Light-Activated Nanodevice for On-Demand Imaging of miRNA in Living Cells via Logic Assembly.

Low-abundance biomarker amplification detection systems have been widely used to detect miRNAs; however, "always active" systems are insufficient for high spatial and temporal control of miRNAs. Here, we constructed a light-activated nanodevice (LAN) based on DNA nanotechnology for high spatial and temporal precision detection of low-abundance miRNA. Light-activated hairpin probes and triple-helix molecular switches were modified on the surface of gold nanoparticles (AuNPs) to trigger miRNA on-demand imaging analysis by UV light activation. In the presence of both UV light and miRNA, the LAN releases hairpin DNA and completes the hybridization chain reaction (HCR) with the conformation-altered triple-helix molecular switch, enabling fluorescence imaging of low-abundance miRNAs in living cells. The current work provides an opportunity to develop light-activated signal amplification sensors that can accurately image miRNAs on-demand in both temporal and spatial dimensions.