Bienzyme amperometric probes for choline and choline esters assembled withnonconducting electrosynthesized polymers

Different nonconducting polymers have been synthesized on the surface of a platinum (Pt) electrode to assemble fast-response and sensitive amperometri c biosensors for choline, butyrylcholine, and acetylcholine, based on choli ne oxidase (ChOx) and acetylcholinesterase (AchE) or butyrylcholinesterase (BuchE), co-immobilized by crosslinking with bovine serum albumin (BSA) and glutaraldehyde (GLT). Also the electropolymerization conditions as scan ra te and time were optimized for each monomer in order to obtain the best per mselectivity, the highest interferences rejection and stability. The proced ure of immobilization was proven to be fast and simple and resulted in a be tter longterm stability and in a higher loading of the enzyme than that obt ained by the co-electropolymerization. Studies on reproducibility, lifetime of the immobilized enzymes, pH, temperature, interferences, buffers, respo nse time, storage and operational time of the biosensors have been carried out. The optimized biosensors allowed rapid quantitative assay of cholinest erase inhibitor paraoxon, with a detection limit of 0.1 ppb and a response time of less than ten seconds.