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.