Highly sensitive detection of organophosphate insecticides using biosensors based on genetically engineered acetylcholinesterase and poly(3,4- ethylenedioxythiophene)

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 100mv 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 1·10-10m. copyright © 2011 tomasz sikora et al.