2015 Volume 63() pp:562-565
Publication Date(Web):15 January 2015
DOI:10.1016/j.bios.2014.08.011
•This method is label-free with a signal-on sensing mode.•A double-stranded DNA probe was designed as the substrate for ATP-induced super-sandwich.•It is easy, fast and sensitive with a detection limit of 200 pM.•It could perfectly discriminate ATP from its analogs.In this study, a label-free fluorescence strategy for sensitive detection of ATP based on the ligation-triggered super-sandwich is reported. We designed a double-stranded DNA (ds-DNA) probe as the substrate of ATP-dependent ligation. SYBR Green I (SG I), a double-duplex DNA specific dye, was employed as the readout signal. In the absence of ATP, the ligation would not occur and the ds-DNA remained intact. Further, a weak fluorescence could be observed due to the intercalation of SG I into the grooves of the ds-DNA probe. In the presence of ATP, T4 DNA ligase would catalyse the ligation between 3ʹ-OH and 5ʹ-PO4 ends between ds-DNA probes. As a result, more binding sites of the SG I were generated and a fluorescence enhancement was obtained. This method showed a good sensitivity with a detection limit of 200 pM and could perfectly discriminate ATP from its analogs.
Co-reporter:Xiahong Zhang, Genghuang Wu, Zhixiong Cai, Xi Chen
Talanta 2015 Volume 134() pp:132-135
Publication Date(Web):1 March 2015
DOI:10.1016/j.talanta.2014.11.002
•Pt-on-Pd supported on reduced graphene oxide (Pt-on-Pd/RGO) hybrids was synthesized.•Pt-on-Pd/RGO had superior catalytic activity in H2O2 reduction and TMB oxidation.•A sensing approach for H2O2 was developed with a linear range from 0.98 to 130.7 μM.•Methanol electro-catalytic activity of Pt-on-Pd/RGO was higher than that of Pt black.•The dual-functional Pt-on-Pd/RGO was first reported.In this study, a facile hydrothermal method was developed to synthesize Pt-on-Pd supported on reduced graphene oxide (Pt-on-Pd/RGO) hybrids. Because of the synergistic effect between Pt-on-Pd and RGO, the obtained Pt-on-Pd/RGO had superior peroxidase-mimic activities in H2O2 reduction and TMB oxidation. The reaction medium was optimized and a sensing approach for H2O2 was developed with a linear range from 0.98 to 130.7 μM of H2O2. In addition, the characteristic of electrocatalytic oxidation of methanol was investigated. The peak current density value, jf, for the Pt-on-Pd/RGO hybrid (328 mA mg−1Pt) was about 1.85 fold higher than that of commercial Pt black (177 mA mg−1Pt) and, also, more durable electrocatalytic activity could be obtained. For the first time, the dual-functional Pt-on-Pd/RGO with peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic was reported.
Co-reporter:Zhi-xiong Cai;Xin-hong Song;Yi-ru Wang; Xi Chen
ChemElectroChem 2015 Volume 2( Issue 11) pp:1665-1671
Publication Date(Web):
DOI:10.1002/celc.201500239
Abstract
A highly active hydrogen evolution reaction (HER) catalyst was synthesized by loading nickel phosphide (Ni2P) nanosheets self-supported on three-dimensional (3D) graphene/nickel foam (G/NF) by using electrodeposition. The G/NF was firstly prepared through the fast electrodeposition of graphene on NF. Ni2P nanosheets were then fabricated by low-temperature phosphidation of the corresponding precursor of Ni(OH)2 on the G/NF, which was also synthesized through an efficient electrodeposition process. Compared with Ni2P nanosheets on NF without graphene (Ni2P/NF), NF, as well as commercial Pt/C, the Ni2P–G/NF catalyst exhibits high activity in the electrocatalytic HER, revealing a low onset overpotential of 50 mV and a small Tafel slope of 51 mV dec−1. The catalyst maintained its catalytic activity for at least 60 000 s in acidic media. The excellent HER performance of Ni2P–G/NF was attributed to the excellent performance of Ni2P, the large 3D framework, and the introduction of graphene.
Co-reporter:Mingcong Rong, Liping Lin, Xinhong Song, Yiru Wang, Yunxin Zhong, Jiawei Yan, Yufeng Feng, Xiuya Zeng, Xi Chen
Biosensors and Bioelectronics 2015 Volume 68() pp:210-217
Publication Date(Web):15 June 2015
DOI:10.1016/j.bios.2014.12.024
•A label-free and selective determination of chromium (VI) using graphitic carbon nitride nanosheets was proposed.•The determination of ascorbic acid (AA) was developed via an “on–off–on” fluorescence response.•This strategy is effective, facile, cost-effective and fast in response.Using graphitic carbon nitride (g-C3N4) nanosheets, an effective and facile fluorescence sensing approach for the label-free and selective determination of chromium (VI) (Cr(VI)) was developed. The fluorescence of the solution of g-C3N4 nanosheets was quenched effectively by Cr(VI) via the inner filter effect. Under optimal conditions, a wide detection linear range for Cr(VI) was found to be from 0.6 μM to 300 μM with a limit of detection (LOD) of 0.15 μM. In addition, the fluorescence of the solution of g-C3N4 nanosheets-Cr(VI) could be sensitively turned on in the presence of a reductant such as ascorbic acid (AA) via an “on–off–on” fluorescence response through the oxidation–reduction between Cr(VI) and AA. And a wide detection linear range for AA was found to be from 0.5 μM to 200 μM with an LOD of 0.13 μM. Furthermore, the proposed method has the potential application for detection of Cr(VI) in lake waters and AA in biological fluids.
Co-reporter:Tingyao Zhou, Qiuhong Yao, Tingting Zhao, Xi Chen
Talanta 2015 Volume 141() pp:80-85
Publication Date(Web):15 August 2015
DOI:10.1016/j.talanta.2015.03.056
•A facile one-pot approach was developed to prepare fluorescent Cu NCs.•The Cu NCs exhibited excellent water solubility, tiny size and good dispersion.•PVP could enhance the fluorescence intensity of the Cu NCs.•The Cu NCs showed high selectivity and sensitivity for the determination of H2O2.A facile one-pot approach has been developed to prepare orange-emitting Cu nanoclusters (NCs) using tetrakis(hydroxymethyl)phosphonium chloride as a reducing agent and lipoic acid as a capping agent under an alkaline medium at room temperature. The as-prepared Cu NCs exhibited excellent water solubility, large Stokes shift, long lifetime and good dispersion. After the addition of polyvinyl pyrrolidone, the fluorescence intensity of dihydrolipoic acid-stabilized Cu NCs (DHLA-Cu NCs) was greatly enhanced, and their fluorescence signal remained stable for 5 weeks storage in the dark at room temperature. Based on H2O2-induced fluorescence quenching, DHLA-Cu NCs showed high sensitivity and selectivity for the detection of H2O2 in aqueous solution with a detection limit of 0.3 μM, and were applied successfully to the detection of H2O2 in human urine samples.
Co-reporter:Xiaomei Chen, Zhixiong Cai, Xi Chen, Munetaka Oyama
Carbon 2014 Volume 66() pp:387-394
Publication Date(Web):January 2014
DOI:10.1016/j.carbon.2013.09.014
Bimetallic PtPd nanocubes supported on graphene nanosheets (PtPdNCs/GNs) were prepared by a rapid, one-pot and surfactant-free method, in which N,N-dimethylformamide (DMF) was used as a bi-functional solvent for the reduction of both metal precursors and graphene oxide (GO) and for the surface confining growth of PtPdNCs. The morphology, structure and composition of the thus-prepared PtPdNCs/GNs were characterized by transmission electron microscopy (TEM), high resolution TEM, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Because no surfactant or halide ions were involved in the proposed synthesis, the prepared PtPdNCs/GNs were directly modified onto a glassy carbon electrode and showed high electrocatalytic activity for methanol oxidation in cyclic voltammetry without any pretreatments. Moreover, with the synergetic effects of Pt and Pd and the enhanced electron transfer by graphene, the PtPdNCs/GNs composites exhibited higher electrocatalytic activity (jp = 0.48 A mg−1) and better tolerance to carbon monoxide poisoning (If/Ib = 1.27) compared with PtPd nanoparticles supported on carbon black (PtPdNPs/C) (jp = 0.28 A mg−1; If/Ib = 1.01) and PtNPs/GNs (jp = 0.33 A mg−1; If/Ib = 0.95). This approach demonstrates that the use of DMF as a solvent with heating is really useful for reducing GO and metal precursors concurrently for preparing clean metal–graphene composites.
Co-reporter:Chunshui Lin, Zhixiong Cai, Yiru Wang, Zhi Zhu, Chaoyong James Yang, and Xi Chen
Analytical Chemistry 2014 Volume 86(Issue 14) pp:6758
Publication Date(Web):July 1, 2014
DOI:10.1021/ac501730u
A simple, rapid, label-free, and ultrasensitive fluorescence strategy for adenosine triphosphate (ATP) detection was developed using a loop DNA probe with low background noise. In this strategy, a loop DNA probe, which is the substrate for both ligation and digestion enzyme reaction, was designed. SYBR green I (SG I), a double-stranded specific dye, was applied for the readout fluorescence signal. Exonuclease I (Exo I) and exonuclease III (Exo III), sequence-independent nucleases, were selected to digest the loop DNA probe in order to minimize the background fluorescence signal. As a result, in the absence of ATP, the loop DNA was completely digested by Exo I and Exo III, leading to low background fluorescence owing to the weak electrostatic interaction between SG I and mononucleotides. On the other hand, ATP induced the ligation of the nicking site, and the sealed loop DNA resisted the digestion of Exo I and ExoIII, resulting in a remarkable increase of fluorescence response. Upon background noise reduction, the sensitivity of the ATP determination was improved significantly, and the detection limitation was found to be 1.2 pM, which is much lower than that in almost all the previously reported methods. This strategy has promise for wide application in the determination of ATP.
Co-reporter:Zhi-xiong Cai, Cong-cong Liu, Geng-huang Wu, Xiao-mei Chen, Xi Chen
Electrochimica Acta 2014 Volume 127() pp:377-383
Publication Date(Web):1 May 2014
DOI:10.1016/j.electacta.2014.02.055
•Porous 3D dendrite-like structure of Pt-on-Pd bimetallic nanostructures supported on graphene were prepared.•The surface of nanostructures was very “clean” because of the surfactant-free formation process and the use of green reagent.•The hetero-nanostructures showed excellent electrocatalytic performance in methanol oxidation.A green synthesis of Pt-on-Pd bimetallic nanodendrites supported on graphene (GPtPdNDs) with a Pd interior and a dendrite-like Pt exterior was achieved using a two-step preparation, mixing graphene and PdCl42− first, then adding PtCl42− and ethanol without any other solvent. The morphology, structure and composition of the thus-prepared GPtPdNDs were characterized by transmission electron microscopy (TEM), high resolution TEM, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Because no halide ions (refer in particular to Br-, I−) or surfactant was involved in the synthesis, the prepared GPtPdNDs were directly modified onto a glassy carbon electrode and showed excellent electrocatalytic performance in methanol oxidation without any pretreatments. Moreover, with the special structure of PtPdNDs and the synergetic effects of Pt and Pd and the enhanced electron transfer by graphene, the GPtPdNDs composites exhibited higher electrocatalytic activity and better tolerance to Pt nanoparticles supported on graphene (GPtNPs) and Pt/C for methanol oxidation.
Co-reporter:Na Xu, Yiru Wang, Mingcong Rong, Zhifeng Ye, Zhuo Deng, Xi Chen
Journal of Chromatography A 2014 Volume 1364() pp:53-58
Publication Date(Web):17 October 2014
DOI:10.1016/j.chroma.2014.08.081
•g-C3N4 can be used as a coating material for SPME applications.•g-C3N4 fiber can be applied to extract both low- and high- polarity analytes.•g-C3N4 fiber reveals excellent extraction ability and durability.In this study, graphitic carbon nitride (g-C3N4) was used as a coating material for solid-phase microextraction (SPME) applications. Coupled to gas chromatography (GC), the extraction ability of the SPME fiber was investigated and compared with the commercial fibers of 100 μm PDMS and 85 μm CAR/PDMS using six target analytes including deltamethrin, nerolidol, amphetamine, dodecane, ametryn and acrylamide. The g-C3N4 coating revealed excellent extraction ability and durability comparing with those of the commercial fibers due to its loose structure and unique physicochemical properties. The repeatability for each single fiber was found to be 3.46% and reproducibility for fiber to fiber was 8.53%. The g-C3N4 SPME fiber was applied to the determination of acrylamide in potato chips, the linearity and detection limit was 0.5-250 μg g−1 and 0.018 μg g−1, respectively.
Co-reporter:Chunhua Ma, Yanqin Qu, Yingxue Zhang, Bin Qiu, Yiru Wang, Xi Chen
Food Chemistry 2014 Volume 152() pp:285-290
Publication Date(Web):1 June 2014
DOI:10.1016/j.foodchem.2013.11.010
•A novel approach using HS-SPME–GC is studied and applied for the quantitative determination of nerolidol in teas.•The generation and variation of the nerolidol contents in teas during the tea manufacturing process are studied.•The correlation between nerolidol and Oolong tea quality had been analyzed.Nerolidol is an important volatile compound found in tea aroma, consumption of which has been associated with good health. A novel approach for the quantitative determination of nerolidol in teas has been developed using a headspace solid phase microextraction (HS-SPME) and a gas chromatography-flame ionization detector (GC-FID). The experimental parameters relating to the extraction efficiency of the HS-SPME such as fibre types, extraction temperature, extraction time, stirring rate were investigated and optimized. The study results demonstrated that combining GC-FID with HS-SPME was an efficient and flexible extraction approach for the analysis of nerolidol in teas. Using the HS-SPME–GC-FID, the linear range of the determination of nerolidol was found to be 2.7–1360 ng g−1 and the limit of detection was 0.3 ng g−1. The average recoveries were in the range 78.7–106% in spiked tea samples. In addition, the generation and the content change in nerolidol at different manufacturing stages were investigated. Based on the content of nerolidol in Oolong tea samples, grade judgment for the various teas was performed.
Co-reporter:Chunshui Lin, Yanfang Wu, Feng Luo, Dongmei Chen, Xi Chen
Biosensors and Bioelectronics 2014 Volume 59() pp:365-369
Publication Date(Web):15 September 2014
DOI:10.1016/j.bios.2014.03.053
•We take advantage of the specific affinity between methylene blue and unbound guanine bases.•We designed a double-stranded probe with many unbound guanines for specific DNA detection.•The target DNA can induce a simple exonuclease III assisted cleavage process.•This method is label-free and sensitive.In this work, using methylene blue (MB) as a redox marker and exonuclease III (Exo III) as an amplificatory enzyme, we developed a facile and a label-free electrochemical method for sensitive DNA detection. A double-stranded DNA (dsDNA) probe was prepared by hybridizing two single-stranded DNA (ssDNA) probes. In the ssDNA probes, one ssDNA was guanine bases free and the other one consisted of many unbound guanine bases. MB could be absorbed on the unbound guanine bases owing to the specific interaction between MB and the guanine bases. When the dsDNA probe was challenged with target DNA, it induced a simple Exo III assisted cleavage process, accompanied by the release of the unbound guanine bases. Thus, the amount of MB absorbed on the electrode was much less compared to the initial signal. The detection limit for DNA was found to be as low as 20 fM. Moreover, it could discriminate mismatched DNA from perfectly matched target DNA. This detection method is simple in design, fast in operation and can be applied to detect different DNA sequences.
Co-reporter:Yan-fang Wu, Zhi-min Cai, Geng-huang Wu, Ming-cong Rong, Ya-qi Jiang, Chao-yong James Yang, Xi Chen
Sensors and Actuators B: Chemical 2014 191() pp: 60-66
Publication Date(Web):
DOI:10.1016/j.snb.2013.09.050
Co-reporter:Xiahong Zhang, Sisi Lu, Xi Chen
Sensors and Actuators B: Chemical 2014 198() pp: 268-273
Publication Date(Web):
DOI:10.1016/j.snb.2014.02.094
Co-reporter:Liping Lin, Mingcong Rong, Feng Luo, Dongmei Chen, Yiru Wang, Xi Chen
TrAC Trends in Analytical Chemistry 2014 Volume 54() pp:83-102
Publication Date(Web):February 2014
DOI:10.1016/j.trac.2013.11.001
•Methods for preparing luminescent graphene quantum dots (GQDs).•Methods for tuning the surface chemistry of luminescent graphene quantum dots (GQDs).•Physical and chemical properties of luminescent graphene quantum dots (GQDs).•Applications of luminescent graphene quantum dots (GQDs) in different fields.•Some issues for further studies of luminescent graphene quantum dots (GQDs).Luminescent graphene quantum dots (GQDs) have attracted tremendous attention from the scientists in chemistry, materials science, physics and biology, because of their superiority of good stability, excellent optical and electrochemical properties, resistance to photobleaching and low cytotoxicity. We summarize the recent advances in the preparation and the properties of GQDs and their applications in environmental and biological areas. In addition, we discuss the future development of GQDs.
