Detection of microRNAs using toehold-initiated rolling circle amplification and fluorescence resonance energy transfer.

Detection of microRNAs (miRNAs) in cells improves our understanding of their physiological functions and facilitates exploration of their roles diseases. The toehold-mediated strand displacement reaction initiates rolling circle amplification (RCA) to achieve signal amplification of the specific miRNA; This process is named as toehold-initiated RCA (TIRCA). The product of TIRCA was ligated to two DNA probes, which were modified with 6-carboxyfluorescein and carboxytetramethylrhodamine, respectively. Qualitative detection of miRNAs was successfully achieved by combining the fluorescence aggregation enhancement effect with fluorescence resonance energy transfer generated by the proximity of the two fluorescent dyes. Thus, this approach helps us analyze the roles of miRNAs in human disease more accurately.