An Acetylcholinesterase Biosensor Based on Graphene/Polyaniline Composite Film for Detection of Pesticides

This work reports a sensitive amperometric biosensor for organophosphate pesticides ( OPs) fabricated through modifying glassy carbon electrode with acetylcholinesterase ( AChE) immobilized on graphene/ polyaniline ( G/ PANI) composite film. The obtained G/ PANI composite films show large specific area, high conductivity, good biocompatibility, and fast redox properties and have perfect layered and encapsulated structures. The as- prepared biosensor shows high affinity to acetylthiocholine ( ATCl) with a Michaelis- Menten constant value of 0.20 mmol/ L. Furthermore, based on the inhibition of the enzymatic activity ( immobilized AChE) caused by the model compound of carbaryl ( one kind of pesticides), it is found that the inhibition activity of carbaryl is proportional to its concentration ranging from 38 to 194 ng center dot mL(-1). The developed biosensor shows a detection limit of 20 ng center dot mL-1 ( S/ N= 3) for OPs detection and exhibits good performance such as good reproducibility and acceptable stability, which makes it possible to provide a new and promising tool for the analysis of enzyme inhibitors.