Precise quantification of microRNAs based on proximity ligation of AuNPs-immobilized DNA probes.

MiRNAs are critical regulators of target gene expression in many biological processes and are considered promising biomarkers for diseases. In this study, we developed a simple, specific, and sensitive miRNA detection method based on proximity ligation reaction, which is easy to operate. The method uses a pair of target-specific DNA probes immobilized on the same gold nanoparticles (AuNPs), which hybridize to the target miRNA. Hybridization brings the probes close together, allowing the formation of a continuous DNA sequence that can be amplified by Quantitative Real-time PCR (qPCR). This method eliminates the need for complex reverse transcription design and achieves high specificity for discriminating single base mismatches between miRNAs through a simple procedure. This method can sensitively measure three different miRNAs with a detection limit of 20 aM, providing high versatility and sensitivity, even distinguishing single-base variations among members of the miR-200 family with high selectivity. Due to its high selectivity and sensitivity, this method has important implications for the investigation of miRNA biological functions and related biomedical research.