A carbon fiber modified with tin oxide/graphitic carbon nitride as an electrochemical indirect competitive immuno-sensor for ultrasensitive aflatoxin M1 detection

Abstract

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 (fSnO₂/g-C₃N₄) was synthesized and then analyte specific anti-aflatoxin M₁ monoclonal antibody (AFM₁-ab) combined to form an electro-active nanoprobe (fSnO₂/g-C₃N₄/AFM₁-ab). First, aflatoxin M₁ (AFM₁) conjugated bovine serum albumin (BSA-AFM₁) 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 AFM₁ (LOD of 0.03 ng mL^-1). 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.

Keywords: BSA-AFM(1); Carbon fiber; Competitive immuno-assay; Nanomaterials; Nanoprobe.