A Portable Electrochemical Platform for Biorecognition-Free Detection of Ochratoxin A and Ascorbic Acid for Food Safety and Quality Monitoring

Abstract

Even a low concentration of mycotoxins in food and agricultural products can be extremely hazardous for the health of both humans and livestock. On the other hand, ascorbic acid, commonly referred to as vitamin C, can potentially reduce the levels of reactive oxygen species (ROS) generated from mycotoxin exposure. For the first time, this study reports the development of a biorecognition molecule-free electrochemical sensor that can detect both ochratoxin-A (OTA) mycotoxin and ascorbic acid (AA) simultaneously. Here, we present a paper-based electrode modified with tellurium oxide (TeO₂) sheets and nickel oxide (NiO) nanoparticles that enhance both the effective surface area and the electron transport rate through the transducer surface. NiO nanoparticles facilitate electrochemical oxidation, whereas TeO2 enhances current tunnelling across the electrode surface. This is the first report on the non-enzymatic electrochemical sensing application of tellurium oxide - nickel oxide conjugate. The sensor presents excellent selectivity and detection limits of 0.39 µg/mL for OTA and 9.17 µg/mL for AA in the linear range of 0.5 - 50 µg/mL and 5 - 500 µg/mL, respectively. Alongside, the sensor renders excellent storage stability for up to 30 days and surface reproducibility with a relative standard deviation of 2.20 %. High recovery rates in spiked food samples and no significant difference (P < 0.05) from real samples highlight its practical applicability. This study exhibits the advances of smartphone-integrated, paper-based, low-cost electrochemical sensors for rapid quality monitoring of food products.