摘要
Thioflavin T as split G-quadruplex fluorescent dye was researched. • A novel sensing method based on CoOOH nanoflakes and HCR was proposed. • Label-free and sensitive detection of miRNA-21 was successfully realized. To date, various fluorescent probes for G-quadruplex have been reported. However, the development of fluorescent dyes for split G-quadruplex formed on double-stranded DNA structure still remained largely unexplored. Herein, we have demonstrated that thioflavin T (ThT) was able to intercalate into split G-quadruplex sequence and the formed split G-quadruplex-ThT structure exhibited remarkable fluorescence enhancement. By integrating cobalt oxyhydroxide (CoOOH) nanoflakes and hybridization chain reaction (HCR), a sensitive and label-free biosensing strategy for miRNA detection was proposed. In our design, miRNA-21 was chosen as the model target and it was capable of triggering HCR with two split G-quadruplex sequence-contained hairpin probes, resulting in the generation of long chain-like HCR product. Unlike hairpin probes, the HCR product cannot be adsorbed onto CoOOH nanoflakes because of lower affinity. Consequently, in the presence of ThT, numerous split G-quadruplex-ThT structures on HCR product were formed and the target miRNA was converted into amplified and activatable fluorescence signal. Experimental results demonstrated that this novel sensing strategy can be applied for sensitive and selective detection of miRNA. Moreover, the analysis of miRNA in complex biological media was successfully realized, offering a robust, label-free and cost-effective platform for miRNA-related disease diagnosis and biomedical research. A novel fluorescence biosensing strategy based on cobalt oxyhydroxide (CoOOH) nanoflakes and hybridization chain reaction (HCR) was developed for sensitive and label-free detection of miRNA-21. Download: Download high-res image (161KB) Download: Download full-size image
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