Impedimetric Label-Free Immunosensor on Disposable Modified Screen-Printed Electrodes for Ochratoxin A

An impedimetric label-free immunosensor on disposable screen-printed carbon electrodes (SPCE) for quantitative determination of Ochratoxin A (OTA) has been developed. After modification of the SPCE surface with gold nanoparticles (AuNPs), the anti-OTA was immobilized on theworking electrode through a cysteamine layer. After each coating step, the modified surfaces werecharacterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Thecapacitance was chosen as the best parameter that describes the reproducible change in electricalproperties of the electrode surface at different OTA concentrations and it was used to investigatethe analytical parameters of the developed immunosensor. Under optimized conditions, the immunosensor showed a linear relationship between 0.3 and 20 ng/mL with a low detection limit of 0.25 ng/mL, making it suitable to control OTA content in many common food products. Lastly, theimmunosensor was used to measure OTA in red wine samples and the results were compared with those registered with a competitive ELISA kit. The immunosensor was sensitive to OTA lower than 2 µg/kg, which represents the lower acceptable limit of OTA established by European legislation for common food products