An acetylcholinesterase biosensor based on platinum nanoparticles-carboxylic graphene-nafion-modified electrode for detection of pesticides

A sensitive amperometric acetylcholinesterase (AChE) biosensor based on platinum nanoparticles (Pt NPs), carboxylic graphene (CGR), and nafion (NF)-modified glassy carbon electrode (GCE) has been developed. The Pt NPs-CGR-NF nanocomposites with excellent conductivity, catalysis, and biocompatibility offered an extremely hydrophilic surface for AChE adhesion. Chitosan (CS) was used as cross-linker to immobilize the AChE on Pt-CGR-NF-modified GCE. NF was used as a protective membrane of the AChE biosensors. The AChE biosensor showed favorable affinity to acetylthiocholine chloride (ATCl) and could catalyze the hydrolysis of ATCl with an apparent Michaelis-Menten constant value of 148 μM. Under optimum conditions, the biosensor detected methyl parathion in the linear range from 1.0 × 10−13 to 1 × 10−10 M and from 1.0 × 10−10 to 1 × 10−8 M with a detection limit of 5 × 10−14 M and detected carbofuran in the linear range from 1.0 × 10−12 to 1 × 10−10 M and from 1.0 × 10−10 to 1 × 10−8 M with a detection limit of 5 × 10−13 M. The biosensor exhibited good sensitivity, acceptable stability, and reproducibility, thus providing a promising tool for analysis of enzyme inhibitors.