MED: Multiplexed, Entropy-Driven Catalysis, Single-Nucleotide-Resolved ctDNA Detection

Real-time circulating tumor DNA (ctDNA) monitoring allows early detection of residual disease, dynamic assessment of treatment response, and identification of resistance, highlighting the demand for scalable point-of-care tests that allow mutations to be resolved. Here, we introduce MED, a multiplexed, entropy-driven catalysis (EDC), single-nucleotide-resolved ctDNA detection assay, enabling enzyme-free nucleic-acid amplification and visual detection of ctDNAs. The recognition of ctDNA depends on the initiation of EDC and magnetic separation with single-nucleotide resolution. The assay leverages a triple amplification strategy to amplify the recognition events of trace ctDNAs, involving EDC, Ag⁺ release from silver nanoparticles (AgNPs) catalyzed by H₂O₂, and urea hydrolysis catalyzed by urease, for colorimetric readout of pH changes. For 40 blood specimens (20 colorectal cancer, 10 benign colorectal adenoma, and 10 normal controls), the assay simultaneously detected the presence of a panel of four kinds of ctDNAs in 100% concordance with sequencing and demonstrated over 85% accuracy in distinguishing between cancer and noncancer. Further, integrated into bioactive paper and smartphone readout, MED provides rapid (sample-to-answer time within 45 min), multiplexed, and accessible point-of-care results, with over 70% accuracy. Its unique capacity surpasses existing detection platforms, presenting robust clinical potential to enhance early diagnosis, enable dynamic monitoring of cancer progression, and guide personalized therapeutic interventions.