| Abstract: | The development of a nanographite (NG)‐based fluorescent biosensor for detecting microRNA (miRNA) is reported. Duplex‐specific nuclease (DSN)‐assisted signal amplification was key to its function. In the absence of a target, with the assistance of p‐stacking interactions, the NG adsorbed the double carboxyfluorescein (FAM)‐labelled probe (DFP) whose surface was perfectly complementary to miRNA, leading to quenching of FAM fluorescence. In the presence of a target, double‐stranded DNA/RNA hybrids were repelled by the NG and fluorescence was restored. Meanwhile, the considerable increase in signal strength and sensitivity suggests DSN‐mediated target recycling as an application. The detection limit of the proposed biosensor for miRNA was 10 pmol/L; there was a linear correlation when the miRNA concentration ranged from 50 pmol/L to 5 nmol/L. Additionally, the method could distinguish let‐7b from most let‐7 miRNA family members and was successfully used in a sample assay. This biosensor is a novel and highly sensitive tool for miRNA detection and has great potential for biochemical research, disease diagnosis, and therapy. |
