V-Type Nerve Agent Detection Using a Carbon Nanotube-Based Amperometric Enzyme Electrode

Abstract

An enzyme electrode for the detection of V-type nerve agents, VX (O-ethyl-S-2-diisopropylaminoethyl methylphosphonothioate) and R-VX (O-isobutyl-S-2-diethylaminoethyl methylphosphonothioate), is proposed. The principle of the new biosensor is based on the enzyme-catalyzed hydrolysis of the nerve agents and amperometric detection of the thiol-containing hydrolysis products at carbon nanotube-modified screen-printed electrodes. Demeton-S was used as a nerve agent mimic. 2-(Diethylamino)ethanethiol (DEAET) and 2-(dimethylamino)ethanethiol (DMAET), the thiol-containing hydrolysis product and hydrolysis product mimic of R-VX and VX, respectively, were monitored by exploiting the electrocatalytic activity of carbon nanotubes (CNT). As low as 2 microM DMAET and 0.8 microM DEAET were detected selectively at a low applied potential of 0.5 V vs Ag/AgCl at a CNT-modified mediator-free amperometric electrode. Further, the large surface area and the hydrophobicity of CNT was used to immobilize organophosphorus hydrolase mutant with improved catalytic activity for the hydrolysis of the P-S bond of phosphothiolester neurotoxins including VX and R-VX nerve gases to develop a novel, mediator-free, membrane-free biosensor for V-type nerve agents. The applicability of the biosensor was demonstrated for direct, rapid, and selective detection of V-type nerve agents' mimic demeton-S. The selectivity of the sensor against interferences and application to spiked lake water samples was demonstrated.

Electrochemical properties of surface-confined films of single-walled carbon nanotubes functionalised with cobalt(II)tetra-aminophthalocyanine: Electrocatalysis of sulfhydryl degradation products of V-type nerve agents

“…Also, using the BPPGE-SWCNT-CoTAPc (mix) , we determined the catalytic rate constants and diffusion coefficients of these analytes at constant concentration (at 10 −3 M in pH 9. agents and redox sites of surface-immobilised SWCNT-CoTAPc (mix) were determined using the established equation [59], [60] and [61]: (14) where I cat and I L are the currents of the BPPGE-SWCNT-CoTAPc (mix) here for these two thiol-degradation products, the few known reports [62] and [63] only dealt with their amperometric detection. Thus, this work is the first to provide detailed electrocatalytic parameters for DEAET and DMAET.…”

Electrocatalytic Oxidation of Diethylaminoethanethiol and Hydrazine at Single‐walled Carbon Nanotubes Modified with Prussian Blue Nanoparticles

“…Several methods of analysis such as chromatography, mass spectrometry, electrophoresis, flourimetry, and electrochemistry are common for the detection of these analytes [15][16][17] but with one limitation or the other such as very costly electrode preparation and complex procedures. For example, the polar non-volatile nature of thiol compounds renders them unsuitable for direct trace level analysis by GC.…”

Modified Cholinesterase Technology in the Construction of Biosensors for Organophosphorus Nerve Agents and Pesticides Detection

“…There were tests of some pesticides, such as paraoxon and parathion, and nerve agents, e.g. sarin or VX (Donarski et al, 1989; as cited in Wang et al, 1999;Joshi et al, 2006). So the organophosphorus compounds act for OPH as a substrate.…”