DNA-templated silver nanocluster as a label-free fluorescent probe for the highly sensitive and selective detection of mercury ions

摘要

We have constructed a label-free fluorescent probe using ssDNA-templated silver nanoclusters (Ag NCs), and its quantum yield (QY) was significantly higher (∼29%) compared to traditional water-soluble fluorescent metal nanoclusters. The proposed approach is simple, non-toxic, sensitive, and selective for the detection of mercuric ion (Hg~(2+)). The fluorescence intensity of ssDNA-Ag NCs was quenched significantly in the presence of Hg~(2+), which might be attributed to the strong interactions between them including the dynamic and static quenching mechanisms. Though Ag~+ induced a moderate interference to Hg~(2+), there was a negligible quenching in the presence of other metal cations. In addition, Hg~(2+) could be detected as low as 4.5 nM, within a good linear range from 0 to 150 nM (R~2 = 0.995). More importantly, this method has also been successfully applied to the detection of Hg~(2+) in the real water samples. Thus, the ssDNA-Ag NCs detection system is potentially suitable for Hg~(2+) sensing in environmental samples.