Label-free homogeneous electrochemical sensing strategy for microRNA detection

Sensitive detection of ultra-low abundance microRNA is an urgent task, especially in disease prediction and diagnosis. Herein, a homogeneous electrochemical sensing strategy was developed for the precise detection of microRNA-21. The target strands in samples were recognized and captured by the modified magnetic beads. Followed by the hybridization chain reaction (HCR) process, many electrochemical reactive molecules were gathered to the surface of magnetic beads by embedding to the ravine of double strands. And the apparent electrochemical signal could be obtained after magnetic separation and exonuclease digestion process. The HCR assisted signal amplification greatly enhanced the signal distinction while the non-modified electrode avoiding the modification fluctuation. The constructed biosensor showed favorable performance in the detection of microRNA-21 with a wind linear range from 1fM to 10 nM. And the detection limit of this biosensor was around 0.17 fM, which exhibit great specificity and reproducibility in complex sample analysis.