In this work, a surface-enhanced Raman scattering (SERS) sensing strategy was proposed for the analysis of lead ion (Pb2+) with high sensitivity and specificity based on the high specificity of the catalytic nucleic acids (DNAzymes) to Pb2+ and the catalytic hairpin assembly (CHA) amplification. First, the Pb2+-DNAzyme initiated the reaction by target Pb2+ and released a linear DNA (rS1). Second, the hairpin DNA 1 (H1) was immobilized on the SERS substrate surface via Ag-S bond. Then, the rS1 could cyclically trigger the allosteric effects of CHA amplification and the H1 was opened and then the R6G-labeled hairpin probe 2 (H2) hybridized with H1 to form H1-H2 double-stranded and the released rS1 could initiate the next cycle of CHA reaction. This process made the Raman tag of R6G close to the surface of SERS substrate, and the intensity of SERS signal from R6G labels increase with the increase of concentration of target Pb2+. Benefiting from outstanding performances of the Pb2+-specific DNAzymes and enzyme-free CHA amplification system, this biosensor exhibits good sensitivity for Pb2+ with a limit of detection of 0.42 pM. More importantly, this developed detection platform could be employed for reliable analysis of Pb2+ in real environment system.

中文翻译：

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用于基于催化发夹组件的高灵敏度和选择性 Pb2+ 检测的“信号开启”SERS 传感平台

在这项工作中，基于催化核酸 (DNAzymes) 对 Pb2+ 和催化发夹的高特异性，提出了一种表面增强拉曼散射 (SERS) 传感策略，用于分析铅离子 (Pb2+)，具有高灵敏度和特异性。组装 (CHA) 扩增。首先，Pb2+-DNAzyme 通过目标 Pb2+ 引发反应并释放线性 DNA (rS1)。其次，发夹 DNA 1 (H1) 通过 Ag-S 键固定在 SERS 基底表面。然后，rS1可以循环触发CHA扩增的变构效应，H1打开，然后R6G标记的发夹探针2（H2）与H1杂交形成H1-H2双链，释放的rS1可以启动下一个循环CHA反应。该工艺使R6G的拉曼标签贴近SERS基板表面，来自R6G标签的SERS信号强度随着目标Pb2+浓度的增加而增加。得益于 Pb2+ 特异性 DNAzymes 和无酶 CHA 扩增系统的出色性能，该生物传感器对 Pb2+ 具有良好的灵敏度，检测限为 0.42 pM。更重要的是，该开发的检测平台可用于真实环境系统中 Pb2+ 的可靠分析。