College of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China.
School of Water Conservancy and Environment, University of Jinan, Jinan 250022, P. R. China.
Analyst. 2019 Jun 21;144(12):3836-3842. doi: 10.1039/c9an00508k. Epub 2019 May 16.
A rapid and label-free fluorescence biosensing strategy for highly sensitive detection of microRNA-122 (miR-122) has been developed by the combination of DNA three-way junction (TWJ)-actuated strand displacement and a fluorescence light-up Ag nanocluster (AgNC) probe. In the presence of target miR-122, the attachment of miR-122 to its complementary DNA results in the unblocking of the toehold and branch migration domains in the TWJ, activating the strand displacement reaction (SDR) accompanied by the proximity between the G-rich DNA probe and DNA-AgNC probe; thus a remarkably enhanced fluorescence signal of AgNCs can be obtained owing to the G-rich fluorescence enhancement mechanism. The results reveal that this biosensor exhibits superb specificity and high sensitivity toward miR-122 with a detection limit of 0.030 nM. In addition, the practicality of the biosensor is demonstrated by analyzing miR-122 in three cell lines with satisfactory results. Furthermore, by the utilization of the toehold-mediated SDR and DNA-AgNC conjugates, this proposed strategy offers the advantages of rapidness, convenience, low cost, and simplified operation without the need for biological labeling and the addition of enzymes. Thus, the constructed biosensor might provide a valuable and practical tool for detecting miRNA and the related clinical diagnosis and fundamental biomedicine research.
一种快速且无需标记的荧光生物传感策略，通过 DNA 三链体（TWJ）触发的链置换和荧光点亮的银纳米簇（AgNC）探针的结合，实现了对 microRNA-122（miR-122）的高灵敏度检测。在存在靶标 miR-122 的情况下，miR-122 与互补 DNA 的结合导致 TWJ 中的结合域和分支迁移域解锁，激活链置换反应（SDR），同时伴随着富含 G 的 DNA 探针和 DNA-AgNC 探针之间的接近；因此，由于富含 G 的荧光增强机制，可以获得 AgNCs 的显著增强的荧光信号。结果表明，该生物传感器对 miR-122 表现出优异的特异性和高灵敏度，检测限低至 0.030 nM。此外，通过在三种细胞系中分析 miR-122，证明了该生物传感器的实用性，结果令人满意。此外，通过利用引发链置换的 TWJ 和 DNA-AgNC 缀合物，该策略具有快速、方便、低成本和简化操作的优点，无需生物标记和酶的添加。因此，所构建的生物传感器可能为检测 miRNA 及其相关临床诊断和基础生物医学研究提供有价值的实用工具。
