MXene-rGO nanocomposite based electrochemical immunosensor for detection of endosulfan - An organochlorine pesticide

Abstract

Endosulfan (Ed), a widely used organochlorine pesticide, is classified as a persistent organic pollutant (POP). Its long half-life, resistance to degradation, and bioaccumulation in the food chain contaminates soil, water, and air. Such widespread environmental damage triggers monitoring its levels for ensuring compliance with safety regulations and protecting public health. In the current work, Ed was chemically altered and coupled with a carrier protein to elicit an immunological response. The purified in-house generated antibodies against Ed (Ed-Ab) were characterized by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). MXene, a class of 2D inorganic compounds, is known to depict significant optoelectrical potential. Herein, we have synthesized a novel nanocomposite of MXene and reduced graphene oxide (rGO). For designing the MXene-rGO biosensor, Ed-Ab were combined with the nanocomposite post characterization by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). Using the differential pulse voltammetry (DPV), electrochemical parameters such as pH, temperature, scan rate and response time of the electrode were evaluated. The fabricated electro-immunosensor was employed for the detection of endosulfan wherein the limit of detection (LOD) for Ed was determined to be 0.497 ppt with a linear range of 0.1 ppt-1 ppm. The composed electrode's working efficacy and sensitivity against similar cross-reactive pesticides was also determined. The MXene-rGO based nanocomposite depicted potential for determination of Ed traces in environmental samples.

Keywords: Electrochemical; Endosulfan; Immunosensor; MXene; Reduced graphene oxide.