Stochastic RNA Walkers for Intracellular MicroRNA Imaging

Nucleic acid-based machines have sparked tremendous attention because of their potential applications in biosensing, drug delivery, and biocomputing. Herein, we construct an enzyme-propelled stochastic RNA walker that autonomously walks on a single wall carbon nanotube (SWCNT)-based one-dimensional (1D) track for miRNA imaging in living cells. Driven by duplex-specific nuclease (DSN) with the capability of selective digestion of DNA in the DNA/RNA heteroduplexes, the RNA walker enables autonomous and progressive walk on the SWCNTs, producing amplified signal outputs. As a result, this DSN-powered stochastic RNA walker with high target-recycling kinetic achieves prominent detection performance of miRNA analysis, showing a linear range from 5 fM to 10 pM with a limit of detection of 1.67 fM and one-base mismatch discrimination. Finally, we demonstrated that this nanomachine can be applied for intracellular miRNA imaging.