A fluorescent aptasensor based on DNA-scaffolded silver-nanocluster for ochratoxin A detection.

The selective detection of ultratrace amounts of ochratoxin A (OTA) is extremely important for food safety since it is one of the most toxic and widespread mycotoxin. Here we develop a signal-on fluorescent biosensor for detection of OTA based on fluorescent DNA-scaffolded silver-nanocluster (AgNCs), structure-switching of anti-OTA aptamer (Ap) and magnetic beads (MBs), and demonstrate its feasibility in the application of detecting OTA in real samples of wheat. The method exhibits superior sensitivity with a detection limit as low as 2 pg/mL OTA with high specificity. To the best of our knowledge, this is the first attempt to detect OTA based on DNA-scaffolded AgNCs, which possesses relatively high fluorescence quantum yield and photostability with regard to traditional organic dyes and quantum dots. Moreover, combined with the merits of MBs and aptamer, the proposed sensor has many advantages such as fabrication easiness, operation convenience, low cost, and being fast and portable, which may represent a promising path toward routine OTA control.