Co-reporter:Xinhong Song, Liping Lin, Mingcong Rong, Yiru Wang, Zhaoxiong Xie, Xi Chen
Carbon 2014 80() pp: 174-182
Publication Date(Web):
DOI:10.1016/j.carbon.2014.08.054
Co-reporter:Congcong Liu, Feng Luo, Dongmei Chen, Bin Qiu, Xinhua Tang, Huixian Ke, Xi Chen
Talanta 2014 Volume 123() pp:95-100
Publication Date(Web):June 2014
DOI:10.1016/j.talanta.2014.01.019
•A fluorescence method was developed for AA determination in food samples.•AA was degraded through Hofmann reaction to generate vinyl amine.•The fluorescence responded to the reaction between fluorescamine and vinyl amine.•Fluorescence intensity was linear to the square-root of AA concentration.•This method showed high sensitivity in the determination of AA in food samples.A simple and rapid fluorescence method has been developed for the determination of acrylamide in heat-processed food samples. In the determination, acrylamide is degraded through Hofmann reaction to generate vinyl amine, and pyrrolinone is produced when the vinyl amine reacts with fluorescamine, resulting in a strong fluorescence emission at 480 nm. Hofmann reaction is a key step for the fluorescence determination of acrylaminde, and the reaction conditions are investigated and optimized. Under the optimal conditions, the fluorescence intensity increases with the increase of acrylamide concentrations. The linear range between the fluorescence intensity and the square-root of acrylamide concentrations is from 0.05 μg mL−1 to 20 μg mL−1 with the correlation coefficient R2=0.9935. The detection limit is 0.015 μg mL−1 and the recovery for food samples is from 66.0% to 110.6%. In comparison with Specification of Entry&Exit Inspection and Quarantine Bureau of The People׳s Republic of China (SN/T 2281-2009), the method showed comparable results and demonstrated the accuracy of the method.Based on the Hofmann reaction, acrylamide was degraded to generate vinyl amine, and pyrrolinone was produced when the vinyl amine reacted with fluorescamine, resulting in a strong fluorescence emission at 480 nm. The proposed method was successfully applied in acrylamide determination in complex heat-processed food matrices.
Co-reporter:Zhimin Cai, Yiying Chen, Chunshui Lin, Yanfang Wu, Chaoyong James Yang, Yiru Wang, Xi Chen
Biosensors and Bioelectronics 2014 Volume 61() pp:370-373
Publication Date(Web):15 November 2014
DOI:10.1016/j.bios.2014.05.046
•A dual-signal amplification method based on two molecular beacons was designed.•An ssDNA with 10 T bases at 3′-termini could resist the Exo III digestion.•This method can discriminate single base mismatched targets well.A dual-signal amplification method based on two molecular beacons was designed for human hemochromatosis (HFE) gene detection. The two probes, P1 and P2, could resist the exonuclease III (Exo III) digestion due to the 3′-termini protrusion, and could coexist stably with Exo III. In the presence of HFE targets, P1 hybridized with a HFE target to form a duplex DNA with a recessed 3′-hydroxyl termini and then partially digested by Exo III, releasing the HFE target and a residual sequence (X). This X sequence could trigger the digestion of P2 probes with 6-carboxy-fluoresceins and Black Hole Quenchers and then result in the increase of fluorescence intensity. The X sequences were more stable than HFE targets and could cyclically trigger the P2 digestion for a long time even though the HFE targets were digested by Exo III. This method improved the sensitivity and reached 4 orders of magnitude in detection limit, and showed excellent selectivity to discriminate single base mismatched targets well.
Co-reporter:Chunhua Ma, Jiaojiao Ji, Connieal Tan, Dongmei Chen, Feng Luo, Yiru Wang, Xi Chen
Talanta 2014 Volume 120() pp:94-99
Publication Date(Web):March 2014
DOI:10.1016/j.talanta.2013.11.021
•We developed an HS-SPME–GC–FID method for the analysis of aldehydes generated from edible oils, which is straightforward, simple, rapidly specified and accurate.•The study confirmed that the level of aldehydes, especially hexanal, is adequate as a parameter to measure oil deterioration.•The results of our study confirmed that the concentration of hexanal was related with the storage time of the edible oils.Oxidation has important effects on the quality of edible oils. In particular, the generation of aldehydes produced by the oxidation of oils is one of the deteriorative factors to their quality. The aim of this study was to develop a method to determine the aldehydes as lipid oxidation markers in edible oils. Seven aldehydes generated from lipid oxidation were studied using headspace solid-phase microextraction coupled to gas chromatography with a flame ionization detector. The extraction efficiency of five commercial fibers was investigated and the influence of extraction temperature, extraction time, desorption temperature, and desorption time were optimized. The best result was obtained with 85 μm carboxen/polydimethylsiloxane, extraction at 50 °C for 15 min and desorption in the gas chromatography injector at 250 °C for 2 min. Under the optimized conditions, the content of hexanal was the highest of the seven aldehydes in all edible oils. The limits of detection for hexanal in the three oils were found to range from 4.6 to 10.2 ng L−1. The reproducibility of the method was evaluated and the relative standard deviations were less than 8.9%. This developed approach was successfully applied to analyze hexanal in peanut oil, soy oil, and olive oil samples, and these results were compared with those obtained using the thiobarbituric acid-reactive substances (TBARs) method.
Co-reporter:Huaizhi Kang, Liping Lin, Mingcong Rong, Xi Chen
Talanta 2014 Volume 129() pp:296-302
Publication Date(Web):1 November 2014
DOI:10.1016/j.talanta.2014.05.054
•A cross-reactive sensor array has been designed for the heavy metal ions detection.•The fluorescent nanoclusters were used as partial indicators for the heavy metal ions detection.•The sensor array showed good discriminatory capacity to heavy metal ions in different pHs.•The results of the sensor array applied in known and unknown samples showed its practicality.A cross-reactive sensor array using mercaptopropionic acid modified cadmium telluride (CdTe), glutathione modified CdTe, poly(methacrylic acid) modified silver nanoclusters, bovine serum albumin modified gold nanoclusters, rhodamine derivative and calcein blue as fluorescent indicators has been designed for the detection of seven heavy metal ions (Ag+, Hg2+, Pb2+, Cu2+, Cr3+, Mn2+ and Cd2+). The discriminatory capacity of the sensor array to different heavy metal ions in different pH solutions has been tested and the results have been analyzed with linear discriminant analysis. Results showed that the sensor array could be used to qualitatively analyze the selected heavy metal ions. The array performance was also evaluated in the identification of known and unknown samples and the preliminary results suggested the promising practicability of the designed sensor assay.A cross-reactive sensor array using mercaptopropionic acid modified cadmium telluride (CdTe), glutathione modified CdTe, poly(methacrylic acid) modified silver nanoclusters, bovine serum albumin modified gold nanoclusters, rhodamine derivative and calcein blue as fluorescent probes has been designed for the detection of seven heavy metal ions (Ag+, Hg2+, Pb2+, Cu2+, Cr3+, Mn2+ and Cd2+). The discriminatory capacity of the sensor array to different heavy metal ions in different pH solutions has been tested and the results have been analyzed with linear discriminant analysis. And the array performance was also evaluated in the identification of known and unknown samples.Color changes of fluorescent probes in the absence and presence of heavy metal ions under 365 nm UV light in the HEPES buffer solution of pH 7.0.
Co-reporter:Connieal Tan;Yiru Wang;Zhuo Deng;Na Xu;Xinhong Song;Haihong Liu
Microchimica Acta 2014 Volume 181( Issue 7-8) pp:821-828
Publication Date(Web):2014 June
DOI:10.1007/s00604-013-1137-x
We report on a preconcentration disk for the determination of trace amounts of heterocyclic aromatic amines (HAAs) in the groups of quinoline and quinoxaline congeners as possible human carcinogens. The disk is based on nanocomposite (NC) prepared from graphene oxide as the precursor and from gold nanoparticles that act as building blocks to form a three-dimensional NC. If deposited in the sampling valve of a HPLC system, the material displays excellent extraction capability for HAAs owing to its large surface and π-π stacking interaction. Following an optimization of the extraction parameters, the method was successfully applied to the simultaneous determination of polar HAAs in meat samples with detection limit of 0.09 to 0.16 ng g−1 and recoveries of 69.5 to 122.7 %. The disk was used in more than 150 subsequent preconcentration cycles without obvious loss of the absorption capability. The results reveal that this new NC represents an excellent sorbent for purposes of preconcentration.
Co-reporter:Xiaomei Chen;Genghuang Wu;Zhixiong Cai;Munetaka Oyama
Microchimica Acta 2014 Volume 181( Issue 7-8) pp:689-705
Publication Date(Web):2014 June
DOI:10.1007/s00604-013-1098-0
Enzyme-free (also called non-enzymatic or direct) electrochemical sensors have been widely used for the determination of hydrogen peroxide, glucose, and uric acid. This review covers the recent progress made in this field. We also discuss the respective sensor materials which have strong effect on the electro-catalytic properties of the electrodes and govern the performance of these sensors. In addition, perspectives and current challenges of enzyme-free electrochemical sensors are outlined. Contains 142 references.
Co-reporter:Xiaomei Chen, Zhixiong Cai, Zhiyong Huang, Munetaka Oyama, Yaqi Jiang and Xi Chen
Nanoscale 2013 vol. 5(Issue 13) pp:5779-5783
Publication Date(Web):25 Mar 2013
DOI:10.1039/C3NR00848G
An enzyme-free oxalic acid (OA) electrochemical sensor was assembled using a platinum nanoparticle-loaded graphene nanosheets (PtNPGNs)-modified electrode. The PtNPGNs, with a high yield of PtNPs dispersed on the graphene nanosheets, were successfully achieved by a green, rapid, one-step and template-free method. The resulting PtNPGNs were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and an X-ray diffraction technique. Electrochemical oxidation of OA on the PtNPGNs-modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry methods. Based on the results, the modified electrode exhibited high electrochemical activity with well-defined peaks of OA oxidation and a notably decreased overpotential compared to the bare or even the GNs-modified electrode. Under optimized conditions, a good linear response was observed for the concentration of OA and its current response was in the range of 0.1–15 mM and 15–50 mM with a detection limit (S/N = 3) of 10 μM. Furthermore, the electrochemical sensor presented good characteristics in terms of stability and reproducibility, promising the applicability of the sensor in practical analysis.
Co-reporter:Ting-yao Zhou, Li-ping Lin, Ming-cong Rong, Ya-qi Jiang, and Xi Chen
Analytical Chemistry 2013 Volume 85(Issue 20) pp:9839
Publication Date(Web):September 9, 2013
DOI:10.1021/ac4023764
In this paper, the development of a simple method is described for preparing highly red fluorescent mercaptosuccinic acid stabilized AgAu alloy nanoclusters (MSA–AgAu NCs) through the core etching of Ag nanoparticles (NPs) and a galvanic exchange reaction using nonorganic solvent and no multistep centrifuge washing. The as-prepared MSA–AgAu NCs were characterized using spectroscopic and microscopic techniques. After covalently attaching methoxy-poly(ethylene glycol)-NH2 (m-PEG-NH2), PEGylated MSA–AgAu NCs were still stable even in 1 M NaCl. Probably based on the deposition of Al3+-enhanced fluorescence, the PEGylated MSA–AgAu NCs offered highly selective and sensitive sensing of Al3+ in aqueous solution with a detection limit of 0.8 μM.
Co-reporter:Zhi-xiong Cai, Cong-cong Liu, Geng-huang Wu, Xiao-mei Chen, Xi Chen
Electrochimica Acta 2013 Volume 112() pp:756-762
Publication Date(Web):1 December 2013
DOI:10.1016/j.electacta.2013.09.040
A facile spontaneous redox method is developed to obtain uniform palladium nanoparticles (PdNPs) distributed on surfactant-functionalized multi-walled carbon nanotubes (MWCNTs) at room temperature. In this synthesis, hexadecyltrimethylammonium bromide (CTAB) was self-assembled onto MWCNTs to provide adsorption sites for PdCl42− ions. Interestingly, PdCl42− was spontaneously reduced though a galvanic cell effect between PdCl42− and MWCNTs. The as-prepared Pd catalyst showed excellent catalytic activity toward oxidation of ethanol and glucose in an alkaline medium. Inspired by this, a glucose enzyme-free biosensor was developed with a wide linear range covering from 1 mM to 20 mM and a high sensitivity of 11 μA mM−1 cm−2 (to 1–10 mM) and 6.3 μA mM−1 cm−2 (to 11–20 mM). These results indicate that the as-synthesized Pd catalyst could be a great potential material for improving performance of direct ethanol fuel cells and glucose sensors.
Co-reporter:Xiao-mei Chen, Zhi-xiong Cai, Zhi-yong Huang, Munetaka Oyama, Ya-qi Jiang, Xi Chen
Electrochimica Acta 2013 Volume 97() pp:398-403
Publication Date(Web):1 May 2013
DOI:10.1016/j.electacta.2013.02.047
A nonenzymatic electrochemical method was developed for hydrogen peroxide (H2O2) detection using an electrode modified with palladium nanoparticles (PdNPs)-graphene nanosheets (PdNPGNs). Ultrafine PdNPs were homogeneously modified on graphene nanosheets through a facile spontaneous redox reaction and characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy technique. Based on the voltammetric and amperometric results, the PdNPGNs-modified glassy carbon electrode (PdNPGNs-GCE) demonstrated direct and mediatorless responses to H2O2 at a low potential. The analytical performances of the PdNPGNs-GCE toward H2O2 reduction was evaluated in the linear response range from 0.1 μM to 1.0 mM, with a detection limit (S/N = 3) of 0.05 μM. The PdNPGNs-GCE showed excellent resistance toward poisoning from such interfering species as ascorbic acid, dopamine and glucose. Furthermore, the electrochemical sensor presented good characteristics in terms of stability and reproducibility, promising the applicability of this sensor in practical analysis.
Co-reporter:Yanfang Wu, Jinhua Huang, Tingyao Zhou, Mingcong Rong, Yaqi Jiang and Xi Chen
Analyst 2013 vol. 138(Issue 19) pp:5563-5565
Publication Date(Web):24 Jul 2013
DOI:10.1039/C3AN01207G
A gold nanocluster@bovine serum albumin–silica nanoparticle composite has been synthesized and used for the solid-state electrochemiluminescence (ECL) sensing of hydrogen peroxide. The ECL characteristics have also been studied.
Co-reporter:Leihong Gao;Jing Zou;Haihong Liu;Jingbin Zeng;Yiru Wang
Journal of Separation Science 2013 Volume 36( Issue 7) pp:1298-1303
Publication Date(Web):
DOI:10.1002/jssc.201201060
A method for the quantitative determination of bisphenol A in thermal printing paper was developed and validated. Bisphenol A was extracted from the paper samples using 2% NaOH solution, then the extracted analyte was enriched using single-drop microextraction followed by HPLC analysis. Several parameters relating to the single-drop microextraction efficiency including extraction solvent, extraction temperature and time, stirring rate, and pH of donor phase were studied and optimized. Spiked recovery of bisphenol A at 20 and 5 mg/g was found to be 95.8 and 108%, and the method detection limit and method quantification limit was 0.03 and 0.01 mg/g, respectively. Under the optimized conditions, the proposed method was applied to the determination of bisphenol A in seven types of thermal printing paper samples, and the concentration of bisphenol A was found in the range of 0.53–20.9 mg/g. The considerably minimum usage of organic solvents (5 μL 1-octanol) and high enrichment factor (189–197) in the sample preparation are the two highlighted advantages in comparison with previously published works.
Co-reporter:Yanqin Qu;Congcong Liu;Feng Luo;Bin Qiu
Journal of Separation Science 2013 Volume 36( Issue 24) pp:3889-3895
Publication Date(Web):
DOI:10.1002/jssc.201300694
We developed a solid-phase microextraction coupled to GC with electron-capture detection method for the detection of acrylamide in food samples. Single-walled carbon nanotubes and polypyrrole were electropolymerized onto a stainless-steel wire as a coating, which possessed a homogeneous, porous, and wrinkled surface, chemical and mechanical stability, long lifespan (over 300 extractions), and good extraction efficiency for acrylamide. The linearity range between the signal intensity and the acrylamide concentration was found to be in the range 0.001–1 μg/mL, and the coefficient of determination was 0.9985. The LOD, defined as three times the baseline noise, was 0.26 ng/mL. The reproducibility for each single fiber (n = 6) and the fiber-to-fiber (n = 5) repeatability prepared in the same batch were less than 4.1 and 11.2%, respectively.
