A Disposable CRISPR-Nanozyme Electrochemical Biosensor for Rapid and Sensitive Detection of Breast Cancer Circulating Tumor DNA.

Circulating tumor DNA (ctDNA) serves as a promising next-generation biomarker for noninvasive cancer screening and monitoring. In this work, we report an electrochemical biosensor for ctDNA detection. The sensor is constructed based on the synergistic integration of CRISPR/Cas12a and PB-Au NPs. CRISPR/Cas12a provides precise target recognition and triggers trans-cleavage, while the nanozyme enables strong signal amplification through its catalytic activity. Using a disposable carbon-fiber paper as the biosensing interface, we developed this sensitive detection strategy. On this interface, a PB-AuNP-labeled single-stranded DNA reporter is immobilized. In the presence of target ctDNA, activated Cas12a cleaves the reporter, releasing the nanozyme and resulting in a quantifiable decrease in the TMB oxidation current. This dual-amplification strategy achieves a detection limit of 860 aM (S/N = 3) with a linear range from 1 fM to 1 nM. Overall, this approach provides a satisfactory demonstration toward the realization of a low-cost and highly sensitive biosensor for ctDNA detection.