Synthesis of highly dispersed zinc oxide nanoparticles on carboxylic graphene for development a sensitive acetylcholinesterase biosensor

Highly dispersed zinc oxide nanoparticles (ZnO NPs) were synthesized on carboxylic graphene (CGR). A novel acetylcholinesterase (AChE) biosensor based on ZnO NPs, CGR and Nafion (NF) hybrids modified glass carbon electrode (GCE) has been successfully developed. ZnO NPs-CGR was homogeneously dispersed in NF and dropped on the surface of GCE. ZnO NPs-CGR-NF possessed excellent conductivity, catalysis and biocompatibility which were attributed to the synergistic effects of ZnO NPs, CGR and NF. ZnO NPs-CGR-NF/GCE provided a hydrophilic surface for AChE adhesion. 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 126 μM, which was then oxidized to produce a detectable and fast response. Under optimum conditions, the biosensor detected chlorpyrifos and carbofuran ranging from 1.0 × 10−13 to 1 × 10−8 M and from 1.0 × 10−12 to 1 × 10−8 M. The detection limits for chlorpyrifos and carbofuran were 5 × 10−14 M and 5.2 × 10−13 M, respectively. The developed biosensor exhibited many advantages such as good sensitivity, stability, reproducibility and low cost, thus providing a promising tool for analysis of enzyme inhibitors. This study could provide a universal platform for meeting the demand of the effective immobilization enzyme on the electrode surface.