Low background electrochemical sensor based on HCR towards acute myocardial infarction-specific miRNA detection

Acute myocardial infarction (AMI) accounts for a significant proportion of global fatalities, and early detection is crucial for improving patient outcomes. However, current diagnostic methods often struggle to detect AMI in its early stages. Herein, we present an electrochemical sensor utilizing a fractal gold (FracAu) electrode and hybridization chain reaction (HCR) amplification technology to detect AMI-specific microRNAs (miRNAs). When the target sequence was added, the HCR was triggered, leading to the formation of a long-nicked DNA double helix that efficiently captured a larger quantity of positively charged RuHex molecules, resulting in significant electrochemical signal amplification. More importantly, to avoid false positive signals, exonuclease I (Exo I) was introduced to selectively cleave single-stranded DNA (ssDNA) probes. These ssDNA probes, underwent random hydrolysis from hpDNA probes, could hybridize with helper DNA1 in the absence of the target, initiating the HCR process and producing a false positive signal. The inclusion of Exo I effectively avoided false positive signals and reduced background noise. Under optimized conditions, the fabricated sensor exhibited significant sensitivity and selectivity, showing a broad linear detection range from 10 pM to 10 nM and a low limit of 0.9 fM. The fabricated electrochemical sensor also successfully detected AMI-specific miRNA in real serum samples, underscoring its diagnostic promise. By providing a reliable tool for early detection, the innovative sensor holds significant potential in combating global cardiovascular disease-related mortality rates.