Electrochemical biosensor based on PANI/AuNPs composites for highly specific rapid detection of chlorpyrifos residues in traditional Chinese medicines

Chlorpyrifos was an insecticide and acaricide that interrupted nerve conduction by reducing the activity of the enzyme acetylcholinesterase. It could enter the human body through a variety of channels and produce serious physiological effects. However, excessive use of chlorpyrifos in herbal production produced excessive pesticide residues and reduced the yield of high-quality herbs. Therefore, the development of effective and convenient chlorpyrifos residue detection technology was critical for pesticide residue monitoring as well as danger avoidance. Based on this, an electrochemical enzyme biosensor using acetylcholinesterase as the recognition element was constructed for highly sensitive and rapid detection of chlorpyrifos in traditional Chinese medicine. The electrode substrate modification material was a polyaniline/gold nanoparticles composite material prepared by polyaniline functional modification of gold nanoparticles with high conductivity and large specific surface area, which had excellent electrical conductivity and biocompatibility. Specifically, the polyaniline/gold nanoparticles offered an exceptional active site for acetylcholinesterase immobilization, greatly enhancing the electrical signals resulting from acetylcholinesterase-catalyzed iodination of acetylthiocholine and accelerating electron transfer. In contrast, acetylcholinesterase's better identification of the target analyte chlorpyrifos meant that the sensor was highly selective for organophosphorus pesticide residues. Under optimized conditions, the sensor showed good linearity in the range of 1.00 × 10^–3 ~ 1.00 × 10¹ ppm with a detection limit of 7.90 × 10^–5 ppm. During practical sample testing, the sensor exhibited remarkable stability, reproducibility, and sensitivity in detecting chlorpyrifos pesticide residues in Chinese herbal medicines. This offered a reliable tool for precise monitoring and propelled the progress of enzyme-based biosensors, both in fostering the cultivation and production of superior-quality herbal medicines, as well as in enabling rapid on-site pesticide residue detection.