Nano-interface driven electrochemical sensor for pesticides detection based on the acetylcholinesterase enzyme inhibition

Forensic Science Laboratories usually receive numerous cases of suicidal, accidental, and homicidal poisoning most often involving organophosphorus (OP) pesticides. The toxicity of the OP pesticides arises due to their ability to inhibit the activity of acetylcholinesterase (AChE), a cholinergic enzyme that is essential for the proper functioning of the central nervous system. Conventional techniques which are currently in use for pesticide detection are time-consuming, need upskilled technicians as well as suffer from low sensitivity. Therefore, the more rapid and sensitive electrochemical biosensors based on the principle of AChE enzyme inhibition have emerged out to be a simple and promising alternative to the conventional techniques. Since, most of the time, the poison isolated from biological material in poisoning cases is in nM quantities, an attempt has been made for the development of biosensor with enhanced sensitivity in the nM range using reduced graphene oxide (rGO) and zinc oxide nanoflowers (ZnONFs). The rGO and ZnONFs were synthesized chemically and deposited electrochemically on the Au electrode. AChE was immobilized onto this prepared nano-interface (ZnONFs/rGO/Au) through chitosan and glutaraldehyde cross-linking. The fabricated sensor was characterized step by step with cyclic voltammogram and electrochemical impedance spectroscopy. This advanced nanomaterials based techniques has been explored for detecting pesticides in visceral samples. The limit of detection (LOD) for the present sensor was 0.01 nM for OP pesticides.