A novel method for detection of ochratoxin A in foods—Co-MOFs based dual signal ratiometric electrochemical aptamer sensor coupled with DNA walker

Ochratoxin A (OTA) is a naturally occurring mycotoxin that poses serious threats, such as kidney damage, to human health. Therefore, we developed a DNA walker-based dual-signal electrochemical ratiometric platform for OTA detection, which could overlook the variations in environmental and instrumental factors and DNA load densities. Cobalt metal–organic frameworks (Co-MOFs) and toluidine blue were used as the electrochemical signal tag and internal reference probe, respectively. In the presence of OTA, this developed machine resulted in the DNA labelled-Co-MOFs far away from the electrode. Thus, Co-MOFs signal at −1.18 V decreased, while toluidine blue at −0.28 V increased. This proposed strategy has displayed superior sensitivity (limit of detection = 0.31 fg/mL, linear range = 1–50 ng/mL) and high reproducibility. The sensor was also applied for determining OTA content in red wine samples and the results were comparable to those of commercial enzyme-linked immunoassay kits with satisfactory results.