A G-quadruplex DNA-based, label-free and ultrasensitive strategy for microRNA detection

MicroRNAs (miRNAs) have been considered to be potent biomarkers for early disease diagnosis and for cancer therapy. The rapid and selective detection of miRNAs without reverse transcription and labelling is highly desired. Herein, we report a simple and label-free miRNA detection method that is based on the Duplex-Specific Nuclease (DSN)-Assisted simple target miRNA recycling procedure. The interaction of the G-quadruplex DNA structure with N-methyl mesoporphyrin IX (NMM) led to a label-free signal output. Under the optimised conditions, this method allowed for simple, rapid, and sequence-specific detection of miR-141 over a dynamic range from 1 fM to 100 nM with a linear range from 1 pM to 100 nM. Moreover, our method offered an excellent capacity to discriminate between miRNA family members with just one mismatched nucleotide. This simple and label-free strategy holds great potential in applications in biomedical research and in early clinical diagnostics.