Construction of the fiber optic LSPR sensor for highly sensitive detection of miR-103 by a dual signal enhancement strategy based on the hot-spot effect and HexSG4 catalysis

MicroRNAs are important tumor biomarkers. How to effectively detect them by sensors is a challenge because of their extremely low concentrations. We proposed a dual signal enhancement strategy to develop the fiber optic (FO) localized surface plasmon resonance (LSPR) sensor for the highly sensitive detection of miR-103. It included two stages, one was to obtain the hot-spot by constructing the multimer structure, AuNP-spacer- AuNPs, and another was the combination of capturing miR-103 by the probe and catalytic amplification by Hexagonal star G-quadruplex catalyzing 4-chloro-1-naphthol to generate benzo-4-chlorohexadienone, which deposited on the AuNPs, resulting in the generation of LSPR peak redshift. The parameters of the preparation and detection application were systematically optimized. The redshift values had a good linear relationship with the logarithms of miR-103 concentrations, with high R2 0.9973, wide detection range 102 - 107 fM, and low LOD 6.4 fM. The method had high specificity, repeatability, and reproducibility, and was also successfully validated with real samples. Therefore, the dual signal strategy for constructing FO LSPR sensors can achieve the high sensitivity detection of extremely low concentration of MicroRNAs, which will have great application prospects in medicine and life science.