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_xC nanocatalytic network for precise quantitation of miRNA-21 as a model. FeN_xC 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_xC 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_xC. 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.

准确检测 microRNA (miRNA) 具有挑战性，但对于疾病诊断和治疗至关重要。为了满足 miRNA 分析的高要求，我们提出了一种基于双链特异性核酸酶 (DSN) 辅助靶标回收和 DNA 自组装 FeN _x C 纳米催化网络的高灵敏度和特异性电化学策略，用于精确定量 miRNA-21 作为模型。通过高温热解合成了具有高模拟过氧化物酶活性的FeN _{x C 纳米球催化剂，并用 DNA 进行了修饰。}通过精心设计的捕获探针对 miRNA-21 的识别触发了 DSN 辅助的目标回收。随后，自组装 FeN _{x通过DNA杂交反应在传感器表面构建C纳米催化网络，其信号响应被证明是单层FeN x} C的4.272倍。凭借这种级联信号放大，对miRNA-21进行超灵敏电化学检测在 0.5 fM - 1 pM 的动态范围内实现，检测限为 0.2805 fM。此外，所提出的策略对 miRNA-21 表现出高特异性和在实际样本分析中的实际适用性，证明了在疾病诊断和治疗应用中可靠的 miRNA 分析的巨大潜力。