Electrochemical biosensor based on efficient target-trigger T-structure recycling with dual strand displacement amplification for sensing miRNA-155

In this work, a novel label-free and signal-off electrochemical biosensor based on efficient target-trigger T-structure recycling with dual strand displacement amplification (T-DSDA) was constructed for sensitive detection of miRNA-155 that related to cardiovascular diseases. Compared with traditional SDA, the proposed strategy not only accomplished simple polymerization and shearing of dsDNA without continuous consumption of temple DNA , but also ingeniously designed two analogous sequences that produced double cleavage sites, thereby obtaining extensive output DNA for further cleaving Y-structure assembled on electrode with significantly improved target conversion efficiency. Since the redox probe methylene blue (MB) attach to Y-structure via electrostatic interaction and tessellation, an obviously decreased current with a typical signal-off mode could be acquired for sensing miRNA-155 in the assistant of DNAzyme cleavage recycling. As a result, the electrochemical biosensor realized the rapid and sensitive detection of miRNA-155 with a low detection limit down to 166.7 fM. In addition, the biosensor displayed a strong anti-interference ability in bovine whole blood, and thus was expected to be applied to detect blood samples of various miRNA-155 related diseases in clinical diagnosis.