A Dual- signal Amplification Method for DNA Detection Based on Exonuclease III and Fluorescence Quenching Ability of MoS2 Nanosheet

A highly sensitive and selective DNA biosensor was described based on the fluorescence quenching ability of MoS2 nanosheet and exonuclease III (Exo III) assisted dual- signal amplification. In the absence of target DNA, two single oligonucleotides linked fluorophores (HP1 and HP2) resisted the digestion by Exo III due to the 3'-termini protrusion, resulting in low fluorescent signal by the adsorption and the quenching ability of MoS2 nanosheets toward single oligonucleotides and fluorophores. In the presence of target DNA, HP1 and HP2 were digested by Exo III because of the target DNA-induced two- step hybridization, and desorbed from the surface of MoS2 nanosheets, trigging dual- signal amplification. As a result, a large amount of fluorescent fragments and high fluorescent signal were generated. Under the optimal conditions, the proposed strategy could detect target DNA with a detection limit of 0.28 pM. In comparison with single amplification method, this method provided an improvement in the sensitivity and discrimination of single-base mismatch.