摘要：
In this paper, a simple method for immobilization of acetylcholinesterase (AChE) on cysteamine assembled glassy carbon electrode coupled with gold nanoparticles (GNPs) was proposed and thus a sensitive, fast and stable amperometric biosensor for quantitative determination of monocrotophos was developed. The fabrication procedure was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and contact angles. The presence of GNPs not only led to an increased effective surface to provide a sufficient amount of sites for binding enzyme, but also promoted electron transfer reactions and catalyzed the electro-oxidation of thiocholine, thus amplifying the detection sensitivity. Due to the notable decrease in voltammetric signal of the immobilized AChE, a simple method for determination of monocrotophos was established. The inhibition of monocrotophos was proportional to its concentration in two ranges, from 0.5 to 10 ng mL(-1) and from 10 to 600 ng mL(-1), with a detection limit lower than 0.3 ng mL(-1). The constructed biosensor processing prominent characteristics and performance such as good precision and reproducibility, acceptable stability and accuracy, fast response and low detection limit has potential application in detection of toxic compounds.
摘要：
A series of novel 4-(4-(5-methyl-3-arylisoxazol-4-yl)thiazol-2-yl)piperidyl carboxamides and thiocarboxamides were synthesized as potential lead compounds of inhibitors targeting D1 protease in plants. These compounds were designed on the basis of a D1 protease inhibitor hit structure identified by homology modeling and virtual screening. The syntheses of these compounds were accomplished via a four-step procedure including the isoxazole ring formation, a-bromination of acetyl group, thiazole ring formation, and carboxamide/thiocarboxamide attachment. The in vivo herbicidal activity tests show that most compounds possess moderate to good herbicidal activities. The enzyme activity of one compound against the native spinach D1 protease exhibits a competitive inhibition. The results suggest that these compounds are indeed potential inhibitors for targeting D1 protease in plants.
摘要：
Multiwalled carbon nanotube (MWCNT) was developed as a new sorbent for solid-phase extraction (SPE) of organophosphate (OP) pesticides. A combination of SPE with square-wave voltammetric (SWV) analysis resulted in a fast, sensitive, and selective electrochemical method for determination of OP pesticide using methyl parathion (MP) as a representative. Because of the strong affinity of MWCNT for phosphoric group, nitroaromatic OP compounds can strongly bind to the MWCNT surface. The macroporosity and heterogeneity of MWCNT allow extracting a large amount of MP less than 5 min. The stripping response was highly linear over the MP range of 0.05-2.0 mu g/mL, with a detection limit of 0.005 mu g/mL. The determination of MP in garlic samples showed acceptable accuracy. The fast extraction ability of MWCNT makes it promising sorbent for various solid-phase extractions. (C) 2007 Elsevier B.V. All rights reserved.
摘要：
An amperometric pesticide biosensor has been devised by the composite assembly of silver nanoparticles with avidin and biotinylated acetylcholinesterase (AChE) on gold electrodes modified with a biotin-terminated self assembly monolayer (SAM). This composite assembly strategy takes use of the biospecific recognition avidin with the biotin from the SAM-terminals and biotinylated AChE, as well as the electrostatic interaction between silver nanoparticles with negatively charged citrate shell and avidin with encounter charge at pH 7.2. The construction process of the composite interface on gold was monitored by surface plasmon resonance (SPR), and its structure was characterized by attenuated total reflection Fourier-transform infrared spectra, atomic force microscopy and UV-vis spectra. The composite interface shows excellent electron transfer ability, as characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimum conditions a quantitative measurement of organophosphate pesticide dimethoate was achieved with the linear range of 0.05 mu M to10 mu M and the detection limit 0.01 mu M, taken as the concentration equivalent to a 10% decrease in signal. Silver nanoparticles conjugated biotin-avidin system represents a simple and functional approach to the integration of electrode sensing interface with improved biocompatibility and electron transfer ability, which may provide an analytical access to a large group of enzymes for bioelectrochemical application.
作者机构：
[Zhang, Aidong; Du, Dan; Tu, Haiyang; Ye, Xiuping; Zhang, Jiande; Zeng, Yan] Cent China Normal Univ, Coll Chem, Minist Educ, Key Lab Pesticide & Chem Biol, Wuhan 430079, Peoples R China.;[Liu, Deli] Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
通讯机构：
[Du, Dan] C;Cent China Normal Univ, Coll Chem, Minist Educ, Key Lab Pesticide & Chem Biol, Wuhan 430079, Peoples R China.
关键词：
zirconia nanoparticles;solid-phase extraction;square-wave voltammetry;methyl parathion;NERVE AGENTS;MULTILAYER FILMS
摘要：
A sensitive electrochemical stripping voltammetric method for analyzing organophosphate (OP) compounds was developed based on solid-phase extraction (SPE) at zirconia (ZrO2) nanoparticles modified electrode. ZrO2 nanoparticles were proved as a new sorbent for SPE of OP pesticides. Because of the strong affinity of ZrO2 for the phosphoric group, nitroaromatic OPs can strongly bind to the ZrO2 nanoparticle surface. The combination of SPE with square-wave voltammetry (SWV) provided a fast, sensitive, and selective electrochemical method for nitroaromatic OP compounds using methyl parathion (MP) as a model. The stripping response was highly linear over the MP range of 0.003-2.0 mu g/mL, with a detection limit of 0.001 mu g/mL. The fast extraction ability of ZrO2 nanoparticles makes it promising sorbent for various solid-phase extractions. (C) 2008 Elsevier B.V. All rights reserved.
摘要：
A simple method to immobilize acetylcholinesterase (AChE) on the controllable adsorption of multiwalled carbon nanotubes (MWCNTs) onto an alkanethiol self-assembled monolayer (C6H13SH SAM) modified Au electrode was proposed. The surface coverage of the MWCNTs was readily controlled by adjusting the immersion time for the adsorption of the MWCNTs. Atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to monitor these controllable fabrication processes. The MWCNTs adsorbed onto the SAM surface substantially restores the heterogeneous electron transfer between the bare Au electrode and the redox system in the solution phase that is almost totally blocked by the SAM of C6H13SH, and as a result, the prepared MWCNT-SAM-modified electrode possesses good electrode reactivity without a remarkable barrier to heterogeneous electron transfer. Due to the inherent conductive properties of MWCNTs, the immobilized AChE exhibited high affinity to its substrate and produced a detectable and fast response. Thus, a sensitive, efficient and stable amperometric sensor for quantitative determination of carbaryl was developed. The inhibition of carbaryl was proportional to its concentration ranging from 0.001 to 1 mu g mL(-1) and 2 to 15 mu g mL(-1), with a detection limit of 0.6 mu g mL(-1). The determination of carbaryl in garlic samples showed acceptable accuracy, which provided a new promising tool for analysis of enzyme inhibitors.
