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 is described based on the fluorescence quenching ability of MoS2 nanosheet and exonuclease III (Exo III) assisted dual. signal amplification. In this sensor, the fluorescence probes (HP1 and HP2) cannot be degraded by Exo III due to the 3'-termini protrusion and thus are adsorbed on the surface of MoS2 nanosheets, which will result in the quenching of MoS2 nanosheets toward the probes and induce a low fluorescent signal. The presence of the target DNA leads to the desorption of probes on the surface of MoS2 nanosheets due to the hybridization toward probes, generating many fluorescent fragments by Exo III digestion and inducing dual. signal amplification. This method can improve the sensitivity and detection limit compared with single amplification method, and shows excellent selectivity in the discrimination of single base mismatched targets. On the basis of the significantly high sensitivity, the developed biosensor can be potentially extended to detect various DNA targets with excellent sequence selectivity.