Ultrasensitive and Specific Multi-miRNA Detection Based on Dual Signal Amplification

Abstract The expression level of miRNAs is closely related to the occurrence and development of various human diseases. However, they are difficult to be quantified due to the inherent nature of low expression in cells and plasmid. Simultaneous detection of multi-miRNA is more challenging. In this paper, we developed an ultrasensitive and specific multiple miRNAs detection strategy based on strand displacement amplification (SDA) reaction and analogical catalytic hairpin assembly (ACHA) reaction. The target miRNA specifically binds with the template and initiates the SDA reaction to produce abundant amplification products (triggers), which take part in the ACHA reaction on the electrode surface resulting in a decreased electrochemical response. With the help of dual amplification strategies, the linear relationship between the electrochemical signal and miRNA-122 and miRNA-21 concentration was in the range of 0.1 fM to 10 fM, with the detection limit of 0.012 fM and 0.075 fM, respectively. The electrochemical sensor can also be applied to detect other miRNA just by changing the template strands. In addition, the electrode can be regenerated by incubating with specific DNA strands.