Acetylcholinesterase biosensor based on electrochemically inducing 3D graphene oxide network/multi-walled carbon nanotube composites for detection of pesticides

Abstract

A sensitive electrochemical biosensor for determining organophosphates (OPs) and carbamate pesticides has been achieved by immobilizing acetylcholinesterase (AChE) on electrochemically inducing 3D graphene oxide network/multi-walled carbon nanotube composites (e-GON–MWCNTs). The nanocomposites of e-GON–MWCNTs can provide a favorable environment for the immobilized AChE and improve the electron transfer speed between the analyte and electrode surface. The fabricated AChE biosensors show a favorable affinity to acetylthiocholine chloride (ATCl) with a Michaelis–Menten constant of 0.43 mmol L⁻¹. In the optimal conditions, the biosensor exhibits a linear range of 0.03–0.81 ng mL⁻¹ for detecting carbofuran, and two linear ranges of 0.05–1 ng mL⁻¹ and 1–104 ng mL⁻¹ for detecting paraoxon. Furthermore, the detection limits for carbofuran and paraoxon can reach 0.015 and 0.025 ng mL⁻¹, respectively. The AChE biosensor exhibits good reproducibility and high stability, which demonstrates good efficiency in real sample analysis.