An ultra-sensitive PEC aptasensor based on BiOI/Cu2O@Au heterojunction nanomaterials for the detection of OTA

A simple, rapid, label-free, and ultrasensitive photoelectrochemical (PEC) aptasensor towards Ochratoxin A (OTA), as one of the most carcinogenic secondary metabolites generated by Aspergillus and Penicillium spp was successfully developed based on BiOI/Cu2O@Au heterojunction nanomaterials that exhibit high electron-hole pair separation efficiency. Combining aptamers with high affinity and satisfactory specificity, the prepared PEC aptasensor displayed excellent performance and a wide linear response to OTA ranging from 10 fg⋅mL−1 ––10 ng⋅mL−1 with the detection limit as low as 2.5 fg⋅mL−1 (S/N = 3). In the end, the mechanism of the high-performance PEC aptasensor for the detection of OTA was discussed, which was the synergistic effect of high separation efficiency for the electron-hole (e− - h+) of BiOI/Cu2O heterostructures and the local surface plasmon resonance (LSPR) of Au NPs. The proposed PEC aptasensor was effectively utilized to detect OTA in red wine and Astragalus membranaceus samples with satisfactory results, demonstrating the practicality of the self-built PEC aptasensor described in this study for OTA detection in spiked samples. This work provides a viable strategy to develop an ultra-sensitive PEC aptasensor for the detection of OTA in actual traditional Chinese medicine and food safety analysis.