▎ 摘　　要

A highly sensitive organophosphates (OPs) amperometric biosensor was developed by immobilizing acetylcholinesterase (AChE) through covalent bonding to 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6)-graphene-chitosan composite. Because of the higher specific surface area of graphene and high ionic conductivity of the BMIMPF6, BMIMPF6-graphene-chitsoan composite material not only provided a biocompatible microenvironment to keep the bioactivity of AChE, but also exhibited a strong synergetic effect on improving the sensing properties of OPs. The combination of graphene and BMIMPF6 catalyzed the electro-oxidation of thiocholine product, thus amplifying the detection sensitivity. Based on the inhibition of OPs on the enzymatic activity of AChE, the conditions for OPs detection were optimized by using malathion as a model. The inhibition of malathion was proportional to its concentration ranging from 0.1 nM to 1.0 nM and 1.0 nM to 10 nM, with a detection limit of 0.04 nM. Moreover, the developed biosensor exhibited good reproducibility and acceptable stability, and it has potential application in high-sensitive pesticide determinations.