Highly sensitive detection of organophosphorus insecticides using magnetic microbeads and genetically engineered acetylcholinesterase

This work presents a biosensor for organophosphorus pesticides based on immobilisation of a highly sensitive genetically engineered acetylcholinesterase (B394) by affinity interactions on metal chelate-functionalised magnetic microbeads. The developed sensor has been compared with those based on the widely used Electric eel cholinesterase and a classical entrapment procedure in a polyvinylalcohol-based matrix. The use of the B394 enzyme allowed lowering both IC50 and LOD by a factor of 100 when compared with Electric eel enzyme sensor. The oriented and site-specific immobilisation combined with the high specificity of the B349 mutant allows a more sensitive detection of insecticides, concentrations as low as 1.3 x 10(-11) M (IC10) being detected for both pesticides chlorpyriphos-oxon and chlorfenvinphos. (c) 2007 Elsevier B.V. All rights reserved.