Highly sensitive homogeneous electrochemiluminescence biosensor for microRNA-21 based on cascaded signal amplification of target-induced hybridization chain reaction and magnetic assisted enrichment

MicroRNA-21(miRNA-21) can act as a novel biomarker in early stage of acute kidney injury (AKI). The development of simple but sensitive miRNA-21 detection technology is helpful for prevention and treatment of AKI. In this work, based on the cascaded signal amplifications of the target-induced hybridization chain reaction (HCR) and magnetic assisted enrichment, a highly sensitive homogeneous electrochemiluminescence (ECL) biosensor for miRNA-21 detection had been developed. Firstly, capture probe H1 (CPH1) had been modified on magnetic beads (MBs) which could capture target (miRNA-21) and trigger HCR amplification to produce long strand dsDNA in the homogeneous solution. Ru(phen) 3 2+ could be embedded into the grooves of dsDNA and played the role of luminous tag, which could be separated by magnetic easily to realize the enrichment. Then the enriched products had been dissolved in the buffer solution and the ECL signal could be detected easily. The ECL intensity had a linear correlation with the logarithm of miRNA-21 concentration in the range of 1.0 fM-1.0 nM, the detection limit was 0.14 fM. The method developed in this work showed well sensitivity, specificity, which had been applied to detect miRNA-21 in urine of AKI patients with satisfied results.