DNA-silver nanocluster probe for norovirus RNA detection based on changes in secondary structure of nucleic acids.

DNA-templated silver nanoclusters (DNA-AgNCs) is a kind of fluorescent nanoclusters in-situ synthesized on DNA, thereby giving the DNA probe an inherent function of label-free signal output. Herein, the DNA-AgNCs with a GCC-loop-structure which has a quantum field of 51.6% was firstly proposed. It was proved that the addition of the double-stranded structure on the GCC-loop drastically enhanced the fluorescence intensity of the AgNCs. Through the further studies of the relationship between DNA secondary structure and AgNCs, a kind of DNA-AgNCs-probe was designed based on the change of the secondary structure which was induced by the target strand. By this, the fluorescence signal of probe was in "turn on" mode. The probe system could be directly used for the detection of Norovirus RNA, which had a linearity of 20 nM to 1.8 μM with a detection limit of 18 nM. Moreover, this detection platform was also selective to differentiate mismatched RNA. It was expected to be a universal method for different RNA detection by changing the recognition sequence of the probe.