Enhanced red emission of upconversion nanoparticles via Li+ and Tm3+ codoping and active core-shell construction for sensitive detection of miRNAs
The overexpression of microRNA-222 (miRNA-222) is closely related to many human diseases, so the development of biosensors to detect this biomarker will contribute to the diagnosis of related diseases. Here, a simple, sensitive and specific fluorescence assay for the detection of miRNA-222 was developed using red-emitting upconversion nanoparticle (UCNP) as the donor and a DNA hairpin with black hole quencher-2 (BHQ-2) as the acceptor. Li + and Tm 3+ -doped UCNP with a strong emission peak at 654 nm was obtained by changing the doped ion ratio and constructing core-shell structures. Under optimal conditions, the linear range for detecting miRNA-222 is 0.5–2.5 nM and the limit of detection is as low as 0.077 nM without any complicated amplification strategy. Finally, the proposed assay was applied for the detection of miRNA-222 in serum samples. The results obtained were similar to those of the standard method, and the spiked recoveries were in the range of 97.62%–102.14 %, suggesting that the proposed method has practical value in a complex biological sample matrix.
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