Co-reporter:Chunhua Ma, Liping Lin, Yanyan Du, Liang-bi Chen, Feng Luo and Xi Chen
Analytical Methods 2013 vol. 5(Issue 7) pp:1843-1847
Publication Date(Web):04 Feb 2013
DOI:10.1039/C3AY26492K
A fluorescent probe, a rhodamine 6G derivative (R6GD), has been designed and synthesized for the determination of Fe(III). In HAc–NaAc buffer solution, R6GD exhibits highly selective and sensitive response toward Fe(III) based on the fluorescence quenching mechanism of R6GD due to the heavy atom effect of I3− formed in the reaction between KI and Fe(III). Under the optimal conditions, the concentration of Fe(III) showed good linear relationship with the fluorescence intensity change of R6GD. The linear response range of Fe(III) (R2 = 0.9923) was found from 0.1 to 6.0 μmol L−1 with the detection limit of 0.05 μmol L−1 of Fe(III). The recovery of the approach in the determination of Fe(III) in real water samples was 83.3–99.5%.
Co-reporter:Geng-huang Wu, Xin-hong Song, Yan-Fang Wu, Xiao-mei Chen, Feng Luo, Xi Chen
Talanta 2013 Volume 105() pp:379-385
Publication Date(Web):15 February 2013
DOI:10.1016/j.talanta.2012.10.066
A non-enzymatic electrochemical method was developed for glucose detection using a glassy carbon electrode modified with platinum nanoflowers supported on graphene oxide (PtNFs-GO). PtNFs-GO was synthesized using a nontoxic, rapid, one-pot and template-free method. Low-cost, green solvent ethanol acted as the reductant, and the advanced and effective 2D carbon material-GO nanosheet acted as the stabilizing material. Their morphologies were characterized using transmission electron microscopy. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards glucose in neutral media. The modified electrode exhibited strong and sensitive amperometric responses to glucose even in the presence of a high concentration of chloride ions. The response time was within 5 s. The interference effects from ascorbic acid and uric acid were comparatively small when operated at suitable potential. Under optimal detection potential (0.47 V with a saturated calomel reference electrode) the PtNFs-GO modified electrode performed a current response towards glucose at a broad concentration range from 2 μM to 20.3 mM. Two linear regions could be observed at 2 μM to 10.3 mM with a sensitivity of 1.26 μA mM−1 cm−2 (correlation coefficient 0.9968), and at 10.3 mM to 20.3 mM with a sensitivity of 0.64 μA mM−1 cm−2(correlation coefficient 0.9969). The LOD of 2 μM was lower than many non-enzymatic electrochemical glucose sensors. The modified electrode was also applied to the determination of glucose in glucose injection solutions, and the satisfactory results obtained indicated that it was promising for the development of a novel non-enzymatic electrochemical glucose sensor.Highlights► PtNFs-GO was synthesized using a nontoxic, one-pot and template-free method. ► PtNFs-GO modified electrode exhibited a rapid response to glucose (within 5 s). ► Modified electrode retains sensitivity in the presence of chloride ions. ► Broad linear concentration range from 2 μM to 20.3 mM and low LOD of 2 μM.
Co-reporter:Yanyan Du, Min Chen, Yingxue Zhang, Feng Luo, Chunyan He, Meijin Li, Xi Chen
Talanta 2013 Volume 106() pp:261-265
Publication Date(Web):15 March 2013
DOI:10.1016/j.talanta.2012.10.078
A new method for determination of iron(III) has been developed using a kind of rhodamine B derivative fluorescent probe, rhodamine amide (RHA), in acidic HAc–NaAc buffer solution. In this approach, the heavy atom effect of I3− was applied to quench the fluorescence of RHA. When iron(III) and KI coexisted in HAc–NaAc buffer solution, iron(III) reacted with the excess KI to produce I3− that quenched the fluorescence of RHA through the formation of a non-fluorescence compound. The results showed that the fluorescence intensity decrease of RHA presented a good linear relationship with the iron(III) concentrations in the range from 0.5 to 5.0 μmol L−1 with the correlation coefficient of 0.9970, and the detection limit was 0.3 μmol L−1 iron(III). The approach was applied to determination of iron(III) in water samples, and the recovery was found to be from 80.7% to 100. 8%.Highlights► A fluorescence method was developed for determination of iron(III) in water. ► This method relies on the heavy atom effect of I3− to quench the rhodamine B amide. ► This method shows high sensitivity and good selectivity toward iron(III). ► This method has been applied in the determination of iron(III) in water samples.
Co-reporter:Qi Lin;HongMei Lin;YuanHui Zhang;MingCong Rong;HuiXian Ke
Science China Chemistry 2013 Volume 56( Issue 12) pp:1749-1756
Publication Date(Web):2013 December
DOI:10.1007/s11426-013-4922-9
In this work, we reported a simultaneous determination approach for Pb(II), Cd(II) and Zn(II) at μg L−1 concentration levels using differential pulse stripping voltammetry on a bismuth film electrode (BiFE). The BiFE could be prepared in situ when the sample solution contained a suitable amount of Bi(NO)3, and its analytical performance was evaluated for the simultaneous determination of Pb(II), Cd(II) and Zn(II) in solutions. The determination limits were found to be 0.19 μg L−1 for Zn(II), and 0.28 μg L−1 for Pb(II) and Cd(II), with a preconcentration time of 300 s. The BiFE approach was successfully applied to determine Pb(II), Cd(II) and Zn(II) in tea leaf and infusion samples, and the results were in agreement with those obtained using an atomic absorption spectrometry approach. Without Hg usage, the in situ preparation for BiFE supplied a green and acceptability sensitive method for the determination of the heavy metal ions.
Co-reporter:Xiaomei Chen, Bingyuan Su, Genghuang Wu, Chaoyong James Yang, Zhixia Zhuang, Xiaoru Wang and Xi Chen
Journal of Materials Chemistry A 2012 vol. 22(Issue 22) pp:11284-11289
Publication Date(Web):04 Apr 2012
DOI:10.1039/C2JM31133J
This paper reports a nontoxic, rapid, one-pot and template-free synthesis of three-dimensional (3D) Pt nanoflowers (PtNFs) with high yield and good size monodispersity supported on graphene oxide (GO) nanosheets. The key synthesis strategy employed a low-cost, green solvent, ethanol as the reductant and an advanced, powerful 2D carbon material, GO nanosheets as the stabilizing material. The resulting PtNFs-GO nanosheets were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. It was found that the monodispersed, porous PtNFs supported on GO nanosheets were a uniform size of 30 nm and each was composed of numerous “clean” and small (4 nm) Pt nanoparticles, which revealed an unusually high activity for methanol oxidation reaction compared to commercial Pt black. Furthermore, based on a systematic study of the PtNFs growth conditions, a possible mechanism, and especially the importance of GO in the formation was proposed. Our study demonstrates that GO is a promising support material for developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.
Co-reporter:Tingyao Zhou, Yunhe Huang, Wenbin Li, Zhimin Cai, Feng Luo, Chaoyong James Yang and Xi Chen
Nanoscale 2012 vol. 4(Issue 17) pp:5312-5315
Publication Date(Web):10 Jul 2012
DOI:10.1039/C2NR31449E
A facile approach was developed to prepare positively charged and red-emitting lysozyme-stabilized Ag nanoclusters (Lys-AgNCs) using NaBH4 as a reducing agent at room temperature. The Lys-AgNCs can be applied in the highly selective detection of Hg2+.
Co-reporter:Tingyao Zhou, Mingcong Rong, Zhimin Cai, Chaoyong James Yang and Xi Chen
Nanoscale 2012 vol. 4(Issue 14) pp:4103-4106
Publication Date(Web):08 May 2012
DOI:10.1039/C2NR30718A
A facile one-pot sonochemical approach is presented to prepare highly blue-emitting Ag nanoclusters (AgNCs) using glutathione as a stabilizing agent in aqueous solution. The as-prepared AgNCs can be applied in the selective detection of S2− with a limit of detection of 2 nM based on fluorescence quenching.
Co-reporter:Lan Luan, Zhi-jie Lin, Xi-wei Liu, Xu-dong Wang and Xi Chen
Analyst 2012 vol. 137(Issue 10) pp:2459-2461
Publication Date(Web):12 Mar 2012
DOI:10.1039/C2AN00026A
Tris(4,7-diphenyl-1,10-phenanthroline)-ruthenium(II) (Rudpp) doped oxygen-resisting nanobeads were synthesized and applied in order to study the effects of oxygen on electrochemiluminescence.
Co-reporter:Tingxiu Ye, Chunyan He, Yanqin Qu, Zhuo Deng, Yaqi Jiang, Meijin Li and Xi Chen
Analyst 2012 vol. 137(Issue 18) pp:4131-4134
Publication Date(Web):19 Jul 2012
DOI:10.1039/C2AN35422E
A ‘turn-on’ fluorescent colorimetric device for Hg2+ sensing was built using a dual light-emitting diode system. Fluorescence generated from a rhodamine derivative (RHD), an indicator for Hg2+ sensing, was combined with a background red light, and the complex light was captured by a commercial charge coupled device camera or by the naked eye.
Co-reporter:Jiaojiao Ji, Haihong Liu, Jinmei Chen, Jingbin Zeng, Jianli Huang, Leihong Gao, Yiru Wang, Xi Chen
Journal of Chromatography A 2012 Volume 1246() pp:22-27
Publication Date(Web):13 July 2012
DOI:10.1016/j.chroma.2012.01.080
Zinc oxide (ZnO) nanorods based solid-phase microextraction (SPME) coating was directly prepared on stainless steel wires using in situ hydrothermal growth method. This coating has high surface-to-volume ratio with a diameter in the range of 300–500 nm and a thickness of about 3–5 μm. A guiding tube was introduced into the laboratory-made SPME fiber to protect the ZnO nanorods coating from shaving, which significantly improved the method repeatability and prolonged the service life of the coating. The extraction properties of the prepared fiber were investigated using headspace SPME (HS-SPME) coupled to gas chromatography (GC) for the determination of aldehydes in instant noodle samples. The extraction efficiency of the coating for the five aldehydes was comparable to that of a commercial 85 μm Carboxen/Polydimethylsiloxane fiber, which has been reported to have best affinity towards aldehydes among all commercial fibers. The linear ranges of the proposed HS-SPME-GC method were from 0.05 to 5 μg g−1 (hexanal, nonanal and decanal) and 0.1–5 μg g−1 (heptanal and octanal), with the correlation coefficients from 0.990 to 0.999. The method developed was successfully applied to the determination of five aldehydes in instant noodle samples, and the recoveries were found to be 70.5–129% at the spiking level of 2 μg g−1.Highlights► We directly synthesize ZnO nanorods onto a stainless steel wire as an SPME coating. ► A guiding tube is introduced to protect the coating from shaving. ► This coating shows excellent extraction efficiency towards aldehydes. ► The developed method is suitable for the analysis of aldehydes in instant noodles.
Co-reporter:Chun-hua Ma, Ya-mei Shi, Liang-bi Chen, Yan-fang Wu and Xi Chen
Analytical Methods 2012 vol. 4(Issue 12) pp:4096-4100
Publication Date(Web):03 Oct 2012
DOI:10.1039/C2AY25878A
In this paper, an electrochemiluminescence (ECL) sensor is fabricated using a covalent bond immobilization approach. A glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs@GCE) was prepared using a wet chemical method which acts as a support for the ECL reagent. A monolayer of mercaptoacetic acid (MA) was then assembled onto the AuNPs@GCE surface. Finally, an ECL reagent, bis(2,2′-bipyridyl) (5-amno-1,10-phen) dichlororuthenium [Ru(bpy)2(phen-NH2)]22+, was attached onto the AuNPs@GCE by condensation of the amino group and carboxylic group of MA. Because [Ru(bpy)2(phen-NH2)]22+ is covalently immobilized on the electrode surface without any polymaterials and directly contacts to the electrolyte, in contrast to traditional ECL sensors fabricated using a polymer technique, mass transportation and electron transfer hindrance is negligible and ECL stability is increased obviously. The sensor is applied in cathodic ECL analysis and presents good performance in a linear range from 1.0 × 10−6 mol L−1 to 0.1 mol L−1 and a detection limit of 5 × 10−7 mol L−1 for potassium persulfate.
Co-reporter:Ting-xiu Ye, Yan-yan Du, Chun-yan He, Bin Qiu, Yi-ru Wang and Xi Chen
Analytical Methods 2012 vol. 4(Issue 4) pp:1001-1004
Publication Date(Web):21 Mar 2012
DOI:10.1039/C2AY25073J
Core-shell silica particles encapsulating two luminescent dyes with different emission wavelengths were prepared for ratiometric fluorescence sensing of pH. The composite core-shell structure particles contained a polyacrylonitrile (PAN) core surrounding a silica shell. Fluorescein isothiocyanate (FITC) encapsulated in the silica shell was taken as an indicator, Fluorescence emission from Ru(dpp)3(ClO4)2 immobilized in PAN core was used as a reference light. The ratiometric fluorescence signal from the core-shell silica particles were found with a linear range from pH 5.80 to 7.50 (R2 = 0.997). In addition, the morphology of the core-shell silica particles, the effects of temperature and co-existing substances were investigated. The core-shell silica particles were successfully applied to determination of pH value in water and urine samples.
Co-reporter:Geng-huang Wu, Yan-fang Wu, Xi-wei Liu, Ming-cong Rong, Xiao-mei Chen, Xi Chen
Analytica Chimica Acta 2012 745() pp: 33-37
Publication Date(Web):
DOI:10.1016/j.aca.2012.07.034
Co-reporter:Chun-Hua Lu, Yan Zhang, Shui-Fen Tang, Zhi-Bin Fang, Huang-Hao Yang, Xi Chen, Guo-Nan Chen
Biosensors and Bioelectronics 2012 Volume 31(Issue 1) pp:439-444
Publication Date(Web):15 January 2012
DOI:10.1016/j.bios.2011.11.008
We have developed a biomimetic sensor for the detection of human immunodeficiency virus type 1 (HIV-1) related protein (glycoprotein 41, gp41) based on epitope imprinting technique. gp41 is the transmembrane protein of HIV-1 and plays an important role in membrane fusion between viruses and infected cells. It is an important index for determining the extent of HIV-1 disease progression and the efficacy of therapeutic intervention. In this work, dopamine was used as the functional monomer and polymerized on the surface of quartz crystal microbalance (QCM) chip in the presence of template, a synthetic peptide with 35 amino acid residues, analogous to residues 579–613 of the gp41. This process resulted in grafting a hydrophilic molecularly imprinted polymer (MIP) film on the QCM chip. QCM measurement showed that the resulting MIP film not only had a great affinity towards the template peptide, but also could bind the corresponding gp41 protein specifically. The dissociation constant (Kd) of MIP for the template peptide was calculated to be 3.17 nM through Scatchard analysis, which was similar to those of monoclonal antibodies. Direct detection of the gp41 was achieved quantitatively using the resulting MIP-based biomimetic sensor. The detection limit of gp41 was 2 ng/mL, which was comparable to the reported ELISA method. In addition, the practical analytical performance of the sensor was examined by evaluating the detection of gp41 in human urine samples with satisfactory results.Highlights► Dopamine was used as monomer for protein imprinting based on epitope-imprinting techniques. ► MIP film was coated on the QCM chip due to the adhesiveness of the polydopamine. ► The MIP-coated QCM sensor can recognize template peptide and corresponding protein. ► The detection limit of HIV-1 gp41 protein was 2 ng/mL. ► The MIP-coated QCM sensor was applied for monitoring protein in human urine samples.
Co-reporter:Ting-xiu Ye, Shu-lan Ye, Dong-mei Chen, Qing-ai Chen, Bin Qiu, Xi Chen
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2012 Volume 86() pp:467-471
Publication Date(Web):February 2012
DOI:10.1016/j.saa.2011.10.070
In this study, the noncovalent functionalization of graphene with cationic porphyrins in an aqueous medium was investigated using UV–vis and fluorescence approaches. To characterize the interaction between graphene and cationic porphyrins, 5,10,15,20-tetra (4-pyridyl)-21H,23H-porphine, 5,10,15,20-tetrakis (1-methyl-4-pyridinio) porphyrin tetra (p-toluenesulfonate) and 5,10,15,20-tetrakis (4-trimethylammoniophenyl) porphyrin tetra (p-toluenesulfonate) porphyrin were chosen as reagents. The intermolecular interactions were found to occur immediately after mixing the cationic porphyrins with graphene. The absorption spectra of the cationic porphyrins after mixing with graphene showed distinct red shifts of the Soret and Q-bands compared to free cationic porphyrins indicating that interactions occur between the cationic porphyrins and graphene. A strong fluorescence quenching of the cationic porphyrins in the presence of graphene indicated that efficient electron or energy transfer occurred from the excited state of the cationic porphyrins to graphene. Cationic porphyrins were immobilized on the surface of graphene through electrostatic and π–π stacking interactions, and the chemical shape of graphene played an important role in the intermolecular interactions and the red shift extent of cationic porphyrins is mostly dependent on the functional groups and charges of the graphene surface. The results show that less functional groups on the graphene's surface and edge would lead to stronger π–π stacking interactions between graphene and cationic porphyrins.Graphical abstractHighlights► Three kinds of graphene samples were prepared by different methods. ► The interactions between graphene and cationic porphyrins were investigated. ► The intermolecular interactions are mostly depends on the chemical shape of graphene.
