Tetrahedral DNA cluster-based signal-amplified Impedimetric biosensor for ultrasensitive detection of Ochratoxin A

Ochratoxin A (OTA) is a highly toxic mycotoxin with nepHrotoxicity, hepatotoxicity, and carcinogenicity. It poses a long-term threat to the health of humans and animals. Although screen printed electrodes (SPE) with aptamer functionalization provide promising detection capabilities, their applications are limited by inherent weak electrochemical signals, prompting the need for signal amplification strategies. In this study, tetrahedral DNA clusters (TDCs) were prepared as aptamer probes for OTA, and an aptamer-based electrochemical sensing method for OTA was established for signal amplification. Multiple single-stranded DNA (ssDNA) were designed to self-assemble into tetrahedral DNA nanostructure (TDN) through base complementarity, with the OTA aptamer attached to one vertex. Additional ssDNA strands were further utilized to extend TDNs at the three remaining vertices, forming a DNA tetrahedral cluster. The method had a linear range of 1 pg/mL to 100 ng/mL (LOD = 1 pg/mL) for detecting OTA, with excellent specificity and satisfactory recovery rate in feed samples