Duplex-specific nuclease assisted magnetic nanoprobe for cyclic amplified RNA detection

The recent spreading of viral diseases has led to the outbreak of pandemic and caused severe threats to public health worldwide. Though various approaches have been developed to detect viruses, there have only been a few reports on detecting viral RNA by cyclic signal amplification techniques. In search of an easy, cost-effective alternate method of gold-standard polymerase chain reaction (PCR), here, we have developed a duplexspecific nuclease (DSN)-based signal amplification method for RNA detection designing specific ssDNA-based nanoprobes. In the presence of target RNA under optimized conditions, DSN cleaves specifically the ssDNA in the DNA-RNA heteroduplex of the sensor to release the fluorophore from its quenched state while leaving the RNA strand free to react with another available nanoprobe for cyclic amplification. In this process, a single target RNA can interact with large numbers of nanoprobes, releasing amplified fluorophores from the core of the nanoprobes and increasing the fluorescence. The low detection limit of 11.5 fM has been achieved for a shortchain target RNA, indicating its potential application for the rapid RNA detection.