Co-reporter:Zhi-min Cai, Yan-fang Wu, Yun-he Huang, Qiu-ping Li, Xiao-mei Chen, Xi Chen
Talanta 2012 Volume 94() pp:356-360
Publication Date(Web):30 May 2012
DOI:10.1016/j.talanta.2012.03.046
Chitosan, a cationic polysaccharide containing amino and hydroxyl groups, was used to fabricate an electrochemiluminescence (ECL) sensor. In the sensor construction, a glassy carbon electrode (GCE) was first coated by a chitosan film which embedded gold nanoparticles, and then the film was modified by introducing carboxyl groups on the surface, which were used to immobilize tris(2,2′-bipyridyl)ruthenium(II) doped amino-functional silica nanoparticles (NH2–RuSiNPs) through amido links. The successful modification was confirmed by scanning electronic microscopy and cyclic voltammetry. A binding model between the chitosan/nanogold composite film and NH2–RuSiNPs was also proposed, in which the amido link was the dominant bonding, accompanied with hydrogen bond interaction. ECL studies revealed that the sensor had very good response to different concentrations of 2-(dibutylamino) ethanol. This sensor was also applied in methamphetamine determination.Highlights► NH2–RuSiNPs were synthesized by one-pot approach. ► NH2–RuSiNPs were linked to electrode surface by the mediator chitosan. ► The amino link was the dominant interaction on the interface. ► The modified electrode showed good ECL response to 2-(dibutylamino) ethanol.
Co-reporter:Xiaomei Chen ; Genghuang Wu ; Jinmei Chen ; Xi Chen ; Zhaoxiong Xie ;Xiaoru Wang
Journal of the American Chemical Society 2011 Volume 133(Issue 11) pp:3693-3695
Publication Date(Web):February 24, 2011
DOI:10.1021/ja110313d
Ultrafine Pd nanoparticles monodispersed on graphene oxide (GO) surfaces were successfully prepared by the redox reaction between PdCl42− and GO. The as-made catalyst is very “clean” as a result of the surfactant-free formation process, allowing it to express high electrocatalytic ability in formic acid and ethanol oxidation relative to a commercial Pd/C catalyst. This simple and straightforward method is of significance for the facile preparation metal nanocatalysts with high catalytic activity on proper supporting materials.
Co-reporter:Xu-dong Wang, Ting-yao Zhou, Xin-hong Song, Yaqi Jiang, Chaoyong James Yang and Xi Chen
Journal of Materials Chemistry A 2011 vol. 21(Issue 44) pp:17651-17653
Publication Date(Web):06 Oct 2011
DOI:10.1039/C1JM14162G
We fabricated a chameleon cloth which changed its vivid colours at different oxygen concentrations under ultraviolet excitation. Combined with a photographing technique, the chameleon cloth possesses the ability for real-time quantitative imaging of oxygen distribution, which could be used for quick location of dangerous oxygen-deficiencies and oxygen-free regions.
Co-reporter:Chun-Hua Lu, Juan Li, Xiu-Juan Qi, Xiao-Rong Song, Huang-Hao Yang, Xi Chen and Guo-Nan Chen
Journal of Materials Chemistry A 2011 vol. 21(Issue 29) pp:10915-10919
Publication Date(Web):15 Jun 2011
DOI:10.1039/C1JM11121C
In this article, we present a new method for the multiplex detection of nucleases by using graphene oxide (GO) as a platform. We introduce a Y-shaped DNA (Y-DNA) as the multiplex probe. The 5′ termini of the Y-DNA are labeled with carboxy fluorescein (FAM), 6-carboxy-X-rhodamine (ROX) and cyanine 5 (Cy5) and they include three nuclease cleavage sites corresponding to PvuII, EcoRV and HaeIII, respectively. Upon the addition of nucleases, the nucleases cleave the corresponding sites in Y-DNA. Then, short dsDNA fragments containing fluorophores were released from the Y-DNA. These dsDNA fragments were unstable and easy to unwind into two short ssDNAs. They were then adsorbed onto the GO surface. Because of the excellent electronic transference of GO, the fluorescence intensity of the fluorophores can be quenched efficiently. Therefore, by monitoring the fluorophores’ fluorescence change before and after the addition of the nucleases, it is easy to establish a platform of a Y-DNA/GO complex for the simultaneous multiplex detection of nucleases.
Co-reporter:Lan Luan, Zhi-jie Lin, Genghuang Wu, Xiao-li Huang, Zhi-min Cai and Xi Chen
Chemical Communications 2011 vol. 47(Issue 13) pp:3963-3965
Publication Date(Web):21 Feb 2011
DOI:10.1039/C1CC00057H
In this paper, an electrochemiluminescence (ECL) encoding method was developed for the first time, based on a dual-dye system including Ru(bpy)32+ as an ECL emitter and fluorescein isothiocyanate (FITC) as a coding dye.
Co-reporter:Xu-dong Wang, Xin-hong Song, Chun-yan He, Chaoyong James Yang, Guonan Chen, and Xi Chen
Analytical Chemistry 2011 Volume 83(Issue 7) pp:2434
Publication Date(Web):March 4, 2011
DOI:10.1021/ac200196y
Reversible colorimetric temperature nanosensors were prepared using a very simple precipitation method to encapsulate two color luminescent dyes. These nanosensors presented obvious reversible temperature response and enabled both rapid colorimetric temperature estimation using the eyes and quantitative two-dimensional thermo-imaging. Heat-exchange induced fluid motion was, for the first time, rapidly, precisely, and quantitatively imaged by just taking color pictures, and this presented good temporal and spatial resolution for studying heat-driven hydrodynamics. These nanosensors should have great application in micro/nanoscale research and also fabrication into films for macroscopic study.
Co-reporter:Jingbin Zeng, Jing Zou, Xinhong Song, Jinmei Chen, Jiaojiao Ji, Bo Wang, Yiru Wang, Jaeho Ha, Xi Chen
Journal of Chromatography A 2011 Volume 1218(Issue 2) pp:191-196
Publication Date(Web):14 January 2011
DOI:10.1016/j.chroma.2010.11.020
This work describes an electrochemically enhanced solid-phase microextraction (EE-SPME) method using a mild negative potential (−0.6 V) for the enhanced extraction of the selected basic drugs in a pure aqueous matrix and urine samples. The EE-SPME method gave a more effective extraction of drugs (primarily via electrophoresis and complementary charge interaction) compared to that obtained with SPME (without applying a potential, and which is based on passive partitioning). The EE-SPME method eliminated the need for alkalizing, derivatizing the drugs, or modifying the fiber coating before extraction. The analysis of methamphetamine (MA) and amphetamine (AM) was selected as a typical example to demonstrate in detail the advantages of EE-SPME over SPME. Based on the results obtained, 3-min extraction efficiency for both the amphetamines using EE-SPME was better than that of 30-min using SPME. The developed EE-SPME–GC method exhibited wide linear ranges (2–1000 ng mL−1) for both the amphetamines with R2 larger than 0.99, and the method detection limits (MDLs) for AM and MA were 0.26 and 0.12 ng mL−1, respectively. In addition, the EE-SPME method developed was also successfully applied to enhance the extraction of several other basic drugs (ephedrine, 3,4-methylenedioxyamphetamine (MDA), atropine, methadone, cocaine, codeine, acetylcodeine and papaverine) with preconcentration factors from 157 to 2199, indicating the potential applicability of this method in the field of forensic, clinical and pharmaceutical analysis.
Co-reporter:Xiao-mei Chen, Geng-huang Wu, Ya-qi Jiang, Yi-ru Wang and Xi Chen
Analyst 2011 vol. 136(Issue 22) pp:4631-4640
Publication Date(Web):05 Oct 2011
DOI:10.1039/C1AN15661F
Similar to its popular older cousins of fullerene and carbon nanotubes (CNTs), the latest form of nanocarbon, graphene, is inspiring intensive research efforts in its own right. As an atomically thin layer of sp2-hybridized carbon, graphene possesses spectacular electronic, optical, magnetic, thermal and mechanical properties, which make it an exciting material in a variety of important applications. In this review, we present the current advances in the field of graphene electroanalytical chemistry, including the modern methods of graphene production, and graphene functionalization. Electrochemical (bio) sensing developments using graphene and graphene-based materials are summarized in more detail, and we also speculate on their future and discuss potential progress for their applications in electroanalytical chemistry.
Co-reporter:Mei-Jin Li, Pengchong Jiao, Min Lin, Weiwen He, Guo-Nan Chen and Xi Chen
Analyst 2011 vol. 136(Issue 1) pp:205-210
Publication Date(Web):13 Oct 2010
DOI:10.1039/C0AN00444H
A new water-soluble iridium(III) diimine complex with appended sugar was synthesized and characterized. The electrochemiluminescent behavior of the new complex in aqueous buffer was first studied and the ECL signal was found to be much higher than that of [Ru(bpy)3]2+ at a Pt working electrode. Tri-n-propylamine (TPA) and antibiotics were determined by the ECL of the iridium(III) complex in aqueous buffer at the Pt electrode and the method was found to show good sensitivity and reproducibility. The new iridium(III) complex was found to display good solubility in aqueous solution and a strong ECL signal at the Pt electrode, which might open up the possibility of its application in analysis.
Co-reporter:Jing Zou;Xinhong Song;Jiaojiao Ji;Weici Xu;Jinmei Chen;Yaqi Jiang;Yiru Wang
Journal of Separation Science 2011 Volume 34( Issue 19) pp:2765-2772
Publication Date(Web):
DOI:10.1002/jssc.201100303
Abstract
A polypyrrole (Ppy)/graphene (G) composite was developed and applied as a novel coating for use in solid-phase microextraction (SPME) coupled with gas chromatography (GC). The Ppy/G-coated fiber was prepared by electrochemically polymerizing pyrrole and G on a stainless-steel wire. The extraction efficiency of Ppy/G-coated fiber for five phenols was the highest compared with the fibers coated with either Ppy or Ppy/graphene oxide (GO) using the same method preparation. Significantly, compared with various commercial fibers, the extraction efficiency of Ppy/G-coated fiber is better than or comparable to 85 μm CAR/PDMS fiber (best extraction efficiency of phenol, o-cresol, and m-cresol in commercial fibers) and 85 μm polyacrylate (PA) fiber (best extraction efficiency of 2,4-dichlorophenol and p-bromophenol in commercial fibers). The effects of extraction and desorption parameters such as extraction time, stirring rate, and desorption temperature and time on the extraction/desorption efficiency were investigated and optimized. The calibration curves were linear from 10 to 1000 μg/L for o-cresol, m-cresol, p-bromophenol, and 2,4-dichlorophenol, and from 50 to 1000 μg/L for phenol. The detection limits were within the range 0.34–3.4 μg/L. The single fiber and fiber-to-fiber reproducibilities were <8.3 (n=7) and 13.3% (n=4), respectively. The recovery of the phenols spiked in natural water samples at 200 μg/L ranged from 74.1 to 103.9% and the relative standard deviations were <3.7%.
Co-reporter:Mei-Jin Li, Chong-Qing Zhan, Mei-Juan Nie, Guo-Nan Chen, Xi Chen
Journal of Inorganic Biochemistry 2011 Volume 105(Issue 3) pp:420-425
Publication Date(Web):March 2011
DOI:10.1016/j.jinorgbio.2010.12.007
A series of the new ruthenium(II) complexes with different number of aldehyde groups have been synthesized and characterized for the simple and selective sensing of homocysteine (Hcy) and cysteine (Cys). The reaction of these ruthenium(II) complexes with Hcy and Cys afforded thiazinane or thiazolidine derivatives which resulted in the obvious changes in the UV–visible spectra and strong enhancement of the luminescence intensity of the system. The luminescence enhancement of [Ru(dmb)2(L2)]2+ (dmb: 4,4′-dimethyl-2,2′-bipyridine) showed a good linearity in the concentration of 4.2–350 μM and 6–385 μM with the detection limits of 0.3 μM and 1 μM for Hcy and Cys, respectively. The absorption and emission bands from metal-to-ligand charge transfer transition in the visible region and the large Stokes shift of the ruthenium(II) complex chromophore made it suitable for biological applications.
Co-reporter:Qingai Chen, Tingyao Zhou, Chunyan He, Yaqi Jiang and Xi Chen
Analytical Methods 2011 vol. 3(Issue 7) pp:1471-1474
Publication Date(Web):21 Jun 2011
DOI:10.1039/C1AY05023K
In this study, a rapid, convenient and in situ applicable Cu2+ sensor was constructed based on a luminescent layer immobilizing Ru(bpy)3Cl2 with a maximum wavelength of 600 nm, which was taken as the reference background light. The luminescence intensity of the layer was kept constant and isolated from the oxygen change in the solution due to the hybrid polyacrylonitrile–dimethylsulfoxide used in the immobilization of the Ru(bpy)3Cl2. The CdTe quantum dot (QD) luminescence, with a maximum wavelength of 520 nm, was quenched to different degrees depending on the Cu2+ concentration in the solution. Using a commercial camera, different colors could be captured in different Cu2+ concentrations. This color change was caused by the composite light with stable luminescence from the Ru(bpy)3Cl2 layer and the changeable fluorescence of the CdTe QDs. Sensor characteristics, including the co-existing ions, oxygen content, temperature effect, and sensor stability, were investigated.
Co-reporter:Guo Guangmei, Zhijie Lin and Xi Chen
Analytical Methods 2011 vol. 3(Issue 1) pp:53-55
Publication Date(Web):08 Dec 2010
DOI:10.1039/C0AY00620C
In order to use a water soluble organic electrochemiluminescence (ECL) reagent in an aqueous medium, a simple one-pot method was developed to synthesize 9,10-diphenylanthracene (9,10-DPA) doped polystyrene beads based on dispersion polymerization. The bead size was around 3 μm and they were well dispersed. Fluorescence experiments showed that the polystyrene beads were successfully doped in 9,10-DPA. The 9,10-DPA doped beads were then used in ECL studies, and they retained their ECL activity well. The results imply that polystyrene beads could be a suitable platform leading to the application of hydrophobic ECL reagents in aqueous media.
Co-reporter:Yun Zhao;Tingxiu Ye;Haixu Chen;Dapeng Huang;Tingyao Zhou;Chunyan He
Luminescence 2011 Volume 26( Issue 1) pp:29-34
Publication Date(Web):
DOI:10.1002/bio.1182
Abstract
A new functional fluorinated material taking n-propyltrimethoxysilicane (n-propyl-TriMOS) and 3,3,3-trifluoropropyltrimethoxysilicane (TFP-TriMOS) as precursors was applied to construct a novel dissolved oxygen sensing film. The sensing film was fabricated by dip-coating the functional fluorinated material-doped [meso-tetrakis(pentafluorophenyl) porphyinato] platinum(II) (PtF20TPP) onto a glass slide. The oxygen sensing film exhibited a good linear relationship, fast response time, long stability and high sensitivity to dissolved oxygen. In the developed optical oxygen sensor, an LED and a photodiode were composed to construct a back-detection optical system not needing an optical fiber based on fluorescence intensity detection. The smart optical oxygen sensor based on the PtF20TPP fluorescence quenching possesses the advantages of portability and low cost and can be applied to the dissolved oxygen in situ monitoring in seawater. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:GuangMei Guo;QingAi Chen
Science China Chemistry 2011 Volume 54( Issue 11) pp:1777-1781
Publication Date(Web):2011 November
DOI:10.1007/s11426-011-4389-5
A novel electrochemiluminescence (ECL) sensing approach was developed for glucose detection based on crosslinking Ru(bpy)3Cl2-doped silica nanoparticles (RuSiNPs) with glucose dehydrogenase on a glassy carbon electrode (GCE). Glutaraldehyde and aminopropyltrimethoxysilane were used as linking agents, and chitosan was used to immobilize the composites onto the GCE surface. The ECL sensor presented good characteristics in terms of stability and reproducibility. Under optimized conditions, the linear response of ECL intensity to glucose concentration was valid in the range of 0.2 to 20 mmol/L (R2 = 0.9962). The application results indicated that the proposed approach is with great potential in the determination of glucose.
Co-reporter:Liangbi Chen, Wenfeng Chen, Chunhua Ma, Dan Du, Xi Chen
Talanta 2011 Volume 84(Issue 1) pp:104-108
Publication Date(Web):15 March 2011
DOI:10.1016/j.talanta.2010.12.027
A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes/polypyrrole (MWCNTs/Ppy) was prepared with an electrochemical method and used for the extraction of pyrethroids in natural water samples. The results showed that the MWCNTs/Ppy coated fiber had high organic stability, and remarkable acid and alkali resistance. In addition, the MWCNTs/Ppy coated fiber was more effective and superior to commercial PDMS and PDMS/DVD fibers in extracting pyrethroids in natural water samples. Under optimized conditions, the calibration curves were found to be linear from 0.001 to 10 μg mL−1 for five of the six pyrethroids studied, the exception being fenvalerate (which was from 0.005 to 10 μg mL−1), and detection limits were within the range 0.12–0.43 ng mL−1. The recoveries of the pyrethroids spiked in water samples at 10 ng mL−1 ranged from 83 to 112%.
