Logic-Gate-Controlled Positive-Feedback DNAzyme Catalytic Circuit for One-Pot Detection of Dual miRNA.

Molecular logic gate circuits show promise for decoding multibiomarker patterns in diagnostics, but achieving precise logic control and high-fidelity amplification remains challenging. Here, we develop a logic-gate-controlled positive-feedback DNAzyme circuit for one-pot detection of dual miRNA (termed DECODER). DECODER utilizes an engineered dual-catalytic-core 8-17 DNAzyme as the logic switch. Each core is specifically activated by a target miRNA to cleave one of the two rA sites on a designed probe. Fluorescence is emitted only upon dual cleavage, enabling the AND logic operation. The cleavage generates new 3' ends that act as primers to initiate two independent RCA reactions. The programmed RCA products hybridize to form E6 DNAzymes, which cleave more probes and establish a self-sustaining positive-feedback loop, amplifying the initial AND logic signal with high fidelity. DECODER achieves a detection limit of 79.8 fM within 75 min. In serum tests, it diagnosed early stage nonsmall cell lung cancer with 88.3% accuracy, demonstrating strong translational potential.