A POCT assay based on commercial HCG strip for miRNA21 detection by integrating with RCA-HCR cascade amplification and CRISPR/Cas12a

A point-of-care testing (POCT) assay based on commercial HCG strip was proposed for miRNA21 detection by integrating RCA-HCR cascaded isothermal amplification with CRISPR/Cas12a. Three modules were integrated in the proposed platform: target amplification module composed of rolling circle amplification (RCA) cascaded with hybridization chain reaction (HCR), signal transduction module composed of CRISPR/Cas12a combined with HCG-agarose gel beads probes, and signal readout module composed of commercial HCG strips. The proposed RCA-HCR-CRISPR/Cas12a-HCG strip assay for miRNA21 detection had high sensitivity, and the limit of detection was as low as 37 fM. The proposed assay showed excellent specificity for miRNA21, as other miRNAs did not caused interference for detection. The recoveries of miRNA21 were ranged from 89.0 to 118.0%. The intra-batch and inter-batch coefficient of variation (CV) were 10.1-13.4% and 11.9-14.5%, respectively, which indicated a high accuracy and precision, and the serum matrix did not cause any interference. With the advantages of low-cost, high sensitivity, visualization, and easy popularization, the proposed assay is expected to provide a powerful tool for early diagnosis of tumor disease miRNA, especially in resource-limited areas.