Multiselective Recognition of Metal Ion–Nucleic Acid Complexes by CRISPR/Cas12a and Quantum Dots Enables the Profiling of Circulating Tumor DNA in Breast Cancer

to quench the quantum dot fluorescence. This label-free assay achieved attomolar sensitivity within 30 min without enzymatic preamplification or complex nucleic acid extraction. Importantly, the platform exhibits excellent sequence selectivity, enabling precise discrimination of single-base mutations against closely related sequences. Validation of 42 clinical plasma samples achieved 100% diagnostic specificity for BC. For staging, the platform yielded a sensitivity of 100%, a specificity of 92.3%, and an area under the curve of 0.978. With its exceptional sensitivity and operational simplicity, this platform offers a promising approach for precise ctDNA-based BC detection and staging, demonstrating significant translational clinical potential.