Direct and accurate miRNA detection based on CRISPR/Cas13a-triggered exonuclease-iii-assisted colorimetric assay

The abnormally expressed microRNAs (miRNAs) serve as crucial indicators for disease diagnosis and are strongly associated with the progression of various diseases. The quantification of miRNAs is highly significant for the clinical diagnosis and treatment of various types of cancers. This study utilizes the CRISPR/Cas13a system, which combines CRISPR RNA (crRNA) and CRISPR-associated Cas13a, to recognize the miRNA directly and specifically, thus activating the trans-cleavage activity of Cas13a. By integrating the CRISPR-Cas13a system with an exonuclease-iii (Exo-iii)-assisted chain cleavage of silver ions (Ag+)-aptamer and an Ag+ -based color reaction, a method for the detection of miRNA that is specific and sensitive is developed. This approach demonstrated exceptional sensitivity in detecting miRNA, with a low detection limit of 5.12 fM. Moreover, the suggested method was effectively utilized to precisely measure the amount of miRNA in intricate biological samples, demonstrating its practical applicability. Furthermore, due to its elevated sensitivity and simple probe design and fluorophore labeling, the suggested colorimetric technique holds great potential for use in clinical diagnostics.