A Multitargeted Electrochemiluminescent Biosensor Coupling DNAzyme with Cascading Amplification for Analyzing Myocardial miRNAs.

Several circulating miRNAs are associated with the pathogenic process of acute myocardial infarction (AMI). Thus, analyzing myocardial miRNAs in the circulatory system is important for the diagnosis and treatment of AMI, especially for early-stage diagnosis. Based on the characteristics of myocardial miRNAs, an ultrasensitive and multitargeted electrochemiluminescence (ECL) sensing platform was developed with a versatile probe that can couple DNAzyme with hybridization chain reaction amplification. The target miRNA and auxiliary chains form a circular unit that shears the versatile probe hairpin, and the products subsequently trigger cascading amplification; a long strand of dsDNA is then generated with many C-rich sequences that can undergo in situ reductions to generate ECL luminophore silver clusters. Using this strategy, three myocardial miRNAs are successfully detected with a detection limit as low as 29.6 aM (S/N = 3). Notably, our method can detect myocardial miRNA groups composed of multiple related circulating miRNAs with high selectivity over interfering miRNAs in blood. This is extremely important for solving the problem of diverse and low abundance of infarct-associated miRNAs. Our strategy pioneers a new idea of miRNA detection, and given its versatility and sensitivity, it is promising for the diagnosis of multigene-regulated cardiovascular diseases.