DSN signal amplification strategy based nanochannels biosensor for the detection of miRNAs

MiRNA-21 is recognized as an important biological marker for the diagnosis, treatment, and prognosis of breast cancer. Here, we have created a nanochannel biosensor utilizing the duplex-specific nuclease (DSN) signal amplification strategy to achieve the detection of miRNAs. In this system, DNA as the capture probe was covalently immobilized on the surface of nanochannels, which hybridized with the target miRNA and forms RNA/DNA duplexes. DSN could cleave the probe DNA in RNA/DNA duplexes, recycling target miRNA, which may again hybridized with other DNA probes. After N cycles, most of the DNA probes had been cleaved, and the content of miRNA could be quantified by detecting changes in surface charge density. This biosensor can distinguish miR-21 from non-complementary miRNAs and one-base mismatched miRNAs, with reliable detection limits as low as 1 fM in PBS. In addition, we had successfully applied this method to analysis of total RNA samples in MCF-7 cells and HeLa cells, and the nanochannels had also shown excellent responsiveness and strong antiinterference ability. This new method is expected to contribute to miRNA detection in clinical diagnostics, providing a unique approach to detecting and distinguishing disease-associated molecules.