Primer Exchange Reaction Coupled with DNA-Templated Silver Nanoclusters for Label-Free and Sensitive Detection of MicroRNA.

MicroRNAs (MiRNAs) play pivotal roles in regulating gene expression, and serve as crucial biomarkers for diagnosis of a variety of disease. However, label-free and sensitive miRNA detection remains a huge challenge due to the low abundance. Herein, we developed an approach through integrating primer exchange reaction (PER) with DNA-templated silver nanoclusters (AgNCs) for label-free and sensitive miRNA detection. In this method, PER was used to amplify miRNA signals and produce single-strand DNA (ssDNA) sequences. The produced ssDNA sequences mediated DNA-templated AgNCs based signal generation by unfolding the designed hairpin probe (HP). The generated AgNCs signal was correlated with the dosage of target miRNA. Eventually, the established approach exhibited a low detection of limit of 47 fM with a great dynamic range of more than five orders of magnitude. In addition, the method was also utilized to detect the miRNA-31 expression in collected clinical samples from pancreatitis patients and demonstrated that miRNA-31 was upregulated in patients, showing a great promising of the method in clinical application.