Co-reporter:Jinmei Chen, Jing Zou, Jingbin Zeng, Xinhong Song, Jiaojiao Ji, Yiru Wang, Jaeho Ha, Xi Chen
Analytica Chimica Acta 2010 Volume 678(Issue 1) pp:44-49
Publication Date(Web):23 September 2010
DOI:10.1016/j.aca.2010.08.008
In this paper, a novel graphene (G) based solid-phase microextraction (SPME) fiber was firstly prepared by immobilizing the synthesized G on stainless steel wire as coating. The new fiber possessed a homogeneous, porous and wrinkled surface and showed excellent thermal (over 330 °C), chemical and mechanical stability, and long lifespan (over 250 extractions). The SPME performance of the G-coated fiber was evaluated in detail through extraction of six pyrethroid pesticides. Although the thickness of G-coated fiber was only 6–8 μm, its extraction efficiencies were higher than those of two commercial fibers (PDMS, 100 μm; PDMS/DVB, 65 μm). This high extraction efficiency may be mainly attributed to huge delocalized π-electron system of G, which shows strong π-stacking interaction with pyrethroid pesticide. The G-coated fiber was applied in the gas chromatographic determination of six pyrethroids, and their limits of detection were found to be ranged from 3.69 to 69.4 ng L−1. The reproducibility for each single fiber was evaluated and the relative standard deviations (RSDs) were calculated to be in the range from 1.9% to 6.5%. The repeatability of fiber-to-fiber and batch-to-batch was 4.3–9.2% and 4.1–9.9%. The method developed was successfully applied to three pond water samples, and the recoveries were 83–110% at a spiking of 1 μg L−1.
Co-reporter:Meihua Liu, Meijin Li, Bin Qiu, Xi Chen, Guonan Chen
Analytica Chimica Acta 2010 Volume 663(Issue 1) pp:33-38
Publication Date(Web):17 March 2010
DOI:10.1016/j.aca.2010.01.027
A novel molecularly imprinted polymer-coated polypropylene hollow fiber tube (MIP-HFT) was photoinitiated for the copolymerization of diethylstilbestrol (DES) as a template molecule, α-methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a crosslinking agent. The characteristics and applications of the MIP-HFT were investigated. In order to compare its characteristics with those of a non-imprinted polymer-immersed hollow fiber tube, the selectivity of the MIP-HFT was investigated using dienestrol and hexestrol as the structural analogues of a DES template, and phenol and methylbenzene were taken as reference compounds. The MIP-HFT was employed in the HPLC analysis of spiked milk samples. The detection limits of the method were found to be in the range 2.5–3.3 μg L−1 for DES, dienestrol and hexestrol and the RSD% were in the range 6.4–8.9. The limits of quantitation were found to be in the range 8.7–9.4 μg L−1 in milk for DES, dienestrol and hexestrol, and their average recoveries were 83.7–90.6% in the spiked milk samples. The experimental results revealed that the MIP-HFT provides a good carrier for the selective adsorption of DES and its chemical structure analogs, and can be used for the preconcentration of these compounds in complicated samples.
Co-reporter:Jingbin Zeng, Jinmei Chen, Xinhong Song, Yiru Wang, Jaeho Ha, Xi Chen, Xiaoru Wang
Journal of Chromatography A 2010 Volume 1217(Issue 11) pp:1735-1741
Publication Date(Web):12 March 2010
DOI:10.1016/j.chroma.2010.01.034
In this paper, we proposed an approach using a multi-walled carbon nanotubes (MWCNTs)/Nafion composite coating as a working electrode for the electrochemically enhanced solid-phase microextraction (EE-SPME) of charged compounds. Suitable negative and positive potentials were applied to enhance the extraction of cationic (protonated amines) and anionic compounds (deprotonated carboxylic acids) in aqueous solutions, respectively. Compared to the direct SPME mode (DI-SPME) (without applying potential), the EE-SPME presented more effective and selective extraction of charged analytes primarily via electrophoresis and complementary charge interaction. The experimental parameters relating to extraction efficiency of the EE-SPME such as applied potentials, extraction time, ionic strength, sample pH were studied and optimized. The linear dynamic range of developed EE-SPME-GC for the selected amines spanned three orders of magnitude (0.005–1 μg mL−1) with R2 larger than 0.9933, and the limits of detection were in the range of 0.048–0.070 ng mL−1. All of these characteristics demonstrate that the proposed MWCNTs/Nafion EE-SPME is an efficient, flexible and versatile sampling and extraction tool which is ideally suited for use with chromatographic methods.
Co-reporter:Xiao-Mei Chen, Geng-Huang Wu, Jin-Mei Chen, Ya-Qi Jiang, Guo-Nan Chen, Munetaka Oyama, Xi Chen, Xiao-Ru Wang
Biosensors and Bioelectronics 2010 Volume 26(Issue 2) pp:872-876
Publication Date(Web):15 October 2010
DOI:10.1016/j.bios.2010.07.083
This communication reports a novel electrochemiluminescence (ECL) sensor based on covalently linking bis(2,2′-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) (Ru(II)-NH2) with graphite oxide (GO) on a glassy carbon electrode. 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride and N-hydroxy-succinimide were applied to activate the carboxyl groups on the GO surface and catalyze the formation of amido link between Ru(II)-NH2 and carboxyl groups on GO. The composite film was characterized using atomic force microscopy, transmission electron microscopy and Fourier transform infrared absorption spectroscopy. Based on ECL experimental results, the composite film modified electrode displayed high electrochemical activity towards the oxidation of 2-(dibutylamino) ethanol (DBAE). Under optimized conditions, the linear response of ECL intensity to DBAE concentration was valid in the range 6.0 × 10−7–2.0 × 10−4 mol L−1 (r2 = 0.9948) with a detection limit (S/N = 3) of 5.0 × 10−8 mol L−1. Furthermore, the ECL sensor presented good characteristics in terms of stability and reproducibility, promising the development of ECL sensors for biologically important compounds.
Co-reporter:Haizhu Liu, Ping Yu, Dan Du, Chunyan He, Bin Qiu, Xi Chen, Guonan Chen
Talanta 2010 Volume 81(1–2) pp:433-437
Publication Date(Web):15 April 2010
DOI:10.1016/j.talanta.2009.12.020
Novel ratiometric fluorescent silica nanoparticles with high selectivity towards Hg2+ were synthesized for the detection of Hg2+. Hg2+ promoted the ring opening of spirolactam in the rhodamine moiety grafted onto the silica nanoparticles, resulting in a change in the fluorescence intensity. The fluorescence intensity was proportional to the Hg2+ concentration, and the detection limit (S/N = 3) for Hg2+ was found to be 2.59 × 10−9 mol L−1 with a linear range from 0.4 to 8 × 10−7 mol L−1. In addition, the morphology of the silica nanoparticles, the effects of pH and co-existing substances, and the reversibility were investigated. The proposed approach was successfully applied to the determination of Hg2+ in water samples.
Co-reporter:Xiao-mei Chen, Zhi-jie Lin, De-Jun Chen, Tian-tian Jia, Zhi-min Cai, Xiao-ru Wang, Xi Chen, Guo-nan Chen, Munetaka Oyama
Biosensors and Bioelectronics 2010 Volume 25(Issue 7) pp:1803-1808
Publication Date(Web):15 March 2010
DOI:10.1016/j.bios.2009.12.035
A nonenzymatic electrochemical method was developed for glucose detection using an electrode modified with palladium nanoparticles (PdNPs)-functional carbon nanotubes (FCNTs). PdNPs were homogeneously modified on FCNTs through a facile spontaneous redox reaction and characterized by transmission electron microscopy. Based on the voltammetric and amperometric results, PdNPs efficiently catalyzed the oxidation of glucose at 0.40 V in the presence of 0.2 M NaCl and showed excellent resistance towards poisoning from such interfering species as ascorbic acid, uric acid, and p-acetamidophenol. This anti-poisoning ability was investigated using analysis of the electrocatalytic products by in situ subtractively normalized interfacial Fourier transform infrared reflection spectroscopy, and the results indicated that no strongly adsorbed COad species could be found in the oxidation products, which was obviously different from the results obtained using Pt-based electrodes. In order to verify the sensor reliability, it was applied to the determination of glucose in urine samples. The results indicated that the proposed approach provided a highly sensitive, wide linear range, more facile method with good reproducibility for glucose determination, promising the development of Pd-based material in nonenzymatic glucose sensing.
Co-reporter:Hai-xu Chen, Xu-dong Wang, Xin-hong Song, Ting-yao Zhou, Ya-qi Jiang, Xi Chen
Sensors and Actuators B: Chemical 2010 Volume 146(Issue 1) pp:278-282
Publication Date(Web):8 April 2010
DOI:10.1016/j.snb.2010.01.068
Utilizing a dual color design, a rapid, convenient and in situ applicable pH sensor was constructed based on a dual light-emitting diode (LED) system. One LED lamp with a maximum emission wavelength of 465 nm was used to excite the pH fluorescent indicator, 5(6)-carboxyfluorescein (CF), and the other LED lamp with red color emission (λmax 660 nm) was selected to supply a stable color background (the reference light). The dual light from the fluorescent emission of CF and the background light were captured using a commercial charge coupled device camera. Under constant and stable background light, the change of the CF fluorescence intensity in solutions at different pH values appeared as different colors. The sensor characteristics, including the effects of temperature, co-existing ions, and the sample analysis performance, were investigated.
Co-reporter:Chun-Hua Lu;Juan Li;Jing-Jing Liu;Huang-Hao Yang Dr. Dr.;Guo-Nan Chen Dr.
Chemistry - A European Journal 2010 Volume 16( Issue 16) pp:4889-4894
Publication Date(Web):
DOI:10.1002/chem.200903071
Abstract
Here, we report a novel, highly sensitive, selective and economical molecular beacon using graphene oxide as the “nanoquencher”. This novel molecular beacon system contains a hairpin-structured fluorophore-labeled oligonucleotide and a graphene oxide sheet. The strong interaction between hairpin-structured oligonucleotide and graphene oxide keep them in close proximity, facilitating the fluorescence quenching of the fluorophore by graphene oxide. In the presence of a complementary target DNA, the binding between hairpin-structured oligonucleotide and target DNA will disturb the interaction between hairpin-structured oligonucleotide and graphene oxide, and release the oligonucleotide from graphene oxide, resulting in restoration of fluorophore fluorescence. In the present study, we show that this novel graphene oxide quenched molecular beacon can be used to detect target DNA with higher sensitivity and single-base mismatch selectivity compared to the conventional molecular beacon.
Co-reporter:Zhimin Cai;Zhijie Lin;Xiaomei Chen;Tiantian Jia;Ping Yu
Luminescence 2010 Volume 25( Issue 5) pp:367-372
Publication Date(Web):
DOI:10.1002/bio.1160
Abstract
An electrochemiluminescence (ECL) approach for methamphetamine determination was developed based on a glassy carbon electrode modified with a Ru(bpy)32+-doped silica nanoparticles/Nafion composite film. The monodispersed nanoparticles, which were about 50 nm in size, were synthesized using the water-in-oil microemulsion method. The ECL results revealed that Ru(bpy)32+ doped in silica nanoparticles retained its original photo- and electrochemical properties. The ECL intensity was found to be proportional to methamphetamine concentration over the range from 1.0 × 10−7 to 1.0 × 10−5 mol L−1, and the detection limit was found to be 2.6 × 10−8 mol L−1. The proposed ECL approach was used to analyze the methamphetamine content in drugs. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Maosheng Zhang, Jiarong Huang, Ping Yu, Xi Chen
Talanta 2010 Volume 81(1–2) pp:162-166
Publication Date(Web):15 April 2010
DOI:10.1016/j.talanta.2009.11.052
A novel protein molecularly imprinted membrane (PMIM) was synthesized on the surface of multiwalled carbon nanotubes (MWNTs) through a surface molecular imprinting technique by using bovine serum albumin (BSA) as the template molecule, acrylamide (AAm) as the functional monomer, N,N′-methylenebisacrylamide (NNMBA) as the cross-linker and ammonium persulphate [(NH4)2S2O8] as the initiator. The amounts of raw materials were optimized in this paper and the suitable amount is 0.1 g of CNTs, 0.02 g of BSA, 0.24 g of AAm, 0.1 g of MBA and 0.025 mg of (NH4)2S2O8. The selective recognition ability of PMIM/MWNTs was evaluated using adsorption experiments. Maximum adsorption capacity was 5.53 μg/mg PMIM/MWNTs and a saturation value was achieved at a BSA concentration of 0.2 mg/mL. The selectivity adsorption experiments showed that the PMIM/MWNTs also had higher adsorption capacities for BSA than for such molecules, as HSA, HB, pepsin and HRP. The PMIM/MWNTs displayed a 2.6-fold increase in affinity to BSA compared to the nPMIM/MWNTs. The PMIM/MWNTs, on the other hand, did not exhibit any significant change in affinity to other molecules compared to the nPMIM/MWNTs. In the experiment, the characteristics of the PMIM/MWNTs were analyzed using infrared spectroscopy and their configurations were observed using scanning electron microscopy.
Co-reporter:Zhi-jie Lin, Xiao-mei Chen, Tian-tian Jia, Xu-dong Wang, Zhao-xiong Xie, Munetaka Oyama and Xi Chen
Analytical Chemistry 2009 Volume 81(Issue 2) pp:830
Publication Date(Web):December 9, 2008
DOI:10.1021/ac8020054
A colorimetric electrochemiluminescence (ECL) sensor was fabricated for the first time, based on a dual-color system including a strong red Ru(bpy)32+ ECL and a green reference light from a light emitting diode. Traditional ECL intensity information can be easily transformed into a color variation with this sensor, and the color variation can be directly monitored using the naked eye or a commercial CCD camera. The sensor has been successfully used to determine the concentration of tripropylamine, proline (enhancing system), and dopamine (quenching system). The results indicated that the color variation obtained corresponded to the concentration of target analytes. This sensor has potential application in rapid and semiquantitative ECL analysis.
Co-reporter:Xiao-mei Chen, Zhi-jie Lin, Tian-tian Jia, Zhi-min Cai, Xiao-li Huang, Ya-qi Jiang, Xi Chen, Guo-nan Chen
Analytica Chimica Acta 2009 Volume 650(Issue 1) pp:54-58
Publication Date(Web):14 September 2009
DOI:10.1016/j.aca.2009.02.035
In this study, a novel material, palladium nanoparticles–carboxylic functional carbon nanotubes (PdNPs–CFCNTs), based on PdNPs supported on CFCNTs was synthesized by a facile spontaneous redox method. The material reveals high electrochemical activity and excellent catalytic characteristic for alcohol electrooxidation on a glassy carbon electrode (GCE) in an alkaline medium. The preparation mechanism was studied by the galvanic cell effect between PdCl42− and functional defect sites on CFCNTs. Results from UV–visible absorption spectroscopy and electrochemical impedance spectroscopy revealed that the reduction of PdCl42− to metallic Pd was successfully achieved. Morphologies of PdNPs supporting on CFCNTs (PdNPs–CFCNTs) were also characterized by transmission electron micrograph. PdNPs–CFCNTs with the best electrocatalytic characteristics were obtained under the condition as: the weight ratio of Pd to CFCNTs was kept at 2:1, the temperature was kept at 70 °C in the synthesis, and the scan rate of the applied potential was selected at 60 mV s−1. The results indicate that PdNPs–CFCNTs could be a great potential material in direct ethanol fuel cells and ethanol sensors.
Co-reporter:Wenfeng Chen, Jingbin Zeng, Jinmei Chen, Xiaoli Huang, Yaqi Jiang, Yiru Wang, Xi Chen
Journal of Chromatography A 2009 Volume 1216(Issue 52) pp:9143-9148
Publication Date(Web):25 December 2009
DOI:10.1016/j.chroma.2009.07.025
A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes (MWCNTs)/Nafion was developed and applied for the extraction of polar aromatic compounds (PACs) in natural water samples. The characteristics and the application of this fiber were investigated. Electron microscope photographs indicated that the MWCNTs/Nafion coating with average thickness of 12.5 μm was homogeneous and porous. The MWCNTs/Nafion coated fiber exhibited higher extraction efficiency towards polar aromatic compounds compared to an 85 μm commercial PA fiber. SPME experimental conditions, such as fiber coating, extraction time, stirring rate, desorption temperature and desorption time, were optimized in order to improve the extraction efficiency. The calibration curves were linear from 0.01 to 10 μg mL−1 for five PACs studied except p-nitroaniline (from 0.005 to 10 μg mL−1) and m-cresol (from 0.001 to 10 μg mL−1), and detection limits were within the range of 0.03–0.57 ng mL−1. Single fiber and fiber-to-fiber reproducibility were less than 7.5 (n = 7) and 10.0% (n = 5), respectively. The recovery of the PACs spiked in natural water samples at 1 μg mL−1 ranged from 83.3 to 106.0%.
