Cascade CRISPR/Cas12a and DSN for the electrochemical biosensing of miR-1246 in BC-derived exosomes

•The method exhibits high specificity and sensitivity.•The method can diagnosis the BC patients. MiR-1246 in breast cancer-derived exosomes was a promising biomarker for early diagnosis of breast cancer(BC). However, the low abundance, high homology and complex background interference make the accurate quantitative detection of miR-1246 facing great challenges. In this study, we developed an electrochemical biosensor based on the subtly combined of CRISPR/Cas12a, double-stranded specific nuclease(DSN) and magnetic nanoparticles(MNPs) for the detection of miR-1246 in BC-derived exosomes. Ascribed to the good synergistic effect of DSN, Cas12a and MNPs, the developed electrochemical biosensor exhibited excellent performance with the linear range from 500 aM to 5 pM, and the detection limit as low down to about 50 aM. The target-specific triggered enzyme-digest activity of DSN and Cas12a system, as well as the powerful separation ability of MNPs ensure the high specificity of developed electrochemical biosensor which can distinguish single base mismatches. In addition, the developed electrochemical biosensor has been successfully applied to detect miR-1246 in blood-derived exosomes and realize distinguishing the BC patients from the healthy individuals. It is expected that the well-designed biosensing platform will open up new avenues for clinical liquid biopsy and early screening of breast cancer, as well as provide deeper insights into clinical oncology treatment.