Sensitive and enzyme-free fluorescence polarization detection for miRNA-21 based on decahedral sliver nanoparticles and strand displacement reaction

Abstract

A highly sensitive method for miRNA-21 analysis and detection has been developed, which relied on the enhanced effect of Ag₁₀NPs, combined with the principle of strand displacement reaction to achieve asymmetric signal amplification. The detection probe was composed of Ag₁₀NPs and two self-assembled complementary nucleic acid strands by thiol groups. The nucleic acid strand with a fluorescent group (named 2-FAM) was initially complementary to the chain in contact with Ag₁₀NPs (named 1-SH), then it was replaced by a strand displacement reaction with miRNA-21, which exposed the toehold to react with the nucleic acid strand (named 3-fuel), and miRNA-21 was finally released into the next cycle of amplification, which eventually results in a significant increase in the fluorescence polarization signal change value. The linear range of this method was 100 pM to 16 nM while the detection limit was 93.8 pM, fast and sensitive detection could be achieved in 40 min. This method showed a certain anti-interference ability in the buffer and real biological samples, and achieved fast, accurate and sensitive detection.