Dynamic Monitoring of MicroRNA-DNA Hybridization Using DNAase-Triggered Signal Amplification

Dynamically monitoring microRNA (miRNA) DNA reactions is critical for elucidating various biological processes. However, traditional strategies fail to capture this dynamic event because the original targets are preamplified. In the present study, we developed an amplification-free strategy for real-time monitoring of miRNA DNA hybridization that integrates the advantages of both duplex-specific nuclease (DSN)-triggered signal amplification and single-stranded DNA probe coating facilitated by reduced graphene oxide. DSN-mediated miRNA recognition was found to consist of two phases: hybridization and hybridization cleavage. In the presence of miRNA and DSN, hybridization of a 22-mer miRNA DNA could be completed within 7 min by observing the angle increase in a surface plasmon resonance (SPR) biosensor. The subsequent hybridization-cleavage process could be visualized as a gradual SPR angle decrease that occurred until all coated probes were hydrolyzed. In addition, for miRNA-21 detection, the proposed linear signal amplification assay demonstrated a sensitivity of 3 fM over a dynamic range of S orders of magnitude.