CRISPR/Cas12a and Au@UiO-66 nanozyme synergistic dual amplification-based electrochemical biosensor for ultrasensitive ctDNA detection.

Breast cancer, a globally prevalent malignancy in women, requires early diagnosis to improve patient outcomes, where ctDNA serves as a key biomarker. In the present study, an electrochemical biosensor based on CRISPR/Cas12a and Au@UiO-66 nanozyme synergistic dual amplification was developed to achieve ultrasensitive detection of breast cancer marker ctDNA. Au@UiO-66-modified ssDNA probes were anchored to the gold electrode via thiol groups. The intact ssDNA probe anchors Au@UiO-66 nanozyme to the electrode, where its peroxidase-like activity efficiently catalyzes H2O2 reduction to generate amplified reduction peak currents. Target ctDNA activates Cas12a's trans-cleavage capacity by binding specifically to crRNA. Under the presence of the target, Au@UiO-66 nanozymes are released, resulting in a discernible drop in the peak current linked to H2O2 reduction. Benefiting from the optimized experimental conditions, the biosensor demonstrates a broad linear detection range (from 10 fM to 10 nM) for the target ctDNA, along with an exceptionally low detection limit of 6.14 fM. Successful detection in human serum samples demonstrates its practicality. The platform's high specificity is attributed to the programmable crRNA design, enabling detection of specified DNA sequences and showcasing significant adaptability for diagnosing multiple genetic targets, highlighting its potential in clinical cancer diagnosis.