Co-reporter:Lifen GONG;Jing ZOU;Jinbin ZENG;Wenfeng CHEN;Xiaoru WANG
Chinese Journal of Chemistry 2009 Volume 27( Issue 1) pp:88-92
Publication Date(Web):
DOI:10.1002/cjoc.200990031
Abstract
Boric and cerous co-doped nano titanium dioxide (B/Ce co-doped TiO2) was synthesized using a sol-gel technique, which involved the hydrolyzation of tetrabutyl titanate with the addition of boric acid and cerous nitrate. The B/Ce co-doped TiO2 was employed for the photocatalytic degradation of dicofol, cyfluthrin and fenvalerate under light irradiation. XRD, TEM, FT-IR and UV-Vis DRS methods were used to characterize the crystalline structure. Experimental results showed that only the anatase signal phase was found for B/Ce co-doped TiO2, but multiplicate phases, including anatase, rutile and less brookite phases, were identified both in the pure TiO2 nanoparticles and Ce-doped TiO2 nanoparticles. The band gap value of B/Ce co-doped nano TiO2 was narrower than that of undoped nano TiO2. Compared to undoped TiO2, a stronger absorption in the range of 420 to 850 nm was found for B/Ce co-doped nano TiO2, which presented a higher photocatalytic activity in the degradation of dicofol, cyfluthrin and fenvalerate than both Ce doped nano TiO2 and pure nano TiO2 under the same light irradiation.
Co-reporter:Xiao-mei Chen, Zhi-min Cai, Zhi-jie Lin, Tian-tian Jia, Hai-zhu Liu, Ya-qi Jiang, Xi Chen
Biosensors and Bioelectronics 2009 Volume 24(Issue 12) pp:3475-3480
Publication Date(Web):15 August 2009
DOI:10.1016/j.bios.2009.04.046
A novel non-enzymatic electrochemiluminescence (ECL) sensor based on palladium nanoparticles (PdNPs)–functional carbon nanotubes (FCNTs) was discovered for glucose detection. PdNPs were homogeneously modified on FCNTs using a facile spontaneous redox reaction method. Their morphologies were characterized by transmission electron microscopy (TEM). Based on ECL experimental results, the PdNPs–FCNTs–Nafion film modified electrode displayed high electrocatalytic activity towards the oxidation of glucose. The free radicals generated by the glucose oxidation reacted with the luminol anion (LH−), and enhanced the ECL signal. Under the optimized conditions, the linear response of ECL intensity to glucose concentration was valid in the range from 0.5 to 40 μmol L−1 (r2 = 0.9974) with a detection limit (S/N = 3) of 0.09 μmol L−1. In addition, the modified electrode presented high resistance towards the poisoning of chloride ion, high selectivity and long-term stability. In order to verify the sensor reliability, it was applied to the determination of glucose in glucose injection samples. The results indicated that the proposed approach provided a highly sensitive, more facile method with good reproducibility for glucose determination, promising the development of a non-enzymatic ECL glucose sensor.
Co-reporter:Tian-tian Jia, Zhi-min Cai, Xiao-mei Chen, Zhi-jie Lin, Xiao-li Huang, Xi Chen, Guo-nan Chen
Biosensors and Bioelectronics 2009 Volume 25(Issue 1) pp:263-267
Publication Date(Web):15 September 2009
DOI:10.1016/j.bios.2009.06.030
An ethanol biosensor, based on the electrogenerated chemiluminescence of Ru(bpy)32+-doped silica nanoparticles (RuSiNPs), was investigated in this study. The biosensor was a modified glassy carbon electrode, where alcohol dehydrogenase was crosslinked to RuSiNPs, and then immobilized on the electrode surface using chitosan. The results indicated that the biosensor exhibited excellent performance during ethanol determination with a wide linear range (10−7 to 10−2 M), low detection limit (5.0 × 10−8 M) and good stability.
Co-reporter:Jingbin Zeng, Jinmei Chen, Liangbi Chen, Yiru Wang, Wenfeng Chen, Xiaoli Huang, Xi Chen
Analytica Chimica Acta 2009 648(2) pp: 194-199
Publication Date(Web):
DOI:10.1016/j.aca.2009.07.008
Co-reporter:HaiLing Chen;Li Zhao;ZhiXia Zhuang
Science China Chemistry 2009 Volume 52( Issue 8) pp:1128-1135
Publication Date(Web):2009 August
DOI:10.1007/s11426-009-0146-4
An amperometric glucose biosensor was developed based on the immobilization of glucose oxidase in the organically modified silicate (ormosil)-polyvinyl acetate (PVA) matrix onto a Prussian Blue (PB)-modified glassy carbon electrode. A higher stability PB-modified electrode was prepared by the electrochemical deposition of FeCl3, K3[Fe(CN)6] and ethylenediamine tetraacetic acid (EDTA) under cyclic voltammetric (CV) conditions. The effects of the potential range of CV conditions, electrolyte cations, applied potential, pH, temperature and co-existing substances were investigated. The detection limit of the glucose biosensor was 8.1 μmol·L−1 (S/N = 3) with a linear range from 20 μmol·L−1 to 2 mmol·L−1 (R = 0.9965). The biosensor presented a fast response and good selectivity. Additionally, excellent reproducibility and stability of the biosensor were observed.
Co-reporter:Guangmei Guo, Binbin Yu, Ping Yu, Xi Chen
Talanta 2009 Volume 79(Issue 3) pp:570-575
Publication Date(Web):15 August 2009
DOI:10.1016/j.talanta.2009.04.036
TiO2- and Ag/TiO2-nanotubes (NTs) were synthesized by hydrothermal methods and microwave-assisted preparation, respectively. Scanning electron microscopy, high resolution transmission electron microscopy, Brunauer–Emmett–Teller particle surface area measurement and X-ray diffraction were used to characterize the nanotubes. Rutile TiO2-NTs with Na2Ti5O11 crystallinity had a length range of 200–400 nm and diameters of 10–20 nm. TiO2- and Ag/TiO2-NTs with a 0.4% deposition of Ag had high surface areas of 270 and 169 m2 g−1, respectively. The evaluation of photocatalytic activity showed that Ag/TiO2-NTs displayed higher photocatalytic activity than pure TiO2-NTs and a 60.91% degradation of Rhodamine-B with 0.8% deposition of Ag species. Also 60% of Rhodamine-6G was physisorbed and 40% chemisorbed on the surface of TiO2-NTs. In addition, the photocatalytic degradations of organochlorine pesticides taking α-hexachlorobenzene (BHC) and dicofol as typical examples, were compared using Ag/TiO2-NTs, and found that their degradations rates were all higher than those obtained from commercial TiO2.
Co-reporter:Xu-dong Wang, Hai-xu Chen, Ting-yao Zhou, Zhi-jie Lin, Jing-bin Zeng, Zhao-xiong Xie, Xi Chen, Kwok-yin Wong, Guo-nan Chen, Xiao-ru Wang
Biosensors and Bioelectronics 2009 Volume 24(Issue 12) pp:3702-3705
Publication Date(Web):15 August 2009
DOI:10.1016/j.bios.2009.05.018
A novel direct readout colorimetric optical glucose sensor strip was constructed based on a three-layer film, including a green-emitted CdTe/CdS quantum dots (QDs) layer as a stable color background, a red-fluorescent platinum-porphyrin oxygen-sensing layer and a glucose oxidase layer. The sensor achieved high resolution (up to 0.2 mmol L−1) glucose determination with a detection range from 0 to 3.0 mmol L−1. A “glucose ruler” which acts as a glucose standard colorimetric card was obtained. Glucose concentration could easily be directly readout using the “glucose ruler”, which made the glucose determination rapid, convenient and easy. The effects of pH, salinity and temperature were systematically investigated. The prepared sensor was finally applied for glucose sample analysis, compared with the “glucose ruler”, accurate results could be directly readout.
Co-reporter:Jingbin Zeng, Jinmei Chen, Zequan Lin, Wenfeng Chen, Xi Chen, Xiaoru Wang
Analytica Chimica Acta 2008 Volume 619(Issue 1) pp:59-66
Publication Date(Web):30 June 2008
DOI:10.1016/j.aca.2008.02.013
An approach to the synthesis of hydroxyl-terminated polymethylphenylsiloxane (PMPS-OH) was proposed and the synthesized PMPS-OH was successfully applied as a precursor to prepare a novel coating for solid-phase microextraction (SPME) via the sol–gel process. The thickness and length of the prepared coating was 70 μm and 1.5 cm, respectively. The extraction efficiency of the PMPS-coated fiber for selected pesticides was higher than that of commercial fibers including 100 μm polydimethylsiloxane (PDMS), 85 μm polyacrylate (PA) and 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB). The influence of the extraction process, extraction temperature, extraction time, stirring rate, ionic strength, GC inlet conditions, desorption temperature and time for PMPS-coated fiber application was studied and optimized. Several experiments were carried out to evaluate the analytical characteristics of the proposed SPME–GC-ECD method under optimized conditions. The linearity was from 0.5 to 100 ng g−1 for p,p′-DDE, p,p′-DDD and bifenthrin, and from 2 to 100 ng g−1 for o,p′-DDT, p,p′-DDT, fenpropathrin, beta-cyfluthrin and cyhalothrin. The detection limits of these pesticides were between 0.13 and 1.45 ng g−1. The recovery of the pesticides spiked in various vegetables at 4 ng g−1 ranged from 42.9% to 105.3%, and the relative standard deviations were less than 16.2%.
Co-reporter:Hailing Chen, Tingxiu Ye, Bin Qiu, Guonan Chen, Xi Chen
Analytica Chimica Acta 2008 Volume 612(Issue 1) pp:75-82
Publication Date(Web):31 March 2008
DOI:10.1016/j.aca.2008.02.006
A novel biochemical oxygen demand (BOD) sensing method employing a ferricyanide (FC) mediator immobilized in an ion-exchangeable polysiloxane was developed. The ion-exchangeable polysiloxane containing alkylammonium groups (PAPS-Cl) was synthesized by sol–gel reaction of 3-(aminopropyl)trimethoxysilane (APTMOS) catalyzed by hydrochloric acid. FC was combined in PAPS-Cl via ion-association and the product was labeled as PAPS-FC, which was employed for a modified glassy carbon electrode. The apparent diffusion coefficient (Dapp) of FC on the modified glassy carbon electrode was 9.8 × 10−11 cm2 s−1. In a three-electrode system, a linear relationship between the anodic current responses and glucose/glutamate (GGA) concentration was obtained up to 40 mg O2 L−1 (r = 0.994) when the reaction mixture was incubated for 30 min. Single sensor and piece-to-piece reproducibility were less than 3.8 and 7.7%, respectively. The effects of dissolved oxygen, pH, temperature and co-existing substances on the BOD responses were studied. The sensor responses to nine pure organic substances were compared with the conventional BOD5 method and other biosensor methods. Detection results of seawater samples were compared with those obtained from the BOD5 method and showed a good correlation (r = 0.988).
Co-reporter:Jingbin Zeng, Jinmei Chen, Yiru Wang, Wenfeng Chen, Xi Chen, Xiaoru Wang
Journal of Chromatography A 2008 Volume 1208(1–2) pp:34-41
Publication Date(Web):24 October 2008
DOI:10.1016/j.chroma.2008.08.064
A versatile, relatively selective, chemically and mechanically robust solid-phase microextraction (SPME) fiber based on methacrylic acid–trimethylolpropanetrimethacrylate (MAA/TRIM) co-polymers was developed in a simple way and directly coupled with gas chromatography. Thus, using a glass capillary as a “mold”, MAA/TRIM co-polymers were immobilized on a stainless steel wire base as a novel coating for SPME. The extraction performance of the MAA/TRIM-coated fiber was evaluated in detail using four triazines as model compounds, and several typical and important species of chemical compounds including opioids, xanthic alkaloids and phenoxyacetic acid herbicides were selected as additional examples to further illustrate the extraction mechanism and applicability of the fiber. The fiber showed high extraction efficiency for highly functionalized molecules (typically containing multiple amino, hydroxy, carbonyl and carboxy groups) via a hydrogen-bonding extraction mechanism. The maximum extraction ability and selectivity of the fiber could be obtained only in non-polar (aprotic) organic solvents, which are effective for the hydrogen-bonding interaction. The inherent chemical stability of MAA/TRIM co-polymers and the mechanical strength of the stainless steel wire as the fiber support made the MAA/TRIM-coated fiber highly durable in practical use.
Co-reporter:Zhi-jie Lin, Xiao-mei Chen, Zhi-min Cai, Munetaka Oyama, Xi Chen and Xiao-ru Wang
Crystal Growth & Design 2008 Volume 8(Issue 3) pp:863
Publication Date(Web):February 9, 2008
DOI:10.1021/cg070474a
In this study, the initial transformation of gold seed on indium tin oxide (ITO) surfaces was investigated. Gold nanoparticles (AuNPs) grew on ITO surfaces using a seed-mediated method. The reduction rate of gold(I) salt and the shapes of AuNPs were affected by the concentration of cetyltrimethylammonium bromide (CTAB). Gold nanorods (AuNRs) appeared when the CTAB concentration was above 75 mM, and the shapes agreed with the dispersing state of CTAB micelles in solution. CTAB was replaced by cetyltrimethylammonium chloride (CTAC) in the growth procedure. Only small gold nanospheres (AuNSs) appeared when the CTAC concentration was increased. This result agreed with the dispersing state of CTAC micelles in solution and implied that gold salts were not free in either CTAB or CTAC solution. A red shift of 14 nm in the UV–vis spectra of AuBr4− was found in the presence of CTAB, and furthermore, AuBr2− became stable. This indicated that the gold salt strongly bound to cetyltrimethylammonium ion (CTA+) and was capped with CTAB micelles. As a result, we postulated that the growth of symmetric gold seeds into asymmetric AuNPs were caused by the initial transformation of gold seeds into asymmetric ones with the assistance of the CTA+ micelles, which capped the gold salts.
Co-reporter:Jingbin Zeng, Binbin Yu, Wenfeng Chen, Zhijie Lin, Limei Zhang, Zequan Lin, Xi Chen, Xiaoru Wang
Journal of Chromatography A 2008 Volume 1188(Issue 1) pp:26-33
Publication Date(Web):18 April 2008
DOI:10.1016/j.chroma.2007.08.017
A ceramic/carbon composite was developed and applied as a novel coating for solid-phase microextraction (SPME). The ceramic/carbon coating exhibited several good properties for SPME, such as high extraction quantities and enhanced thermal and organic solvent stability. Under scanning electron microscopy (SEM), the tightly attached coating layer on stainless steel wire revealed excellent mechanical characteristics. Single fiber and fiber-to-fiber reproducibility were less than 6.9 and 9.5%, respectively. The effects of extraction and desorption parameters such as extraction time, stirring rate, ionic strength, and desorption temperature and desorption time on the extraction/desorption efficiency were investigated and optimized. Coupled to gas chromatography with a flame thermionic detector, the optimized SPME method was applied to the analysis of organophosphorus pesticides (OPPs) in aqueous samples. The calibration curves were linear from 0.05 to 200 ng mL−1 for fenchlorphos, pirimiphos-methyl, chlorpyrifos, ethion and from 0.2 to 200 ng mL−1 for quinalphos, and the limits of detection were between 5.2 and 34.6 ng L−1. The recovery of the OPPs spiked in real water samples at 5 ng mL−1 ranged from 86.2 to 103.4% and the relative standard deviations were less than 8.5%.
Co-reporter:Meihua Liu;Bin Qiu;Xia Jin;Lan Zhang;Guonan Chen
Journal of Separation Science 2008 Volume 31( Issue 4) pp:622-628
Publication Date(Web):
DOI:10.1002/jssc.200700497
Abstract
Three-phase hollow fiber-mediated liquid-phase microextraction followed by HPLC was used for the determination of three synthetic estrogens, namely diethylstilbestrol, dienestrol, and hexestrol, in wastewater. Extraction conditions including organic solvent, volume ratio between donor solution and acceptor phase, extraction time, stirring rate, donor phase and acceptor phase were optimized. The target compounds were extracted from a 10 mL aqueous sample at pH 1.5 (donor solution) through a 45 mm in length hollow polypropylene fiber that was immersed in 1-octanol in advance, and then the hollow fiber was filled with 10 μL 0.5 mol/L sodium hydroxide solution (acceptor phase). After a 40 min extraction, the acceptor phase was directly injected into an HPLC system for detection. Under the optimized extraction conditions, a large enrichment factor (more than 300-fold) was achieved for the three estrogens. The determination limit at an S/N of 3 ranged from 0.25 to 0.5 μg/L for the estrogens. The recovery ratio was more than 86% in the determination of these estrogens in wastewater.
Co-reporter:Xu-dong Wang Dr.;Zhao-xiong Xie Dr.;Xiao-ru Wang Dr.
