In this work, we present a multiple amplified electrochemical method that can detect target microRNA‐21 (miRNA‐21) with high sensitivity by using hierarchical flower‐like gold nanostructures (HFGNs) and gold‐enriched enzyme‐free amplification. The HFGNs deposited on ITO conducting glass served as the electrode substrate with large specific surface area, which allowed the immobilization of large amounts of capture DNA (DNA‐1). Then, the gold‐enriched hybridization chain reaction (HCR) for signal amplification was attached onto the electrode through target miRNA‐mediated sandwich hybridization. The initial strands (I‐DNA) enriched on gold nanoparticles (AuNPs) provided plenty of sites for the triggering of the HCR reaction after the addition of H1 and H2 strands, which provided exponential increase of binding sites for the loading of electrochemical signal molecules [Ru(NH₃)₆]³⁺. Therefore, multiple signal amplification could be achieved to reach an ultrasensitive detection of miRNA‐21. A wide linear dynamic range from 1 fM to 1 nM and a detection limit of 0.12 fM (S/N=3) was reached with good selectivity. The electrochemical assay method in this work may hold a great potential for clinical diagnosis of genetic disease in the future.

中文翻译：

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多层花状金纳米结构结合富金杂交链反应对MicroRNA-21的多重扩增电化学检测

在这项工作中，我们提出了一种多重扩增电化学方法，该方法可以通过使用分层的类花状金纳米结构（HFGNs）和富含金的无酶扩增方法，以高灵敏度检测目标microRNA-21（miRNA-21）。沉积在ITO导电玻璃上的HFGN用作具有大比表面积的电极基材，从而可以固定大量捕获DNA（DNA-1）。然后，通过靶标miRNA介导的夹心杂交将用于信号放大的富金杂交链反应（HCR）连接到电极上。添加H1和H2链后，富集于金纳米颗粒（AuNPs）上的初始链（I-DNA）为触发HCR反应提供了大量位点，₃）₆ ] ³⁺。因此，可以实现多重信号放大，以实现miRNA-21的超灵敏检测。线性动态范围从1 fM到1 nM，检测极限为0.12 fM（S / N = 3），具有良好的选择性。这项工作中的电化学测定方法可能在将来对遗传疾病的临床诊断具有巨大的潜力。