Studies on electrochemical organophosphate pesticide (OP) biosensor design based on ionic liquid functionalized graphene and a Co3O4 nanoparticle modified electrode

Abstract

In this study, a new type of organophosphate pesticide (OP) biosensor was successfully fabricated based on the immobilization of acetylcholinesterase (AChE) by cross-linking on a glassy carbon electrode (GCE) modified with ionic liquid functionalized graphene (IL-GR), Co₃O₄ nanoparticles and chitosan (CHI). The introduction of IL-GR and Co₃O₄ nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). For the oxidation of thiocholine, a hydrolysis product of acetylthiocholine, the peak current at the AChE/IL-GR/Co₃O₄/CHI/GCE electrode is larger than those at AChE/IL-GR/CHI/GCE and AChE/Co₃O₄/CHI/GCE electrodes. A linear relationship between the inhibition percentage (I%) and logarithm of the concentration of dimethoate was found in the range from 5.0 × 10⁻¹² to 1.0 × 10⁻⁷ M, with a detection limit of 1.0 × 10⁻¹³ M (S/N = 3). The proposed biosensor provided an efficient and promising platform for the immobilization of AChE and exhibited higher sensitivity and acceptable stability for the detection of organophosphate pesticides.