Development of Ochratoxin Aptasensor Based on DNA Metal Nanoclusters

In this paper, a signal-off aptasensor was constructed based on the specificity of OTA and OTA aptamer (DNA2), it can detect the small molecule ochratoxin A (OTA). DNA1 chain with mercapto modified at 3′-end was firstly immobilized on gold electrode, which cross-fertilize with DNA 2 to form double strands. 30 thymine T modified at the end of DNA2 were used as templates to synthesize Cu NCs which is peroxidase mimics and can catalyze hydrogen peroxide. Presence of OTA, it specifically binds to DNA2, which made DNA2 dissociated, and so did Cu NCs. The more OTA in solution, the more the aptamers and Cu NCs dissociated from the gold electrode, the less copper nanoclusters remained on the electrode, and the smaller the current response value of the electrode measured by chronoamperometry. Thus, the quantitative determination of OTA can be achieved. This aptasensor provides a simple and fast technique for OTA detection in red wine samples.