A carbon fiber modified with tin oxide/graphitic carbon nitride as an electrochemical indirect competitive immuno-sensor for ultrasensitive aflatoxin M detection.

The importance of developing multifunctional nanomaterials for sensing technologies is increasing with the arrival of nanotechnology. In this study, we describe the introduction of novel nanoprobe electro-active material into the architecture of an electrochemical immuno-sensor. Based on the electrochemical immuno-sensor, functionalized tin oxide/graphitic carbon nitride nanocomposite (fSnO/g-CN) was synthesized and then analyte specific anti-aflatoxin M monoclonal antibody (AFM-ab) combined to form an electro-active nanoprobe (fSnO/g-CN/AFM-ab). First, aflatoxin M (AFM) conjugated bovine serum albumin (BSA-AFM) was electro-oxidized on the surface of carbon fiber (CF) followed by the consequent addition of nanoprobe. The formation of nanocomposite was substantiated through various characterization techniques, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Dynamic light scattering (DLS). Immuno-sensor fabrication was characterized via Field emission scanning electron microscopy (FE-SEM), optical microscope images, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). This immuno-sensor demonstrated good reproducibility, selectivity, specificity and sensitivity for AFM (LOD of 0.03 ng mL). Following spiking, this immuno-sensor produced good recovery values in the range of 94-96 % against real sample, such as milk. The development of sophisticated sensing methods for a range of analytes can greatly benefit from the widespread application of this innovative immuno-sensing approach.