Dual-signal fluorescence detection of miRNA based on nano-gold molecular beacon and in-situ generated silver...

In this work, a new dual-signal fluorescence strategy based on nano-gold molecular beacon (MB) and in-situ generated silver nano-clusters (NCs) coupled with multiple amplification technique was developed for sensitive detection of miRNA (let-7b). miRNA can recognize both hairpin probe (HP) and auxiliary DNA, inducing dual-cycle amplification-process to release plenty of DNA S2. As the report probe carboxyfluorescein (FAM) was modified on Au nanoparticles (AuNPs), the fluorescent signal was quenched due to the fluorescence resonance energy transfer (FRET). After DNA S2 opened the hairpin structure of the report probe, the fluorescence was recovered for target detection. Furthermore, the amplification product S2 can also trigger hybrid chain reaction (HCR) on silicon spheres, which opened numerous hairpin structure (HP1 and HP2) and exposed C-rich sequences, so abundant nanosilver clusters can be in situ synthesized for fluorescence detection of target. This method combines multiple amplification technique with two fluorescent probes to achieve simple, rapid and sensitive double-detection of target, which greatly improves the accuracy of bioanalysis and has great application potential in clinical detection.