Abstract：
Robust and sensitive methods for the detection of microRNAs (miRNAs) are crucial in the clinical diagnosis of cancers. In this study, a novel electrochemical biosensor with high sensitivity for miRNA-21 detection is developed, which relies on the formation of a peptide nucleic acid (PNA)-DNA hetero-three-way junction (H3WJ) and target-recycling catalytic hairpin assembly (CHA) amplification. The electroneutral PNA probes are initially immobilized onto a gold electrode to construct the sensor. Upon introduction of miRNA-21, target-recycling CHA is initiated, resulting in abundant double-stranded CHA products. Subsequently, association between the PNA probes and these products leads to the formation of PNA-DNA H3WJs. Consequently, the electrode surface is densely populated with numerous electroactive Ferrocene (Fc) groups, resulting in a significantly amplified current response for highly sensitive detection of miRNA-21 at concentrations as low as 0.15 fM. This approach demonstrates remarkable specificity towards target miRNAs and can be utilized for quantitative monitoring of miRNA-21 expression in human cancer cells. More importantly, the sensor exhibits exceptional stability and shows a significant reduction in background noise during miRNA detection, making this method a highly promising sensing platform for monitoring various miRNA biomarkers to facilitate the diagnosis of diverse cancers.
摘要：
检测microRNAs（miRNAs）的稳健和灵敏的方法在癌症的临床诊断中至关重要。在这项研究中,开发了一种用于miRNA-21检测的高灵敏度电化学生物传感器，其依赖于肽核酸(PNA)-DNA异源三通连接(H3WJ)的形成和靶再循环催化发夹组装(CHA)扩增。电中性PNA探针最初固定在金电极上以构建传感器。在引入miRNA-21后，启动靶向再循环CHA，导致丰富的双链CHA产品。随后，PNA探针和这些产物之间的缔合导致PNA-DNAH3WJ的形成。因此,电极表面密集地填充有许多电活性二茂铁(Fc)基团，导致在低至0.15fM的浓度下高灵敏度检测miRNA-21的显著放大的电流响应。这种方法证明了对靶miRNA的显著特异性，可用于定量监测人癌细胞中miRNA-21的表达。更重要的是,该传感器表现出优异的稳定性，并在miRNA检测过程中显示出背景噪声的显着降低，使这种方法成为监测各种miRNA生物标志物以促进多种癌症诊断的非常有前途的传感平台。
