CRISPR/Cas12a-coupled multiplexed amplification system for ultrasensitive detection of miRNA-155

Abstract

miRNA plays an important role in gene regulation and can be an effective biomarker for disease diagnosis. Herein, a new miRNA detection platform based on CRISPR/Cas12a-coupled multiplexed amplification system is developed. In this strategy, miRNA-155 acts as an intermediary to trigger the recombinase polymerase amplification (RPA). Due to the introduction of endonuclide recognition sites in the amplification template, the resulting double-stranded DNA (dsDNA) can in turn initiate a strand replacement reaction (SDA), generating a great deal of single-stranded DNA (ssDNA). The ssDNA can directly unlock the trans-cleavage activity of CRSIPR/Cas12a, and the process is independent of PAM sites. Subsequently, the activated Cas12a trans-cleaves nearby signaling molecules, outputting a fluorescence/visualization signal. This method achieves miRNA detection as low as 68.69 fM, with a linear range of 200 fM to 1nM, and shows good selectivity and repeatability. Meanwhile, the target of 10 pM can be distinguished by the naked eye. Moreover, the proposed method can achieve miRNA-155 detection in complicated cell extracts. The excellent detection sensitivity is mainly due to the integration of two amplification techniques, while the CRISPR/Cas12a system enables fast and accurate visual detection. More importantly, the actual detection results are consistent with standard methods (RT-qPCR), indicating that the CRISPR/Cas12a-coupled multiplexed amplification system is reliable and has potential clinical application value.