Electrochemical aptasensing strategy for kanamycin detection based on target-triggered single-strand DNA adsorption on MoS2 nanosheets and enzymatic signal amplification

A selective and sensitive electrochemical aptasensing strategy was developed for kanamycin detection based on target-triggered single-strand DNA adsorption on MoS2 nanosheets and enzymatic signal amplification. Firstly, a Y-shape double-stranded DNA (dsDNA) was designed containing probe DNA, assist DNA (labeled with biotin at its 3'-terminal) and aptamer DNA. Then, in the presence of kanamycin, aptamer DNA can be released from the Y-shape dsDNA structure due to its interaction with kanamycin to form stable conjugate, which will destroy the Y-shape dsDNA structure and lead to the presence of two-fragment of single-stranded DNA (ssDNA) on the remained half-hybrid DNA structure (containing probe DNA and assist DNA). Based on the strong interaction between ssDNA and MoS2 nanosheets, the half-hybrid DNA structure can be captured on MoS2 nanosheets modified electrode surface, which triggers the subsequent immobilization of streptavidin-alkaline phosphatase (SA-ALP) compound. Under the catalysis of ALP, p-nitrophenol phosphate (PNPP) is hydrolyzed to produce p-nitrophenol (PNP). Based on the linear relationship between the electrochemical oxidation signal of PNP and kanamycin concentration, kanamycin can be detected with the detection limit of 0.029 nM (S/N = 3). The aptamer-MoS2 nanosheets based electrochemical biosensor shows good selectivity, reproducibility for kanamycin detection.