Target-Triggered Self-Assembly of Single-Band Red Emission of Upconversion Nanoparticle-Based Dual-Signal Fluorescent Probes for Sensitive and Accurate Determination of microRNAs

MicroRNAs (miRNAs) are small molecules with significant regulatory functions that have served as biomarkers for the early diagnosis of disease. Accordingly, it is purposeful to develop a rapid, targeted assay for the sensitive, selective, and determination of target miRNAs. Single-band red emission of upconversion nanoparticles (UCNPs) offer high photostability, large anti-Stokes shifts, and low background. Additionally, improving the accuracy via dual-signal fluorescence is also effective for reducing false positive signals induced by background. Herein, taking advantage of the single-band red emission of UCNPs and DNA complementary nanotechnologies, a target-triggered self-assembled dual-signal response biosensor via a strand displacement cascade is reported. The reported approach was used for the determination of miRNA-222 (a model analyte) in serum and the results were similar to those obtained by the polymerase chain reaction (PCR). The spiked recoveries were from 92.5 to 108.4%, indicating that this biosensor has potential for accurate and sensitive determination of miRNAs in biological samples.