A simple and ultrasensitive electrochemical biosensor for detection of microRNA based on hybridization chain reaction amplification

• We combined HCR with streptavidin signal enhancement to presents a simple and rapid platform for microRNA detection.
• The method displayed excellent sensitivity and specificity for detection of microRNA.
• The fabricated biosensor could be applied to detect microRNA spiked into human total RNA samples successfully.

MicroRNAs (miRNAs) play vital roles in regulating gene expression and cellular processes. Dysregulation of miRNAs has been associated with a variety of diseases, which make them promising biomarkers. In this work, a simple and ultrasensitive electrochemical biosensor was developed for detection of target miRNA using DNA-based hybridization chain reaction (HCR) and biotin-strepavidin based amplification. In the presence of target miRNA, the hairpin DNA capture probes immobilized on gold electrode surface were opened. Then DNA initiator strands hybridized with the opened capture probes and triggered HCR, finally, a long nicked double-helix DNA structure was developed. Streptavidin is employed for signal amplification via binding with biotin labeled on the two hairpin DNA probes which take part in the HCR. The proposed biosensor presented a high sensitivity for determination of target miRNA down to 0.56 fM with a linear range from 1 fM to 100 pM and high specificity that discriminates target miRNA from mismatched miRNAs. The method was successfully applied to the determination of miRNA spiked into human total RNA samples. Therefore, the biosensor might have potential clinical application for miRNA detection in biomedical research and clinical diagnosis.