Y-shaped walker with abundant recognition domians mediated ultrasensitive electrochemical biosensor for miRNA-21 detection

Herein, an ultrasensitive electrochemical biosensor was constructed by a high-efficiency Y-shaped walker with abundant recognition domains (YSWARD) for microRNA-21 (miRNA-21) detection. Once target miRNA-21 induced the assembly of Y-shaped DNA nanostructure (YSDN) through a catalytic hairpin assessbly (CHA), amounts of the YSWARD could be synthesized with the assistance of padlock via rolling circle amplification (RCA). Impressively, the YSWARD exhibited much higher cleavage efficiency (2.81 x 109) which was at least ten times more than that of conventional Y-shaped walker with three recognition domains (2.36 x 108). As a proof of concept, the YSWARD was adopted to construct electrochemical biosensing platform that achieved ultrasensitive detection with a detection limit of 10.6 aM for target miRNA-21, which carved out promising potential for exploring novel DNA walker platforms to apply in sensitive detection of biomarkers and early diagnosis of diseases.