A fluorescent aptasensor for kanamycin detection in milk, seafood and water samples using DNA-AgNCs and exonuclease I-assisted recycling amplification strategy.

High kanamycin (KAN) residue in the human body can seriously threaten human health. Therefore, there is an urgent need to develop an accurate, sensitive and simple biosensor to monitor KAN in food. Herein, an aptasensor for KAN has been developed by employing the split aptamer, DNA-templated silver nanoclusters (DNA-AgNCs), and Exonuclease I (Exo I). The aptasensor is composed of a signal recognition and transduction system consisting of split aptamers Apt1, Apt2 and the complementary sequence cDNA of Apt1, and an Exo I-assisted target recovery signal amplification system. The fluorescence signal of the aptasensor can be amplified by 48.98 % by Exo I. And the aptasensor can achieve an ultra-low detection limit of 1.07 nM with a good linear range of 5 nM to 50 nM and 75 nM to 1 μM. Meanwhile, the aptasensor has the characteristics of simple preparation, and convenient use, which has obvious advantages to detect KAN.