DNAzyme based dual signal amplification strategy for ultrasensitive myocardial ischemia related MiRNA detection.

Abnormal expression of microRNAs (miRNAs) is closely associated with a diverse of important biological processes, such as metastasis, myocardial ischemia and progression. Development of a facile and enzyme-free method for sensitive miRNA detection remains a huge challenge. Herein, we proposed a cross-catalytic circuit for trace miRNA detection by facilely integrating hairpin catalytic reaction (HCR) and DNAzyme biocatalyst through an ingenious feedback loop. The DNAzyme functional part was originally grafted in the designed hairpin structure probes, which would be released from hairpin structure probe and induce subsequent signal amplification after the recognition of target miRNA and the formation of double-strand DNA products. Through the dual signal amplification, the method exhibited a favorable detection sensitivity with a low of detection of 56 fM. These two indispensable catalytic reactions play vital roles in executing high-performance signal amplification, as demonstrated experimentally and theoretically.