Highly Sensitive Detection of Organophosphate Insecticides Using Biosensors Based on Genetically Engineered Acetylcholinesterase and Poly(3,4-Ethylenedioxythiophene)

Tomasz Sikora,Georges Istamboulie,Estibalitz Ochoteco,Thierry Noguer,Elena Jubete,Jean-Louis Marty

doi:10.1155/2011/102827

Tomasz Sikora, Georges Istamboulie + Show 4 more

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https://doi.org/10.1155/2011/102827

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Abstract

A poly(3,4-ethylenedioxythiophene) (PEDOT) conducting ink is presented as a new electroactive material to be incorporated in acetylcholinesterase-(AChE-) based screen printed biosensors, acting not only as a conducting template but also as an electrochemical mediator for thiocholine oxidation. Two different strategies have been studied for the chemical synthesis of PEDOT: (a) a classical oxidative polymerisation and (b) a more innovative enzymatic polymerisation, giving a water-soluble PEDOT. The use of this water-soluble conducting polymer as mediator in screen-printed biosensors enables its deposition by printing like the rest of the layers. Highly sensitive acetylcholinesterase-(AChE-) based screen-printed biosensors have been constructed using both classical and enzymatic PEDOT, in combination with genetically modified AChE. These electrodes allow the measurement of thiocholine oxidation at potentials of 100 mV versus Ag/AgCl reference electrode through the mediation of PEDOT. Inhibition of thiocholine production in presence of CPO allow for detection of this pesticide in concentrations as low as 1·10−10 M.

Highlights

Biosensors are increasingly becoming powerful tools in clinical diagnostics, drug detection, and food and environmental monitoring
The ability of PEDOT modified screen-printed electrodes to detect thiocholine was studied by cyclic voltametry, by scanning the potential between −500 to 500 mV versus Ag/AgCl pseudo reference electrode
The sensors modified by cobalt-phtalocyanine-modified carbon paste (CoPC) presented an oxidation peak starting at −200 mV versus Ag/AgCl, characteristic of the mediated detection of thiocholine [34], while PEDOT modified electrodes, both classically and enzymatically synthesised showed an oxidation peak starting at −100 mV versus Ag/AgCl

Summary

Introduction

Biosensors are increasingly becoming powerful tools in clinical diagnostics, drug detection, and food and environmental monitoring. Electrochemical oxidation of thiocholine has been achieved at lower potentials using a graphite sensors modified using an appropriate redox mediator like phtalocyanine salts [6,7,8,9,10] or 7,7,8,8-tetracyanoquinodimethane (TCNQ) [11,12,13,14,15] can be used as chemical mediator. These two mediators incorporated in the graphite paste allow the electrochemical oxidation of thiocholine at 100 mV versus Ag/AgCl reference electrode

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