Label-Free Impedance Sensing of Aflatoxin B-1 with Polyaniline Nanofibers/Au Nanoparticle Electrode Array

Abstract

Aflatoxin B-1 (AFB(1)) is produced by the Aspergillus flavus and Aspergillus parasiticus group of fungi which is most hepatotoxic and hepatocarcinogenic and occurs as a contaminant in a variety of foods. AFB(1) is mutagenic, teratogenic, and causes immunosuppression in animals and is mostly found in peanuts, corn, and food grains. Therefore, novel methodologies of sensitive and expedient strategy are often required to detect mycotoxins at the lowest level. Herein, we report an electrochemical impedance sensor that selectively detects AFB(1) at the lowest level by utilizing polyaniline nanofibers (PANI) coated with gold (Au) nanoparticles composite based indium tin oxide (ITO) disk electrodes. The Au-PANI nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, and electrochemical impedance spectroscopy (EIS). The composite electrode exhibited a 14-fold decrement in vertical bar Z vertical bar(1HZ) in comparison with the bare electrode. The Au-PANI acted as an effective sensing platform having high surface area, electrochemical conductivity, and biocompatibility which enabled greater loading deposits of capture antibodies. As a result, the presence of AFB(1) was screened with high sensitivity and stability by monitoring the changes in impedance magnitude (vertical bar Z vertical bar) in the presence of a standard iron probe which was target specific and proportional to logarithmic AFB(1) concentrations (C-AFB1). The sensor exhibits a linear range 0.1 to 100 ng/mL with a detection limit (36) of 0.05 ng/mL and possesses good reproducibility and high selectivity against another fungal mycotoxin, Ochratoxin A (OTA). With regard to the practicability, the proposed sensor was successfully applied to spiked corn samples and proved excellent potential for AFB(1) detection and development of point-of-care (POC) disease sensing applications.