Label-free fluorescence detection of circulating microRNAs based on duplex-specific nuclease-assisted target recycling coupled with rolling circle amplification.

A simpler, more rapid and selective biosensor has been developed for the sensitive detection of circulating miRNAs (c-miRNAs) based on duplex-specific nuclease (DSN)-assisted target recycling coupled with rolling circle amplification (RCA) using SYBR Gold Dye as a signal indicator. This biosensor exhibits a tremendously low detection limit of 0.3 fM of c-miRNAs and shows high selectivity for one-base mismatched c-miRNA. In addition, most importantly, the biosensor could accurately determine the amounts of target c-miRNA in total c-miRNAs isolated from human serums and human cancer cell lines, which confirms that the biosensor could be used to quantify c-miRNAs in complex biological samples and for the clinical early diagnosis of cancers based on c-miRNAs detection.