Strand displacement dual amplification miRNAs strategy with FRET between NaYF4:Yb,Tm/Er upconversion nanoparticles and Ti3C2 nanosheets

Due to the low abundance of miRNAs and the coordinated regulation of multiple miRNAs toward some biological processes, a method that can sensitively and simultaneously detect multiple miRNAs is needed. Here, a strand displacement dual amplification (SDDA) strategy was developed for multiple miRNAs analyses using a unique single strand-double strand-single strand DNA (sdsDNA), which generated by the target recognition probe hybridizing with the site region probe. During the process of SDDA, miRNA hybridized to the target recognition domain of sdsDNA, thereby releasing the site, which triggered the first strand displacement reaction. This strand displacement event resulted in the release of the other site, triggering the second strand displacement reaction. Both two strand displacement reactions in each assembly circle were integrated for amplified signals, which were tested by a fluorescence resonance energy transfer (FRET) assay. NaYF4:Yb,Tm/Er UCNPs and Ti3C2 nanosheets were used as the energy donor-acceptor pair. By employing 1:2 ratio of donor-acceptor, the energy transfer efficiency between NaYF4:Yb,Tm/Er UCNPs and Ti3C2 nanosheets could reach 90%, which enhanced signal-to-background ratio. Combining the benefits of dual amplification and efficient energy transfer on miRNAs detection, this assay exhibited a linear range from 5 fM to 100 pM for miRNA-21 and miRNA-10b. Moreover, this assay was applied to estimate the expression of miRNA-21 and miRNA-10b in human hepatoma and hepatocyte cell lines. Therefore, this FRET-based SDDA strategy has been used for highly sensitive detection of multiple miRNAs in cell lysate and facilitates the development of efficient biosensor platform.