Microchip-based bioelectrocatalytic determination of organophosphorus compounds

Abstract

We have developed a new detection method of organophosphorus (OP) nerve agent using acetylcholine esterase (AchE) and choline oxidase (ChOx) bienzyme system. AchE is inhibited by OP pesticide. So OP can be detected by the inhibition mechanism. To fabricate the AchE/ChOx bienzyme modified biosensing system, poly-L-lysine (PLL) and aldehyde terminated paramagnetic microparticle (MP) were used for enzyme immobilization. By using PLL, glutaraldehyde and amine rich electrode surface, ChOx were immobilized on the single micropatterned electrode. AchE was immobilized on the MP surface via Schiff's base formation. The resulting enzyme modified MPs were moved and deposited on the signaling electrode using magnet under microfluidic channel. To achieve whole OP detection procedures on the single microchip, microfluidic channel was employed to the microelectrode. Based on the bioelectrocatalytic reaction between AchE/ChOx bienzyme system and ferrocenyl electron shuttle, we successfully practiced the OP (e.g. diazinon) biosensing with the developed microchip.