Angewandte Chemie International Edition 2008 Volume 47( Issue 39) pp:7450-7453
Publication Date(Web):
DOI:10.1002/anie.200801733
Co-reporter:Zhijie Lin, Xiaomei Chen, Zhimin Cai, Peiwei Li, Xi Chen, Xiaoru Wang
Talanta 2008 Volume 75(Issue 2) pp:544-550
Publication Date(Web):15 April 2008
DOI:10.1016/j.talanta.2007.11.049
Amino acids with different chemical structures have different abilities in terms of increasing the intensity of chemiluminescence (CL) of tris(2,2′-bipyridine)ruthenium(II) [Ru(bpy)32+]. In a flow system, CL caused by the reaction between Ru(bpy)33+ and 15 amino acids was observed, but only tryptophan (Trp) and histidine (His) enhanced the intensity obviously, and so the CL of Trp and His and their molecular groups was studied. A calculation of the ionization potentials (IPs) of their N atom indicated that the CL intensities of these compounds depended on their IPs. In addition, the flow system was used for the determination of Trp and His, and the detection limits were 3 × 10−8 mol L−1 for His and 2.5 × 10−9 mol L−1 for Trp. The calibration curves for the two amino acids were 1.0 × 10−7 to 5.0 × 10−3 mol L−1 for His and 1.0 × 10−8 to 1.0 × 10−4 mol L−1 for Trp. The proposed approach was applied to the determination of His in Ganoderma.
Co-reporter:Xu-dong Wang Dr.;Zhao-xiong Xie Dr.;Xiao-ru Wang Dr.
Angewandte Chemie 2008 Volume 120( Issue 39) pp:7560-7563
Publication Date(Web):
DOI:10.1002/ange.200801733
Co-reporter:Dan Du, Jiawang Ding, Yuan Tao, Haibing Li, Xi Chen
Biosensors and Bioelectronics 2008 Volume 24(Issue 4) pp:863-868
Publication Date(Web):1 December 2008
DOI:10.1016/j.bios.2008.07.020
CdTe quantum dots (QDs)-based electrochemical sensor for recognition of neutravidin, as a model protein, using anodic stripping voltammetry at electrodeposited bismuth film is presented. This biosensor involves the immobilization of the captured QDs conjugates which was dissolved with 1 M HCl solution to release cadmium ions and metal components were quantified by anodic stripping voltammetry after a 3-min accumulation at −1.2 V on bismuth-film electrode (BiFE) of the biotin, served as recognition element, onto the gold surface in connection with a cysteamine self-assembled monolayer. The modification procedure was characterized by electrochemical impedance spectroscopy and atomic force microscopy. We exploit QDs as labels for amplifying signal output and monitoring the extent of competition process between CdTe-labeled neutravidin and the target neutravidin for the limited binding sites on biotin. As expected for the competitive mechanism, the recognition event thus yields distinct cadmium stripping voltammetric current peak, whose response decreases upon increasing the level of target neutravidin concentrations. Under optimal conditions, the voltammetric response is highly linear over the range of 0.5–100 ng L−1 neutravidin and the limit of detection is estimated to be 0.3 ng L−1 (5 nM). Unlike earlier two-step sandwich bioassays, the present protocol relies on a one-step competitive assay, which is more accurate and sensitive, showing great promise for rapid, simple and cost-effective analysis of protein.
Co-reporter:Dan Du, Shizhen Chen, Dandan Song, Haibing Li, Xi Chen
Biosensors and Bioelectronics 2008 Volume 24(Issue 3) pp:475-479
Publication Date(Web):15 November 2008
DOI:10.1016/j.bios.2008.05.005
In this paper, a novel acetylcholinesterase (AChE) biosensor was constructed by modifying glassy carbon electrode with CdTe quantum dots (QDs) and excellent conductive gold nanoparticles (GNPs) though chitosan microspheres to immobilize AChE. Since GNPs have shown widespread use particularly for constructing electrochemical biosensors through their high electron-transfer ability, the combined AChE exhibited high affinity to its substrate and thus a sensitive, fast and cheap method for determination of monocrotophos. The combination of CdTe QDs and GNPs promoted electron transfer and catalyzed the electro-oxidation of thiocholine, thus amplifying the detection sensitivity. This novel biosensing platform based on CdTe QDs–GNPs composite responded even more sensitively than that on CdTe QDs or GNPs alone because of the presence of synergistic effects in CdTe-GNPs film. The inhibition of monocrotophos was proportional to its concentration in two ranges, from 1 to 1000 ng mL−1 and from 2 to 15 μg mL−1, with a detection limit of 0.3 ng mL−1. The proposed biosensor showed good precision and reproducibility, acceptable stability and accuracy in garlic samples analysis.
Co-reporter:Xiao-mei Chen, Zhi-jie Lin, Zhi-min Cai, Xi Chen, Xiao-ru Wang
Talanta 2008 Volume 76(Issue 5) pp:1083-1087
Publication Date(Web):15 September 2008
DOI:10.1016/j.talanta.2008.05.007
A simple, novel electrochemiluminescence (ECL) method for the detection of dichlorvos pesticide (DDVP) with high sensitivity was discovered. Detection was carried out in a static ECL system, in which a glassy carbon electrode was selected as the working electrode. ECL parameters, including the concentrations of cetyrltrimethylammonium bromide and luminol, the solution pH, and the scan rate of the applied potential, were optimized. Under these optimal conditions, the linear response of ECL-emission versus DDVP concentration was valid in the range 5–8000 ng/L (r2 = 0.9982) with a relative standard deviation of 4.3% at 2000 ng/L (n = 10), yielding a detection limit (S/N = 3) of 0.42 ng/L. The ECL emission was caused by a radical reaction process, in which the dissolved oxygen in the luminol solution reacted with the DDVP and generated free radicals. The free radicals reacted with the luminol anion and yielded the luminol radical. The approach presented was successfully applied to the determination of DDVP residues in vegetable samples.
Co-reporter:Binbin Yu;JingBin Zeng;LiFen Gong;XiaoQing Yang;Limei Zhang
Science Bulletin 2008 Volume 53( Issue 1) pp:27-32
Publication Date(Web):2008 January
DOI:10.1007/s11434-007-0482-8
Photocatalytic degradation of dicofol was investigated on TiO2 nano particles (TiO2-NPs) under UV light irradiation. It was shown that dicofol could be completely degraded into inorganic chloride ion under the condition of 0.25 mg/mL TiO2-NPs, 2 h irradiation of 400 W high pressure mercury lamp with a wavelength of 365 nm and air at a rate of 100 mL/min. The effects of the experimental conditions, including the amount of TiO2-NPs, irradiation time and the intensity of light, were studied. The apparent photodegradation rate constant was 0.167/min under the optimal condition. The photocatalytic degradation mechanism of dicofol was also discussed.
Co-reporter:Dan Du, Jiawang Ding, Yuan Tao, Xi Chen
Sensors and Actuators B: Chemical 2008 Volume 134(Issue 2) pp:908-912
Publication Date(Web):25 September 2008
DOI:10.1016/j.snb.2008.06.040
One-step electrochemical deposition of gold nanoparticles (AuNPs) in chitosan hydrogel onto a planar gold electrode was used to create a favorable surface for the attachment of the enzyme acetylcholinesterase (AChE). AChE exhibited high affinity to its substrate of acetylthiocholine chloride (ATCl) from calculated Michealis–Menten constant (Kmapp) of 0.309 mM. Thiocholine, the product through AChE-catalyzed hydrolysis of ATCl, could be chemisorbed on the surface with an applied potential of −0.7 V and then desorbed in KOH solution, giving a measurable peak current. When enzymatic activity was inhibited by organophosphate pesticides, the amount of chemisorpted thiocholine on the interface was anticipated to decrease. As a result, a simple method for rapid determination of malathion was established based on the chemisorption/desorption process of thiocholine used as an indicator. Under the optimal conditions, the decrease in response was proportional to the concentration of malathion from 0.1 to 20 ng mL−1, with detection limit of 0.03 ng mL−1 (0.1 nM). The method based on one-step electrochemical deposition and chemisorption/desorption process of thiocholin has potential application in high-sensitive pesticide determinations.
Co-reporter:Maosheng Zhang, Jiarong Huang, Changlin Wei, Binbin Yu, Xiaoqing Yang, Xi Chen
Talanta 2008 Volume 74(Issue 4) pp:599-604
Publication Date(Web):15 January 2008
DOI:10.1016/j.talanta.2007.06.041
Co-reporter:Ying Tao, Zhi-Jie Lin, Xiao-Mei Chen, Xi Chen, Xiao-Ru Wang
Analytica Chimica Acta 2007 Volume 594(Issue 2) pp:169-174
Publication Date(Web):2 July 2007
DOI:10.1016/j.aca.2007.05.025
In this paper, a novel electrochemiluminescence (ECL) sensor was constructed to determine herring sperm (HS) double-stranded (ds) DNA. Tetramethoxysilane and dimethyldimethoxysilane were selected as co-precursors to form an organically modified silicate (ORMOSIL) film for the immobilization of multiwall carbon nanotubes (MWNTs) wrapped by poly(p-styrenesulfonate) (PSS), and then Tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) was successfully immobilized on a glassy carbon electrode via ion-association. PSS was employed to increase the conductivity of the ORMOSIL film and disperse the cut MWNTs, which were cut and shortened in a mixture of concentrated sulfuric and nitric acids, in the film. It was found that MWNTs could adsorb Ru(bpy)32+ and acted as conducting pathways to connect Ru(bpy)32+ sites to the electrode. MWNTs also played a key role as materials for the mechanical and thermal properties. The ECL performance of this modified electrode was evaluated in a flow injection analysis (FIA) system, and the detection limit (S/N = 3) for HS ds-DNA was 2.0 × 10−7 g mL−1 with a linear range from 1.34 × 10−6 to 6.67 × 10−4 g mL−1 (R2 = 0.9876). In addition, the ECL sensor presented excellent characteristics in terms of stability, reproducibility and application life.
Co-reporter:LingLing Xin;LaiLong Xiao;Li Zhao;XiaoRu Wang
Science Bulletin 2007 Volume 52( Issue 2) pp:188-193
Publication Date(Web):2007 January
DOI:10.1007/s11434-007-0012-8
An organically modified silicate (ORMOSIL) as a matrix for oxygen-sensitive sensor, in which dimethyldimethoxysilane was selected as an organic modifier in the precursor, is described. The sensing film with tris-(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) as an indicator developed in this paper was characterized by efficient quenching by oxygen. Blue light-emitting diodes (λmax = 475 nm) were employed as light excitation source. The linear range of the dissolved oxygen was from 0.5 to 16 μg/mL. The measured RSD was 2%, the response time (t95) was 60 s, and the determination limit was 0.2 μg/mL. A portable and inexpensive luminescence-based sensor was established and applied to the determination of dissolved oxygen in the surface water.
Co-reporter:Binbin Yu, Jingbin Zeng, Lifen Gong, Maosheng Zhang, Limei Zhang, Xi Chen
Talanta 2007 Volume 72(Issue 5) pp:1667-1674
Publication Date(Web):31 July 2007
DOI:10.1016/j.talanta.2007.03.013
The photocatalytic degradation of organochlorine pesticides including α-, β-, γ-, δ-hexachlorobenzene (BHC), dicofol and cypermethrin were carried out on a nano-TiO2 coated films under UV irradiation in the air. The photocatalytic conditions, including the amount of TiO2, irradiation time and the intensity of light were optimized. The pesticides were most effectively degraded under the condition of 2.24 mg/cm2 on TiO2 film and a 400 W UV irradiation of high-pressure mercury lamp with a wavelength of 365 nm. A typical organochlorine pesticide, 20 μg α-BHC, was dipped onto the TiO2 film surface and degraded completely within 20 min. In addition, the photocatalytic degradation pathways on the nano-TiO2 coated film were discussed.
Co-reporter:Bin Qiu;Hai-Ling Chen;Guo-Nan Chen
Luminescence 2007 Volume 22(Issue 3) pp:189-194
Publication Date(Web):29 JAN 2007
DOI:10.1002/bio.947
An ECL approach was developed for the determination of codeine or morphine based on tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)32+) immobilized in organically modified silicates (ORMOSILs). Tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMe-DiMOS) were selected as co-precursors for ORMOSILs, which were then immobilized on a surface of glassy carbon electrode (GCE) by a dip-coating process. Ru(bpy)32+ was immobilized in the ORMOSIL film via ion-association with poly(p-styrenesulphonate). The ORMOSIL-modified GCE presented good electrochemical and photochemical activities. In a flow system, the eluted codeine or morphine was oxidized on the modified GCE and reacted with immobilized Ru(bpy)32+ at a potential of +1.20 V (vs. Ag/AgCl). The modified electrode was used for the ECL determination of codeine or morphine and showed high sensitivity. The calibration curves were linear in the range 2 × 10−8–5 × 10−5 mol/L for codeine and 1 × 10−7–3 × 10−4 mol/L for morphine. The detection limit was 5 × 10−9 mol/L for codeine and 3 × 10−8 mol/L for morphine, at signal:noise ratio (S:N) = 3. Both codeine and morphine showed reproducibility with RSD values <2.5% at 1.0 × 10−6 mol/L. Furthermore, the modified electrode immobilized Ru(bpy)32+ was applied to the ECL determination of codeine or morphine in incitant samples. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:Yaqi Jiang, Lai-Long Xiao, Li Zhao, Xi Chen, Xiaoru Wang, Kwok-Yin Wong
Talanta 2006 Volume 70(Issue 1) pp:97-103
Publication Date(Web):15 August 2006
DOI:10.1016/j.talanta.2005.11.046
An automatic sensing system was developed using an optical BOD sensing film. The sensing film consists of an organically modified silicate (ORMOSIL) film embedded with an oxygen-sensitive Ru complex. A multi-microorganisms immobilization method was developed for the BOD sensing film preparation. Three different kinds of microorganisms, Bacillus licheniformis, Dietzia maris and Marinobacter marinus from seawater, were immobilized on a polyvinyl alcohol ORMOSILs. After preconditioning, the BOD biosensor could steadily perform well up to 10 months. The linear fluctuant coefficients (R2) in the range of 0.3–40 mg L−1 was 0.985 when a glucose/glutamate BOD standard was applied. The reproducible response for the BOD sensing film could be obtained within ±2.3% of the mean value in a series of 10 samples in 5.0 mg L−1 BOD standard GGA solution. The effects of temperature, pH and sodium chloride concentration on the two microbial films were studied as well. The BOD sensing system was tested and applied for the BOD determination of seawater.
Co-reporter:Ling Lin, Lai-Long Xiao, Sha Huang, Li Zhao, Jian-Shen Cui, Xiao-Hui Wang, Xi Chen
Biosensors and Bioelectronics 2006 Volume 21(Issue 9) pp:1703-1709
Publication Date(Web):15 March 2006
DOI:10.1016/j.bios.2005.08.007
A biochemical oxygen demand (BOD) sensor has been developed, which is based on an immobilized mixed culture of microorganisms combined with a dissolved oxygen (DO) optical fiber. The sensing film for BOD measurement consists of an organically-modified silicate (ORMOSIL) film embedded with tri(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) perchlorate and three kinds of seawater microorganisms immobilized on a polyvinyl alcohol sol–gel matrix. The BOD measurements were carried out in the kinetic mode inside a light-proof cell and with constant temperature. Measurements were taken for 3 min followed by 10 min recovery time in 10 mg/L glucose/glutamate (GGA) BOD standard solution, and the range of determination was from 0.2 to 40 mg/L GGA. The effects of temperature, pH and sodium chloride concentration on the BOD sensing films were studied. BOD values estimated by this optical BOD sensing film correlate well with those determined by the conventional BOD5 method for seawater samples.
Co-reporter:Li Zhao, Ying Tao, Xiaoqing Yang, Liyan Zhang, Munetaka Oyama, Xi Chen
Talanta 2006 Volume 70(Issue 1) pp:104-110
Publication Date(Web):15 August 2006
DOI:10.1016/j.talanta.2005.11.043
Electrogenerated chemiluminescences (ECLs) of alkaloids, such as berberine, trigonelline, allantoin and betaine, were studied in an aqueous alkaline buffer solution (pH 9.5), based on tris(2,2′-bipyridine)ruthenium(II) [Ru(bpy)32+] immobilized in organically modified silicates (ORMOSILs) film on a glassy carbon electrode (GCE). The immobilized Ru(bpy)32+ showed good electrochemical and photochemical activities. In a flow system, the eluted alkaloids were oxidized on the modified GCE, and reacted with immobilized Ru(bpy)32+ at the potential of +1.50 V (versus Ag/AgCl). The luminescence with λmax 610 nm was caused by a reaction of electrolytically formed Ru(bpy)33+ with an oxidized amine group to generate Ru(bpy)32+*. The determination limit was 5 × 10−6 mol L−1, 8 × 10−6 mol L−1, 2.0 × 10−5 mol L−1 and 5.0 × 10−5 mol L−1 for berberine, trigonelline, allantoin and betaine at S/N 3, respectively. In addition, the factors affecting the determination of the four alkaloids were also studied.
