Rapid and sensitive detection of circulating tumor DNA <i>via</i> a CRISPR/Cas12a-based catalytic hairpin assembly

Cancer is one of the major diseases that endanger the human health. Circulating tumor DNA (ctDNA) is an ideal biomarker for the real-time monitoring of cancer. In the present work, a rapid and sensitive assay coupled with CRISPR/Cas12a and CHA (Cas12a-CHA) was constructed for the detection of ctDNA. We designed and prepared a trigger, which was the substrate of Cas12a. On the addition of ctDNA, crRNA-guided ctDNA activated the <i>trans</i>-endonuclease activity of Cas12a. After being activated, Cas12a exhibited a high <i>trans</i>-cleavage activity on the trigger, which resulted in a decrease in fluorescence. Owing to this design, the Cas12a-CHA assay enabled the sensitive detection of ctDNA with a linear range of 10 fM to 50 pM. Furthermore, a limit-of-detection of 5.8 fM was achieved within 40 min. Besides, the proposed assay had an excellent base mismatch recognition ability and worked well in human serum samples. Conclusively, this detection platform holds significant potential for application in early cancer diagnosis.