A Dual-Mode Electrochemical Aptasensor for Ochratoxin A Detection in Red Wine Based on a Target-Induced Displacement Strategy

Ochratoxin A (OTA) is a mycotoxin of concern in wine and food safety, highlighting the need for reliable detection in complex food matrices. In this study, a dual-mode electrochemical aptasensor was developed for OTA determination in red wine based on a target-induced displacement strategy. OTA binding to its aptamer induces dissociation of the aptamer from complementary DNA (cDNA) pre-immobilized on the electrode surface, thereby altering the interfacial environment and enabling detection by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The sensor showed a semi-logarithmic calibration relationship over the experimentally tested OTA concentration range of 0.05–10 ng/mL. The estimated EIS limit of detection (LOD) was 0.018 ng/mL; however, this value was below the lowest tested concentration and was not experimentally validated. For DPV, 0.05 ng/mL represents the lower limit of the tested range rather than an established LOD. In spiked red wine, recoveries ranged from 94.6% to 103.9%, with relative standard deviations below 10%. The dual-mode strategy provides two readouts of the same target-induced interfacial change and offers potential for preliminary OTA screening in red wine with simplified sample pretreatment.