A highly sensitive electrochemical OP biosensor based on electrodeposition of Au–Pd bimetallic nanoparticles onto a functionalized graphene modified glassy carbon electrode

Abstract

A fast and stable organophosphate pesticide (OP) biosensor with enhanced sensitivity has been developed for the detection of OPs by using Au–Pd bimetallic nanoparticles and ionic liquid functionalized graphene–chitosan nanocomposites (Au–Pd/IL-GR–CHI). An electrodeposition method was first applied to form Au–Pd nanoparticles on the surface of IL-GR–CHI, which were characterized by scanning electron microscopy and electrochemical methods. The electron transfer resistance of the Au–Pd/IL-GR–CHI modified electrode was smaller than that of the Au/IL-GR–CHI (or Pd/IL-GR–CHI) modified electrode, indicating that the presence of Au–Pd/IL-GR–CHI hybrid nanocomposites on the electrode surface could improve the reactive sites, reduce the interfacial resistance, and make the electron transfer easier. The Au–Pd/IL-GR–CHI hybrid nanocomposites with excellent conductivity, catalytic activity and biocompatibility offered an extremely hydrophilic surface for AChE adhesion. Under optimal conditions, based on the inhibition of organophosphate pesticides (OPs) on the AChE activity, using phorate as a model compound, the biosensor detected phorate in the linear range from 5.0 × 10⁻¹⁶ to 2.5 × 10⁻¹³ M and from 4.9 × 10⁻¹³ to 9.5 × 10⁻⁶ M, with a detection limit of 2.5 × 10⁻¹⁶ M (S/N = 3). The developed biosensor exhibited many advantages such as high sensitivity, acceptable stability and low cost, thus providing a promising tool for the analysis of OPs.