School of Chemistry and Materials Science , Jiangsu Normal University , Xuzhou 221116 , China.
Langmuir. 2018 Aug 28;34(34):10153-10162. doi: 10.1021/acs.langmuir.8b01829. Epub 2018 Aug 15.
The cytosines in cluster-nucleation sequences play a vital role in the formation of silver nanoclusters (Ag NCs). Here, an innovative electrochemiluminescence (ECL) resonance energy transfer (RET) sensing system was developed using CdS quantum dots (QDs) as ECL donor and Ag NCs as ECL acceptor. Modulation of the number of cytosines in the cluster-nucleation sequences allowed tuning of Ag NCs absorption bands to match with the ECL emission spectrum of CdS QDs, yielding effective ECL-RET. The sensitivity of detection was improved by dual-target recycling amplification based on duplex-specific nuclease (DSN) and catalytic hairpin assembly. In the presence of target microRNA-21 (miRNA-21), DSN selectively cleaved the complementary DNA section (S1), resulting in the release of the transduction section (S2) and the reuse of miRNA-21 in the next recycling amplification. Interaction of the stem-loop structure of the DNA1 segment (H1) on CdS QDs-modified electrode with S2 led to the opening of the hairpin structure of H1 and the formation of H1:S2 duplex. Then, hairpin DNA2 encapsulated Ag NCs hybridized with the remaining single-stranded DNA segment of H1, and the S2 strand was replaced. Finally, the dissociated S2 participated in subsequent reaction cycles, introducing Ag NCs to the electrode surface and leading to ECL signal quenching of the CdS QDs. The proposed sensor showed excellent performance in detecting miRNA-21 at a wide linear range from 1 fM to 100 pM. The practical application ability of the strategy was tested in HeLa cells with acceptable results, suggesting that the detection platform is a promising approach for disease diagnosis and molecular biology research.
簇核序列中的胞嘧啶在银纳米簇（Ag NCs）的形成中起着至关重要的作用。在这里，我们开发了一种创新的电化学发光（ECL）共振能量转移（RET）传感系统，该系统使用硫化镉量子点（CdS QDs）作为 ECL 供体，Ag NCs 作为 ECL 受体。通过调节簇核序列中的胞嘧啶数量，可以调节 Ag NCs 的吸收带与 CdS QDs 的 ECL 发射光谱相匹配，从而产生有效的 ECL-RET。基于双链特异性核酸酶（DSN）和催化发夹组装的双靶循环放大提高了检测的灵敏度。在靶 microRNA-21（miRNA-21）存在的情况下，DSN 选择性地切割互补的 DNA 片段（S1），导致转导片段（S2）的释放和 miRNA-21 在随后的循环放大中的再利用。与 CdS QDs 修饰电极上的 DNA1 片段（H1）的茎环结构相互作用导致 H1 的发夹结构打开，并形成 H1：S2 双链。然后，发夹 DNA2 与 H1 的剩余单链 DNA 片段杂交，并取代 S2 链。最后，解离的 S2 参与后续的反应循环，将 Ag NCs 引入电极表面，并导致 CdS QDs 的 ECL 信号猝灭。该传感器在从 1 fM 到 100 pM 的宽线性范围内对 miRNA-21 表现出优异的检测性能。该策略在 HeLa 细胞中的实际应用能力测试结果令人满意，表明该检测平台在疾病诊断和分子生物学研究方面具有广阔的应用前景。
