DNA self-assembled FeNxC nanocatalytic network for ultrasensitive electrochemical detection of microRNA

Accurate detection of microRNA (miRNA) is challenging but essential for disease diagnostics and therapeutics. To meet the high demands of miRNA analysis, we proposed a highly sensitive and specific electrochemical strategy based on duplex-specific nuclease (DSN)-assisted target recycling and DNA self-assembled FeN x C nanocatalytic network for precise quantitation of miRNA-21 as a model. FeN x C nanospherical catalyst with high peroxidase-mimicking activity was synthesized through high-temperature pyrolysis and modified with DNA. The identification of miRNA-21 by elaborately designed capture probe triggered DSN-assisted target recycling. Subsequently, self-assembled FeN x C nanocatalytic network was constructed on the sensor surface through DNA hybridization reaction, whose signal response was demonstrated to be 4.272-fold higher than the single layer of FeN x C. By virtue of such cascade signal amplification, ultrasensitive electrochemical detection of miRNA-21 was realized in a dynamic range of 0.5 fM - 1 pM with a detection limit of 0.2805 fM. Additionally, the proposed strategy exhibited high specificity for miRNA-21 and practical applicability in real sample analysis, demonstrating promising potential for the reliable miRNA analysis in disease diagnosis and therapy applications.