Label-Free Impedance Sensing of Aflatoxin B₁ with Polyaniline Nanofibers/Au Nanoparticle Electrode Array

Area of Science:

• Electrochemistry
• Nanomaterials Science
• Food Safety Analytics

Background:

• Aflatoxin B1 (AFB1) is a highly hepatotoxic and hepatocarcinogenic mycotoxin produced by Aspergillus fungi, posing a significant risk as a food contaminant.
• Current detection methods for AFB1 often lack the sensitivity and speed required for effective monitoring in various food matrices like peanuts, corn, and grains.
• The need for sensitive, expedient, and low-level detection strategies for mycotoxins is critical for ensuring food safety and preventing associated health risks.

Purpose of the Study:

• To develop and characterize a novel electrochemical impedance sensor for the selective and sensitive detection of Aflatoxin B1.
• To utilize a composite material of polyaniline nanofibers (PANI) coated with gold (Au) nanoparticles on indium tin oxide (ITO) electrodes as the sensing platform.
• To evaluate the sensor's performance, including sensitivity, selectivity, detection limit, and applicability in real food samples.

Main Methods:

• Fabrication of an electrochemical sensor using gold nanoparticle-decorated polyaniline nanofibers (Au-PANI) on an indium tin oxide (ITO) disk electrode.
• Characterization of the Au-PANI nanocomposite using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS).
• Detection of AFB1 by monitoring changes in impedance magnitude (|Z|) using a standard iron probe, correlating impedance changes with AFB1 concentration.

Main Results:

• The Au-PANI composite electrode demonstrated a significant 14-fold decrease in impedance magnitude (|Z|_1Hz) compared to the bare electrode, indicating enhanced sensing capabilities.
• The sensor achieved a high sensitivity and stability for AFB1 detection, with a linear detection range from 0.1 to 100 ng/mL and a low detection limit of 0.05 ng/mL.
• The developed sensor exhibited excellent selectivity against Ochratoxin A (OTA) and was successfully applied to detect AFB1 in spiked corn samples, demonstrating practical applicability.

Conclusions:

• The developed Au-PANI nanocomposite-based electrochemical sensor offers a highly sensitive, selective, and stable platform for detecting Aflatoxin B1 at low levels.
• The sensor's ability to detect AFB1 in spiked food samples highlights its potential for practical application in food safety monitoring.
• This technology shows promise for the development of point-of-care (POC) diagnostic tools for rapid mycotoxin detection, contributing to improved public health and food security.