Magnetic Multipedal DNA Walking Nanomachine Driven by Catalytic Hairpin Assembly

miRNAs in circulating blood have been regarded as promising biomarkers for the diagnosis of a series of diseases. Development of ultrasensitive, reliable, and convenient methods for miRNA assay is of great significance. Herein, we present a novel electrochemical sensing strategy. The assembly of DNA walker strands on membrane-coated nanomaterials, target-mediated recycling activation, and electrochemical signal enrichment are integrated. Multipedal DNA walking with magnetic cores and a catalytic hairpin assembly at the electrode lead to the increase of electrochemical response, which can be used to probe initial target miRNA. This DNA walking nanomachine shows enhanced signal amplification efficiency and facile magnetic separation steps. It enables rapid analysis of miRNA at the attomole level and performs satisfactorily in samples of human circulating blood. Given the powerful sensitivity, facile operation, and excellent specificity, this magnetic multipedal DNA walker provides a promising way to determine miRNA level for biomedical applications.