TiO2-decorated graphene nanohybrids for fabricating an amperometric acetylcholinesterase biosensor

Abstract

This work describes a highly sensitive and rapid amperometric biosensor for organophosphate compounds (OPs) based on immobilization of acetylcholinesterase (AChE) on a novel TiO₂-decorated graphene (TiO₂-G) nanohybrid, which was constructed by in situgrowth of TiO₂ nanoparticles (NPs) on the graphene sheet. The well-dispersed TiO₂ NPs eliminated the restacking of TiO₂-G nanohybrids. Due to the integrating of TiO₂-G nanohybrids, the as-prepared biosensor showed high affinity to acetylthiocholine (ATCl) with a Michaelis–Menten constant (K_m) value of 0.22 mM, and rapid inhibition time (3 min). Further, based on the inhibition of OPs on the enzymatic activity of the immobilized AChE, and using carbaryl as a model compound, the inhibition of carbaryl was proportional to its concentration ranging from 0.001 to 0.015 and 0.015 to 2 μg mL⁻¹ with a detection limit of 0.3 ng mL⁻¹ (S/N = 3). The developed biosensor exhibited a good performance for organophosphate pesticide detection, including good reproducibility and acceptable stability, which provided a new and promising tool for the analysis of enzyme inhibitors.