Label-Free Analysis of H5N1 Virus Based on Three-Segment Branched DNA-Templated Fluorescent Silver Nanoclusters

Since H5N1 virus is a highly infectious pathogen that causes outbreaks of avian influenza, developing a sensitive and rapid diagnostic platform to sense it becomes significant. Here, a novel label-free fluorescence sensing platform based on DNA-templated silver nanoclusters (DNA-Ag NCs) is developed to detect the H5N1 gene sequence representing H5N1 virus. The three-segment-branched DNA structure with closed cytosine-rich loop is designed as an effective template to produce fluorescent Ag NCs, which is different with the previous design of cytosine-rich loop formed by hairpin-like single-stranded DNA or double-stranded DNA. The proposed fluorescence detection approach gives a wide linear range (500 pM-2 μM) and a low detection limit (500 pM) to sense H5N1 gene sequence. Furthermore, selective analysis of target DNA shows that our constructed analytical strategy has a high selectivity to H5N1 gene sequence. It is regarded as a promising method for highly sensitive and selective sensing of H5N1 virus.