Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China; College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan, Zigong 643000, PR China.
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Biosens Bioelectron. 2015 Jun 15;68:266-271. doi: 10.1016/j.bios.2015.01.010. Epub 2015 Jan 3.
This work reported a label-free colorimetric assay for sensitive detection of Hg(2+) based on Hg(2+)-triggered hairpin DNA probe (H-DNA) termini-binding and exonuclease Ш (Exo Ш)-assisted target recycling, as well as hemin/G-quadruplex (DNAzyme) signal amplification. The specific binding of free Hg(2+) with the thymine-thymine (T-T) mismatches termini of H-DNA could immediately trigger the Exo Ш digestion, and then set free G-quadruplex segments and Hg(2+). The Exo Ш impellent recycling of ultratrace Hg(2+) produced numerous G-quadruplexes. The corresponding DNAzymes catalyzed efficiently the H2O2-mediated oxidation of the ABTS(2-) to the colored product in the presence of hemin. Using the color change as the output signal, and the Exo Ш-aided Hg(2+) recycling and DNAzyme as the signal amplifier, the ultrasensitive assay system successfully achieved visual detection of Hg(2+) as low as 1.0 nM by the naked eye, and was suitable for field monitoring. The calibration curve was linear in the range of 50.0 pM to 20.0 nM for Hg(2+) (R=0.9962) with a detection limit of 10.0 pM. Moreover, this proposed strategy showed excellent selectivity, portability and low-cost, and was successfully applied to colorimetric detection of Hg(2+) in laboratory tap water and Jialing river water samples.
本工作报道了一种基于汞离子（Hg(2+)）触发发夹 DNA 探针（H-DNA）末端结合和外切酶Ш（Exo Ш）辅助目标循环以及血红素/G-四链体（DNAzyme）信号放大的用于灵敏检测 Hg(2+)的无标记比色分析方法。游离 Hg(2+)与 H-DNA 的胸腺嘧啶-胸腺嘧啶（T-T）错配末端的特异性结合可立即触发 Exo Ш 消化，随后释放 G-四链体片段和 Hg(2+)。超痕量 Hg(2+)的 Exo Ш 推动的循环可产生大量 G-四链体。相应的 DNAzyme 在血红素存在下可有效地催化 H2O2 介导的 ABTS(2-)的氧化为有色产物。利用颜色变化作为输出信号，以及 Exo Ш 辅助的 Hg(2+)循环和 DNAzyme 作为信号放大器，该超灵敏分析系统成功地实现了对 Hg(2+)的肉眼可见检测，检测限低至 1.0 nM。此外，该方法具有线性范围宽（50.0 pM 至 20.0 nM，R=0.9962），检测限低（10.0 pM），选择性好，便携性和低成本，并且成功地应用于实验室自来水和嘉陵江河水样品中 Hg(2+)的比色检测。
