Highly sensitive and specific electrochemical biosensor for microRNA-21 detection by coupling catalytic hairpin assembly with rolling circle amplification

Background: MicroRNA plays a significant role in gene regulation and is usually regarded as an important biological marker. Electrochemical biosensors are excellent tools for microRNA detection. Methods: In this experiment, we take miRNA-21 as a target, combining catalytic hairpin assembly (CHA) and rolling circle amplification (RCA) as a dual signal amplification strategy for the detection of microRNA in an electrochemical biosensor. Results: This strategy has a good linear range of 0.5–12 500 pmol of microRNA. The limit of detection (LOD) for miRNA is as low as 290 fmol, showing excellent performance. Finally, this method has been successfully applied to the detection of miRNA-21 from HeLa cells. Conclusion: This method can be applied not only for microRNA detection with high sensitivity and speed, but can also detect small molecules and proteins combined with aptamers.