Highly Sensitive Electrochemical Biosensing of Phoxim Pesticide Based on Ionic Liquid-Functionalized Graphene as Modifier

A facile, one-step synthesis of ionic liquid-functionalized graphene (IL-GR) nanocomposite using graphene oxide (GO) and amine-terminated ionic liquid (NH2-IL) was first presented through an epoxide ring-opening reaction, then acetylcholinesterase (AChE) was immobilized onto IL-GR nanocomposite film modified glassy carbon electrode to prepare a highly sensitive AChE biosensor. The morphologies and electrochemistry properties of the composite were investigated by using scanning electron microscopy, transmission electron microscopy and cyclic voltammetry, respectively. The nanocomposite 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 phoxim. The immobilized AChE showed favorable affinity to acetylthiocholine (ATCl) and could catalyze the hydrolysis of ATCl with a Kapp m value of 0.143 mM. The proposed biosensor exhibited a detection limit of 6.0 × 10–11 M (S/N = 3) towards phoxim. Besides, the biosensor is easy to prepare, have good stability, and will have potential application in organophosphate pesticides.