Abstract A simple protease-free and signal-on electrochemical biosensor based on GR-5 DNAzyme and catalytic hairpin assembly (CHA) for sensitive lead ion (Pb2+) assay was constructed in this work. In the presence of Pb2+, GR-5 DNAzyme specifically reacted with Pb2+ and cleaved the substrate strand into two free DNA fragments, and one of the two fragments then opened the hairpin capture DNA (Hc) that was assembled on the Au electrode surface and triggered the CHA reaction. Exploiting the CHA strategy, a large number of the hairpin signal DNA (Hs) labeled with two methylene blues (Mbs) were captured on the Au electrode surface and generated an efficient electron transfer, resulting in the dramatic increase of methylene blue current. In this method, Pb2+ could be detected quantitatively in the range of 4 × 10−11–3 × 10−6 M, and the detection limit was as low as 2.7 × 10−11 M (S/N = 3). Experimental results demonstrated that the biosensor was highly specific for Pb2+ and exhibited remarkable improvements of electrochemical analytical performance. This biosensor was also used for the analysis of Pb2+ in the serum sample spiked with Pb2+, and the obtained result in good agreement with the correct values. The excellent performance of the biosensor shows its promising potential for the clinical diagnosis of lead poisoning.

中文翻译：

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基于 GR-5 DNAzyme 和催化发夹组装的无蛋白酶和信号电化学生物传感器用于超灵敏检测铅离子

摘要 本工作构建了一种基于GR-5 DNAzyme 和催化发夹组装(CHA) 的简单无蛋白酶和信号电化学生物传感器，用于敏感铅离子(Pb2+) 测定。在 Pb2+ 存在下，GR-5 DNAzyme 特异性地与 Pb2+ 反应并将底物链切割成两个游离 DNA 片段，然后两个片段之一打开组装在 Au 电极表面并触发的发夹捕获 DNA (Hc) CHA反应。利用CHA策略，大量用两种亚甲蓝（Mbs）标记的发夹信号DNA（Hs）被捕获在Au电极表面并产生有效的电子转移，导致亚甲蓝电流急剧增加。该方法可在 4 × 10−11–3 × 10−6 M 范围内定量检测 Pb2+，检测限低至 2.7 × 10−11 M (S/N = 3)。实验结果表明，该生物传感器对 Pb2+ 具有高度特异性，并显示出电化学分析性能的显着改善。该生物传感器还用于分析加标 Pb2+ 的血清样品中的 Pb2+，所得结果与正确值吻合良好。该生物传感器的优异性能显示出其在铅中毒临床诊断方面的潜力。并且得到的结果与正确的值非常吻合。该生物传感器的优异性能显示出其在铅中毒临床诊断方面的潜力。并且得到的结果与正确的值非常吻合。该生物传感器的优异性能显示出其在铅中毒临床诊断方面的潜力。