Electrochemical biosensing of methyl parathion pesticide based on acetylcholinesterase immobilized onto Au–polypyrrole interlaced network-like nanocomposite

We developed a simple strategy for designing a highly sensitive electrochemical biosensor for organophosphate pesticides (OPs) based on acetylcholinesterase (AChE) immobilized onto Au nanoparticles–polypyrrole nanowires composite film modifid glassy carbon electrode (labeled as AChE–Au–PPy/GCE). Where, the generated Au nanoparticles (AuNPs) were homogenously distributed onto the interlaced PPy nanowires (PPy NWs) matrix, constructing a three-dimensional porous network. This network-like nanocomposite not only provided a biocompatible microenvironment to keep the bioactivity of AChE, but also exhibited a strong synergetic effect on improving the sensing properties of OPs. The combination of AuNPs and PPyNWs greatly catalyzed the oxidation of the enzymatically generated thiocholine product, thus increasing the detection sensitivity. On the basis of the inhibition of OPs on the enzymatic activity of AChE, the conditions for OPs detection were optimized by using methyl parathion as a model OP compound. The inhibition of methyl parathion was proportional to its concentration ranging from 0.005 to 0.12 and 0.5 to 4.5 μg mL−1. The detection limit was 2 ng mL−1. The developed biosensor exhibited good reproducibility and acceptable stability. This study provides a new promise tool for analysis of organophosphate pesticides.