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Chinese Journal of Chemistry 10/2009; 27(10):2043 - 2048. · 0.75 Impact Factor
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ABSTRACT: In this paper, an acetylcholinesterase (AChE)/dendrimers polyamidoamine (PAMAM)-Au/Carbon nanotubes (CNTs) multilayer modified electrode based on LbL self-assembled technique was employed in the detection of carbofuran in samples. The configuration of the nanostructure on the electrode provided a favorable environment to the immobilization of AChE. The modified films also improved the electrocatalytic characteristics and electron transfer speed between the films and the surface of electrode. The PAMAM-Au nanoparticles were characterized by SEM and UV-VIS methods. A set of experimental conditions were also optimized for the detection of the pesticides. A linear response over carbofuran concentration in the range of 4.8x10(-9)M to 0.9x10(-7)M was exhibited with a detection limit of 4.0x10(-9)M. The biosensor showed high sensitivity, good stability and reproducibility with promising application.
Bioelectrochemistry (Amsterdam, Netherlands) 09/2009; 77(2):139-44. · 2.65 Impact Factor
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ABSTRACT: In this study, a highly sensitive amperometric biosensor based on photoelectro-synergistic catalysis for detecting organophosphorus pesticides (OPs) in flow-injection analysis (FIA) system has been developed. The acetylcholinesterase enzyme (AChE) was immobilized by adsorption into the nanostructured PbO2/TiO2/Ti, which also acted as the working electrode. This strategy was found to catalyze the oxidative reaction of thiocholine effectively, make the AChE/PbO2/TiO2/Ti biosensor detect the substrate at 0.30 V (vs. SCE), hundreds milli-volts lower than others reported. PbO2/TiO2/Ti and TiO2/Ti electrodes were prepared and investigated with atomic force microscope (AFM). Factors influencing the performance were optimized. The resulting flow system offered a fast, sensitive, and stable response. A value of 1.34 mM for the apparent Michaelis-Menten constant (K(M)(app)) was obtained. A wide linear inhibition response for trichlorfon was observed in the range of 0.01-20 microM with the detection limit of 0.1 nM. The results using this biosensor agreed very well with chromatographic method and we also examined the real samples successfully in this work.
Analytica chimica acta 07/2009; 643(1-2):13-8. · 4.31 Impact Factor
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ABSTRACT: In this paper, Au-TiO2/Chit modified electrode was prepared with Au-TiO2 nanocomposite (Au-TiO2) and Chitosan (Chit) as a conjunct. The Au-TiO2 nanocomposite and the films were characterized by electrochemical and spectroscopy methods. A set of experimental conditions was also optimized for the film's fabrication. The electrochemical and electrocatalytic behaviors of Au-TiO2/Chit modified electrode to trace organophosphates (OPs) insecticides such as parathion were discussed in this work. By differential pulse voltammetry (DPV) measurement, the current responses of Au-TiO2/Chit modified electrode were linear with parathion concentration ranging from 1.0 ng/ml to 7.0 x 10(3)ng/ml with the detection limit of 0.5 ng/ml. In order to evaluate the performance of the detection system, we also examined the real samples successfully in this work. It exhibited a sensitive, rapid and easy-to-use method for the fast determination of trace OPs insecticides.
Talanta 08/2008; 76(4):758-62. · 3.79 Impact Factor
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ABSTRACT: In this paper, layer-by-layer {Hb/SiO2}n films assembled by alternate adsorption of positively charged hemoglobin (Hb) and vapor-surface sol-gel deposition of silica at 50 degrees C onto a glassy carbon electrode were reported. The result films were characterized with cyclic voltametery, electrochemical impedance spectroscopy, UV-vis spectroscopy, and SEM, and the direct electrochemical and electrocatalytic properties of Hb in these layer-by-layer films were investigated. A pair of well-defined quasi-reversible cyclic voltammetric peaks were observed, and the formal potential of the heme FeIII/FeII redox couple was found to be -0.330 V(vs SCE). The electron-transfer behavior of Hb in {Hb/SiO2}n films was dependent on the vapor temperature, the number of layers, and the pH of the Hb solution, based on which a set of optimized conditions for film fabrication was inferred. The hemoglobin in{Hb/SiO2}n films displayed good electrocatalytic activity to the reduction of hydrogen peroxide, and H2O2 had linear current response from 1.0 x 10(-6) to 2.0 x 10(-4) M with a detection limit of 5.0 x 10(-7) M (S/N = 3). The apparent heterogeneous electron-transfer rate constant (ks) was 1.02 +/- 0.03 s(-1), and the apparent Michaeli-Menten constant (Kmapp) was 0.155 mM, indicating a potential application in the third-generation biosensor.
Analytical Chemistry 06/2007; 79(10):3581-8. · 5.86 Impact Factor
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ABSTRACT: The {SBA/PSS}n/PDDA films modified electrode was prepared by layer-by-layer (LBL) assembly with mesoporous SiO2 (SBA), poly(sodium 4-styrene-sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) in this paper. SBA is a large pore-size mesoporous material with highly ordered hexagonally arranged mesochannels and high thermal stability etc. The electrochemical characteristics of the {SBA/PSS}n/PDDA films have been studied by electrochemical impedance spectroscopy in 0.1 M KCl solution containing 5.0 mM Fe(CN)63−/Fe(CN)64− at the formal potential of 0.230 V. The ultratrace nitroaromatic compounds (NACs) such as TNT, TNB, DNT and DNB were determined by differential pulse voltammetry (DPV) measurement. The sensitivities for NACs determination with {SBA/PSS}n/PDDA modified electrode were dependent on the number of layers, pH and ionic strength of electrolyte, based on which a set of optimized conditions for film fabrication was inferred. The current responses were linear with NACs ranging from 10−9 to 10−7 mol/l. The results showed that the {SBA/PSS}n/PDDA modified electrode established a new way for fast, simple and sensitive analysis of NACs.
Sensors and Actuators B: Chemical.
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ABSTRACT: In this paper, layer-by-layer {MSU/PDDA}n films assembled by alternate adsorption of mesoporous SiO2 (MSU) and Poly (diallyldimethylammonium chloride) (PDDA) onto a glassy carbon electrode were reported. MSU that we used in this work was synthesized by the precursor of zeolite Y and ionic liquid of 1-hexadecane-3-methylimidazolium bromide (CMIMB), which was used as a template in basic medium. It exhibited larger pore diameter, pore volume and surface area. The electrochemical characteristics of the {MSU/PDDA}n films have been studied by electrochemical impedance spectroscopy in 0.1 M KCl solution containing 5.0 mM . By differential pulse voltammetry (DPV) measurement, the ultratrace nitroaromatic compounds (NACs) such as TNT, TNB, DNT and DNB can be detected with nM level. The sensitivity for NACs determination in {MSU/PDDA}n films was dependent on the number of layers, pH and ionic strength of electrolyte, based on which a set of optimized conditions for film fabrication was inferred. The current responses were linear with NACs ranging from 10−9 mol/L to 10−7 mol/L with low detection limits. It is a sensitive, rapid and easy-to-use method for the fast determination of NACs.
Electrochemistry Communications 9(7):1719-1724. · 4.86 Impact Factor
