Sensitive detection of monocrotophos using a voltametric immunosensor with randomly layered graphene oxide (GO) on fabricated electrode

Monocrotophos—a highly toxic organophosphate pesticide—is widely utilized in agriculture for managing crop-harming insects by inhibiting their acetylcholinesterase (AChE) enzyme. However, its excessive usage has led to acute poisoning incidents in animals and humans. Its high-water solubility resulted in significant leaching into the water bodies, causing pollution in those reservoirs. For addressing this concern and effective monitoring such contaminations, necessitated the development of a robust detection system. In response, we designed an electrochemical immunosensor (biosensor) primarily based on antibodies which specifically detects the monocrotophos. The initial step involved generating the biorecognition element, the anti-monocrotophos antibodies. This was achieved through the conjugation of monocrotophos to a carrier protein, bovine serum albumin (BSA) followed by immunization. Characterization of the resulting conjugate was carried out using spectroscopic, chromatographic, and electrophoretic methods. The antibodies were further analyzed by immunosorbent assays (ELISA) and SDS-PAGE to evaluate their properties. Subsequently, the generated antibodies were conjugated with graphene oxide (GO), acting as an electrochemical mediator, utilizing the zero-length conjugation method. The antibody-GO conjugate was then layered onto a fluorine-doped tin oxide (FTO) electrode for the electrochemical detection of monocrotophos by employing differential pulse voltammetry (DPV). The fabricated biosensor demonstrated a limit of detection (LOD) of 0.49 parts per million (ppm) and exhibited stability of up-to 4 weeks when stored. This developed system proves to be ideal for monitoring monocrotophos in laboratory settings and the first system to utilize the antibodies to specifically detect monocrotophos, presenting a promising approach to tackle its hazardous impact on the environment.