Template DNA degradation-based fluorescent turn-off silver nanoclusters for nucleic acids detection with exonuclease III-assisted cycle amplification

Abstract

Abstract DNA-templated silver nanoclusters (DNA/AgNCs) exhibited the outstanding optical characteristics for molecular diagnosis. Herein, we developed the degradation of template DNA- based fluorescent turn-off template ssDNA/AgNCs probe to construct the nucleic acids detection platform with exonuclease III (Exo III)-assisted cycle amplification. Our results demonstrated that the template DNA degradation of DNA/AgNCs dramatically decreased the fluorescent signal own to the morphological change. Inspired by this mechanism, target nucleic acids in our detection system could effectively hybridize with template DNA of ssDNA/AgNCs, and template DNA were cyclically degraded by Exo III-assisted cyclic degradation. The degradation of template ssDNA induced the changing of the morphology and the decreasing of fluorescent of AgNCs. Target DNA can be detected at low temperature (37 oC) without thermal cycles, showing a wide linear relationship from 0.4 to 200 nM. The limit of detection (LOD) was as low as 0.1 nM. The strategy offered a promising method to nucleic acids detection, which had excellent practicability in testing.