A simple, wedged DNA walker electrochemical biosensor-enabled DNA logic system for miRNA diagnostics

DNA logic-gated operations enhance the efficiency of analyzing multiplex nucleic acid inputs, attracting significant attention. However, fully integrating DNA logic gates with diverse computational functions and signal amplification for biomedical diagnosis remains a challenge. In this study, we introduce a simple, wedged DNA walker-based amplified electrochemical method for miRNA detection. This method serves as the fundamental unit for constructing various logic circuits, enabling multiplex miRNA analysis. During the wedged DNA walking process, target miRNA initiates strand displacement polymerization, generating numerous DNA intermediate (M) strands that function as single-legged walkers. The immobilization probe on the track includes a wedge segment complementary to the intermediate strand, preventing its dissociation. The fuel strand, modified with ferrocene (Fc), drives the target strand to undergo branch migration and move progressively along the track. The stepwise movement of the intermediate strand enables the accumulation of Fc molecules, resulting in a significantly increased current response for target miRNA detection. Furthermore, by controlling logic functions through input-triggered cascade strand displacement reactions, we successfully establish NOT, AND, OR, NAND, and NOR logic gates. This DNA logic system can be extended to multi-input modes, offering great potential in DNA computing, multiplex analysis, and clinical diagnosis.