Co-reporter:Changqing Yi, Yin Tao, Bo Wang, Xi Chen
Analytica Chimica Acta 2005 Volume 541(1–2) pp:73-81
Publication Date(Web):13 June 2005
DOI:10.1016/j.aca.2004.09.003
Tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMe–DiMOS) were used as co-precursor to immobilize poly(p-styrenesulfonate) (PSS), then tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)32+) was successfully immobilized on a glass carbon electrode via ion-association. The immobilized Ru(bpy)32+ shows good electrochemical and photochemical activities. Electrochemical and electrochemiluminescence (ECL) characterizations of the organically modified silicates (ORMOSILs) modified film electrodes were made by means of cyclic voltammetry and chronocoulometry. The ORMOSIL films were investigated by atomic force microscopy, scanning electrochemical microscope, tunnelling electrochemical microscope, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and fluorescence spectroscopy. XPS in-depth profiles revealed a homogeneous distribution of Ru(bpy)32+ inside the silica thin layers. The modified electrode was used for the ECL determination of methamphetamine (METH) and showed high sensitivity. Detection limit was 2.0 × 10−7 mol l−1 for METH (S/N = 3) with a linear range from 5.0 × 10−7 to 1.0 × 10−3 mol l−1 (R = 0.986). The relative standard deviation (n = 6) was 1.1% for the determination of 1.0 × 10−5 mol l−1 METH. Furthermore, the Ru(bpy)32+ immobilized modified electrode was applied in the ECL determination of methamphetamine (METH) in scout cases.
Co-reporter:Zenghong Xie;Guonan Chen;Ying Tao;Li Zhao
Luminescence 2005 Volume 20(Issue 3) pp:109-116
Publication Date(Web):27 MAY 2005
DOI:10.1002/bio.828
Electrochemiluminescence (ECL) based on allantoin and tris(2,2′-bipyridine)ruthenium (II) [Ru(bpy)32+] was studied in aqueous alkaline buffer solution (pH 11.0). In a flowing system, the eluted allantoin was mixed with 1.0 mmol[sol ]L Ru(bpy)32+. When the solution passed through a thin layer flow electrolytic cell equipped with a glassy carbon disc electrode (22.1 mm2), both hydroxyl groups of allantoin and Ru(bpy)32+ were oxidized at the potential of +1.50 V (vs. Ag[sol ]AgCl). The luminescence with λmax 610 nm caused by the reaction of electrolytically formed Ru(bpy)32+ with alkoxide radical to generate the excited state of Ru(bpy)32+*. A possible ECL process of allantoin in Ru(bpy)32+ alkaline solution has been discussed. In addition, the factors affecting the ECL response of allantoin are also investigated. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:Xi Chen, Changqing Yi, Xiaoqing Yang, Xiaoru Wang
Journal of Chromatography B 2004 Volume 812(1–2) pp:149-163
Publication Date(Web):5 December 2004
DOI:10.1016/j.jchromb.2004.08.032
Herbal medicines were one of the major resources for healthcare in earlier stages, and some traditional herbal medicines have been in use for more than 2000 years. Currently, they are attracting more and more attention of the modern pharmaceutical industry, as scientists has become aware that herbs have almost infinite resources for medicine development. This review provides an overview of the analytical approaches applied in the researches concentrated on various aspects of the matrine-type alkaloids in Sophora flavescens root. Emphasis will be laid on the analytical processes of high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), as well as gas chromatography (GC) methods. The sample extraction, separation and detection have been summarized. In addition, the applications of chromatographic determinations are introduced for the main matrine-type alkaloids in S. flavescens root, such as matrine, sophoridine, sophocarpine, lehmannine, sophoramine, oxymartine, oxysophocarpine, cytosine and aloperine. The advantages and limitations of HPLC, CE and GC methods in the analytical applications of the alkaloids are also discussed.
Co-reporter:Geng-huang Wu, Yan-fang Wu, Xi-wei Liu, Ming-cong Rong, Xiao-mei Chen, Xi Chen
Analytica Chimica Acta (1 October 2012) Volume 745() pp:33-37
Publication Date(Web):1 October 2012
DOI:10.1016/j.aca.2012.07.034
In this study, an electrochemical ascorbic acid (AA) sensor was constructed based on a glassy carbon electrode modified with palladium nanoparticles supported on graphene oxide (PdNPs-GO). PdNPs with a mean diameter of 2.6 nm were homogeneously deposited on GO sheets by the redox reaction between PdCl42− and GO. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards the oxidation of AA in neutral media. Compared to a bare GC or a Pd electrode, the anodic peak potential of AA (0.006 V) at PdNPs-GO modified electrode was shifted negatively, and the large anodic peak potential separation (0.172 V) of AA and dopamine (DA), which could contribute to the synergistic effect of GO and PdNPs, was investigated. A further amperometric experiment proved that the proposed sensor was capable of sensitive and selective sensing of AA even in the presence of DA and uric acid. The modified electrode exhibited a rapid response to AA within 5 s and the amperometric signal showed a good linear correlation to AA concentration in a broad range from 20 μM to 2.28 mM with a correlation coefficient of R = 0.9991. Moreover, the proposed sensor was applied to the determination of AA in vitamin C tablet samples. The satisfactory results obtained indicated that the proposed sensor was promising for the development of novel electrochemical sensing for AA determination.Graphical abstractDownload full-size imageHighlights► PdNPs with a mean diameter of 2.6 nm were homogeneously deposited on GO. ► The proposed sensor exhibited a rapid amperometric response to AA within 5 s. ► Good selectivity, wide linear range, low detection limit for AA.
Co-reporter:Wei Xu, Feiming Li, Zhixiong Cai, Yiru Wang, Feng Luo and Xi Chen
Journal of Materials Chemistry A 2016 - vol. 4(Issue 41) pp:NaN9655-9655
Publication Date(Web):2016/09/26
DOI:10.1039/C6TC01075J
An organic–inorganic hybrid fluorescent perovskite, CH3NH3PbBr3, was synthesized by a grinding method, and applied for humidity sensing. Its strong fluorescence at 530 nm could be linearly quenched by a humidity increase from 7 to 98%. Coupled with a red-emitting reference dye, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, a colorimetric humidity sensor was produced using the perovskite. The sensor appeared to be sensitive to increased humidity by displaying a color change from green to red, or vice versa, with good reversibility. The proposed approach should provide a new strategy in the design of sensitive and applicable humidity sensors.
Co-reporter:Xiaomei Chen, Bingyuan Su, Genghuang Wu, Chaoyong James Yang, Zhixia Zhuang, Xiaoru Wang and Xi Chen
Journal of Materials Chemistry A 2012 - vol. 22(Issue 22) pp:NaN11289-11289
Publication Date(Web):2012/04/04
DOI:10.1039/C2JM31133J
This paper reports a nontoxic, rapid, one-pot and template-free synthesis of three-dimensional (3D) Pt nanoflowers (PtNFs) with high yield and good size monodispersity supported on graphene oxide (GO) nanosheets. The key synthesis strategy employed a low-cost, green solvent, ethanol as the reductant and an advanced, powerful 2D carbon material, GO nanosheets as the stabilizing material. The resulting PtNFs-GO nanosheets were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. It was found that the monodispersed, porous PtNFs supported on GO nanosheets were a uniform size of 30 nm and each was composed of numerous “clean” and small (4 nm) Pt nanoparticles, which revealed an unusually high activity for methanol oxidation reaction compared to commercial Pt black. Furthermore, based on a systematic study of the PtNFs growth conditions, a possible mechanism, and especially the importance of GO in the formation was proposed. Our study demonstrates that GO is a promising support material for developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.
Co-reporter:Wei Xu, Sisi Lu, Mengxi Xu, Yaqi Jiang, Yiru Wang and Xi Chen
Journal of Materials Chemistry A 2016 - vol. 4(Issue 2) pp:NaN298-298
Publication Date(Web):2015/11/23
DOI:10.1039/C5TB02071A
We developed novel functionalized semiconducting polymer dots (Pdots) for the simultaneous imaging of intracellular pH and oxygen. The Pdots comprised a semiconducting polymer of poly[9,9-dioctylfluorenyl-2,7-diyl] (PFO), amino terminated polystyrene, fluorescein isothiocyanate (FITC) as a pH sensitive dye, and Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) as an oxygen sensitive dye. In the sensing Pdots, PFO was used as a donor for Förster resonance energy transfer. The emission wavelengths of the PFO, FITC and PtTFPP matched the three color channel of the red, green and blue chip, which offered great advantage for dual sensing using conventional fluorescence microscopy. The nanosensor was taken up by cells via endocytosis, and exhibited high brightness, small particle size, triple color under a single excitation, a large two-photon absorbance cross-section and low-toxicity to cells. These salient features demonstrated the potential utility of the Pdots for dual pH and O2 imaging in cells.
Co-reporter:Chun-hua Ma, Ya-mei Shi, Liang-bi Chen, Yan-fang Wu and Xi Chen
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 12) pp:NaN4100-4100
Publication Date(Web):2012/10/03
DOI:10.1039/C2AY25878A
In this paper, an electrochemiluminescence (ECL) sensor is fabricated using a covalent bond immobilization approach. A glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs@GCE) was prepared using a wet chemical method which acts as a support for the ECL reagent. A monolayer of mercaptoacetic acid (MA) was then assembled onto the AuNPs@GCE surface. Finally, an ECL reagent, bis(2,2′-bipyridyl) (5-amno-1,10-phen) dichlororuthenium [Ru(bpy)2(phen-NH2)]22+, was attached onto the AuNPs@GCE by condensation of the amino group and carboxylic group of MA. Because [Ru(bpy)2(phen-NH2)]22+ is covalently immobilized on the electrode surface without any polymaterials and directly contacts to the electrolyte, in contrast to traditional ECL sensors fabricated using a polymer technique, mass transportation and electron transfer hindrance is negligible and ECL stability is increased obviously. The sensor is applied in cathodic ECL analysis and presents good performance in a linear range from 1.0 × 10−6 mol L−1 to 0.1 mol L−1 and a detection limit of 5 × 10−7 mol L−1 for potassium persulfate.
Co-reporter:
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 4) pp:NaN1004-1004
Publication Date(Web):2012/03/21
DOI:10.1039/C2AY25073J
Core-shell silica particles encapsulating two luminescent dyes with different emission wavelengths were prepared for ratiometric fluorescence sensing of pH. The composite core-shell structure particles contained a polyacrylonitrile (PAN) core surrounding a silica shell. Fluorescein isothiocyanate (FITC) encapsulated in the silica shell was taken as an indicator, Fluorescence emission from Ru(dpp)3(ClO4)2 immobilized in PAN core was used as a reference light. The ratiometric fluorescence signal from the core-shell silica particles were found with a linear range from pH 5.80 to 7.50 (R2 = 0.997). In addition, the morphology of the core-shell silica particles, the effects of temperature and co-existing substances were investigated. The core-shell silica particles were successfully applied to determination of pH value in water and urine samples.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 7) pp:
Publication Date(Web):
DOI:10.1039/C3AY26492K
A fluorescent probe, a rhodamine 6G derivative (R6GD), has been designed and synthesized for the determination of Fe(III). In HAc–NaAc buffer solution, R6GD exhibits highly selective and sensitive response toward Fe(III) based on the fluorescence quenching mechanism of R6GD due to the heavy atom effect of I3− formed in the reaction between KI and Fe(III). Under the optimal conditions, the concentration of Fe(III) showed good linear relationship with the fluorescence intensity change of R6GD. The linear response range of Fe(III) (R2 = 0.9923) was found from 0.1 to 6.0 μmol L−1 with the detection limit of 0.05 μmol L−1 of Fe(III). The recovery of the approach in the determination of Fe(III) in real water samples was 83.3–99.5%.
Co-reporter:Mingcong Rong, Xinhong Song, Tingting Zhao, Qiuhong Yao, Yiru Wang and Xi Chen
Journal of Materials Chemistry A 2015 - vol. 3(Issue 41) pp:NaN10924-10924
Publication Date(Web):2015/09/17
DOI:10.1039/C5TC02584B
Highly fluorescent phosphorus, oxygen-doped graphitic carbon nitride nanodots (P,O-g-C3N4 nanodots) were synthesized using chemical oxidation and hydrothermal etching of bulk P-g-C3N4 obtained via pyrolysis of phytic acid and melamine. The P,O-g-C3N4 nanodots emitted strong blue fluorescence with a high quantum yield of 90.2%, and displayed high resistance to photobleaching and high ionic strength. A sensitive and facile fluorescence sensing approach for Cu2+ was developed through fluorescence quenching based on the static fluorescence quenching and photoinduced electron transfer. Under optimal conditions, a rapid detection of Cu2+ could be completed in 5 min with a detection limit of 2 nM, and a linearity ranging from 0 to 1 μM. Using acetylthiocholine (ATCh) as the substrate, the fluorescence of the P,O-g-C3N4 nanodots–Cu2+ system could be sensitively turned on in the presence of acetylcholinesterase (AChE) through the reaction between Cu2+ and thiocholine, the hydrolysis product of ATCh by AChE. A linearity ranging from 0.01 to 3 mU mL−1 could be obtained with a detection limit of 0.01 mU mL−1. In addition, the proposed approach showed potential application for the detection of Cu2+ in natural water samples and AChE activity in human plasma.
Co-reporter:Guo Guangmei, Zhijie Lin and Xi Chen
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 1) pp:NaN55-55
Publication Date(Web):2010/12/08
DOI:10.1039/C0AY00620C
In order to use a water soluble organic electrochemiluminescence (ECL) reagent in an aqueous medium, a simple one-pot method was developed to synthesize 9,10-diphenylanthracene (9,10-DPA) doped polystyrene beads based on dispersion polymerization. The bead size was around 3 μm and they were well dispersed. Fluorescence experiments showed that the polystyrene beads were successfully doped in 9,10-DPA. The 9,10-DPA doped beads were then used in ECL studies, and they retained their ECL activity well. The results imply that polystyrene beads could be a suitable platform leading to the application of hydrophobic ECL reagents in aqueous media.
Co-reporter:Qingai Chen, Tingyao Zhou, Chunyan He, Yaqi Jiang and Xi Chen
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 7) pp:NaN1474-1474
Publication Date(Web):2011/06/21
DOI:10.1039/C1AY05023K
In this study, a rapid, convenient and in situ applicable Cu2+ sensor was constructed based on a luminescent layer immobilizing Ru(bpy)3Cl2 with a maximum wavelength of 600 nm, which was taken as the reference background light. The luminescence intensity of the layer was kept constant and isolated from the oxygen change in the solution due to the hybrid polyacrylonitrile–dimethylsulfoxide used in the immobilization of the Ru(bpy)3Cl2. The CdTe quantum dot (QD) luminescence, with a maximum wavelength of 520 nm, was quenched to different degrees depending on the Cu2+ concentration in the solution. Using a commercial camera, different colors could be captured in different Cu2+ concentrations. This color change was caused by the composite light with stable luminescence from the Ru(bpy)3Cl2 layer and the changeable fluorescence of the CdTe QDs. Sensor characteristics, including the co-existing ions, oxygen content, temperature effect, and sensor stability, were investigated.
Co-reporter:Lan Luan, Zhi-jie Lin, Genghuang Wu, Xiao-li Huang, Zhi-min Cai and Xi Chen
Chemical Communications 2011 - vol. 47(Issue 13) pp:NaN3965-3965
Publication Date(Web):2011/02/21
DOI:10.1039/C1CC00057H
In this paper, an electrochemiluminescence (ECL) encoding method was developed for the first time, based on a dual-dye system including Ru(bpy)32+ as an ECL emitter and fluorescein isothiocyanate (FITC) as a coding dye.
Co-reporter:Chun-Hua Lu, Juan Li, Xiu-Juan Qi, Xiao-Rong Song, Huang-Hao Yang, Xi Chen and Guo-Nan Chen
Journal of Materials Chemistry A 2011 - vol. 21(Issue 29) pp:NaN10919-10919
Publication Date(Web):2011/06/15
DOI:10.1039/C1JM11121C
In this article, we present a new method for the multiplex detection of nucleases by using graphene oxide (GO) as a platform. We introduce a Y-shaped DNA (Y-DNA) as the multiplex probe. The 5′ termini of the Y-DNA are labeled with carboxy fluorescein (FAM), 6-carboxy-X-rhodamine (ROX) and cyanine 5 (Cy5) and they include three nuclease cleavage sites corresponding to PvuII, EcoRV and HaeIII, respectively. Upon the addition of nucleases, the nucleases cleave the corresponding sites in Y-DNA. Then, short dsDNA fragments containing fluorophores were released from the Y-DNA. These dsDNA fragments were unstable and easy to unwind into two short ssDNAs. They were then adsorbed onto the GO surface. Because of the excellent electronic transference of GO, the fluorescence intensity of the fluorophores can be quenched efficiently. Therefore, by monitoring the fluorophores’ fluorescence change before and after the addition of the nucleases, it is easy to establish a platform of a Y-DNA/GO complex for the simultaneous multiplex detection of nucleases.
Co-reporter:Xu-dong Wang, Ting-yao Zhou, Xin-hong Song, Yaqi Jiang, Chaoyong James Yang and Xi Chen
Journal of Materials Chemistry A 2011 - vol. 21(Issue 44) pp:NaN17653-17653
Publication Date(Web):2011/10/06
DOI:10.1039/C1JM14162G
We fabricated a chameleon cloth which changed its vivid colours at different oxygen concentrations under ultraviolet excitation. Combined with a photographing technique, the chameleon cloth possesses the ability for real-time quantitative imaging of oxygen distribution, which could be used for quick location of dangerous oxygen-deficiencies and oxygen-free regions.
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