College of Biological Sciences and Engineering, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Institute of Nanomedicine and Nanobiosensing, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350116, China.
Analyst. 2018 Apr 30;143(9):2122-2127. doi: 10.1039/c8an00462e.
A simple, fast, sensitive, and homogeneous electrochemical sensor based on the T-Hg2+-T structure and exonuclease III-assisted recycling amplification has been constructed for mercury ion (Hg2+) detection. The cT and methylene blue-labeled DNA probes (MB-TDNA) were designed to contain poly T sequences, which were repulsed from the negatively charged indium tin oxide (ITO) electrode due to their abundant negative charges. Hg2+ could trigger the formation of double-stranded DNA (dsDNA) between two DNA probes owing to the stable T-Hg2+-T structure. Then, Exo III specifically recognizes the cleavage of the double-stranded structure to release a methylene blue-labeled mononucleotide fragment (MB-MF). Moreover, the release of the target Hg2+ induces new hybridization and produces a large number of MB-MFs; MB-MFs are not repulsed by the negatively charged ITO electrode surface, thus producing a significant current signal. Under optimal conditions, the differential pulse voltammetric (DPV) response had a linear relationship with the logarithm of Hg2+ concentration in the range of 1.0 nM-0.5 μM, and the proposed method displayed great applicability for detecting Hg2+ in tap-water samples.
基于 T-Hg2+-T 结构和外切酶 III 辅助循环放大作用，构建了一种用于汞离子 (Hg2+) 检测的简单、快速、灵敏、均相电化学传感器。设计了 cT 和亚甲基蓝标记的 DNA 探针 (MB-TDNA)，它们含有丰富的负电荷，由于其丰富的负电荷，被排斥在带负电荷的氧化铟锡 (ITO) 电极之外。由于稳定的 T-Hg2+-T 结构，Hg2+可以触发两个 DNA 探针之间的双链 DNA (dsDNA) 的形成。然后，外切酶 III 特异性识别双链结构的切割，释放出一个亚甲基蓝标记的单核苷酸片段 (MB-MF)。此外，目标 Hg2+ 的释放诱导新的杂交，并产生大量的 MB-MFs；MB-MFs 不受带负电荷的 ITO 电极表面的排斥，因此产生显著的电流信号。在最佳条件下，差分脉冲伏安法 (DPV) 响应与 Hg2+浓度的对数在 1.0 nM-0.5 μM 范围内呈线性关系，该方法在检测自来水中的 Hg2+方面表现出很好的适用性。
