Dumbbell probe-bridged CRISPR/Cas13a and nicking-mediated DNA cascade reaction for highly sensitive detection of colorectal cancer-related microRNAs

Colorectal cancer (CRC) is a leading cause of cancer-related deaths globally, necessitating the development of sensitive and minimally invasive diagnostic approaches. In this study, we present a novel diagnostic strategy by integrating dumbbell probe-mediated CRISPR/Cas13a with nicking-induced DNA cascade reaction (DP-bridged Cas13a/NDCR) for highly sensitive microRNA (miRNA) detection. Target miRNA triggers Cas13a-mediated cleavage of the dumbbell probe, releasing an intermediate strand that hybridizes with a methylene blue-labeled hairpin probe on the electrode surface. Nicking enzyme cleaves the formed duplex DNA, triggering a cascade reaction that amplifies the electrochemical signal. Under optimized conditions, the method demonstrates a detection limit of 8.26 fM for miRNA-21, with reliable specificity and long-term stability. Furthermore, integration with machine learning models using multiple miRNA markers improved diagnostic accuracy, differentiating CRC from colorectal polyps and healthy controls with 100% accuracy in clinical validation cohorts. This study highlights the potential of DP-bridged Cas13a/NDCR as a sensitive and accurate diagnostic tool for CRC.