State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China.
Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, School of Chemical Engineering and Technology, Hainan University, Haikou 570228, P. R. China.
Anal Chem. 2022 Nov 1;94(43):15040-15047. doi: 10.1021/acs.analchem.2c03084. Epub 2022 Oct 19.
Mercury ion (Hg) is one of the most harmful heavy metal ions with the greatest impact on public health. Herein, based on the excellent catalytic activity toward 3,3',5,5'-tetramethylbenzidine (TMB) and the strong photocurrent-polarity-switching ability to SnS photoanode of the split G-quadruplex-hemin complex, the magnetic NiCoO@SiO-NH sphere-assisted colorimetric and photoelectrochemical (PEC) dual-mode sensing platform was developed for the Hg assay. First, the amino-labelled single-stranded DNA1 (S1) was immobilized on NiCoO@SiO-NH and then partly hybridized with another single-stranded DNA2 (S2). When Hg was present, the thymine-Hg-thymine base pairs between S1 and S2 were formed, causing the formation of the split G-quadruplex in the presence of K. After addition of hemin, the split G-quadruplex-hemin complex was obtained and effectually catalyzed the HO-mediated oxidation of TMB. Thus, the color and absorbance intensity of the TMB solution were changed, resulting in the visual and colorimetric detection of Hg. The linear response range is 10 pM to 10 nM, and the detection limit is 3.8 pM. Meanwhile, the above G-quadruplex-hemin complex effectively switched the photocurrent polarity of SnS-modified indium tin oxide electrode, leading to the sensitive and selective PEC assay of Hg with a linear response range of 5 pM to 500 nM and a detection limit of 2.3 pM. Moreover, the developed dual-mode sensing platform provided mutual authentication of detection results in different modes, effectively improving the assay accuracy and confidence, and may have a good potential application in highly sensitive, selective, and accurate determination of Hg in environmental fields.
汞离子 (Hg) 是对公众健康危害最大的重金属离子之一。在此，基于分裂 G-四链体-血红素配合物对 3,3',5,5'-四甲基联苯胺 (TMB) 具有优异的催化活性和对 SnS 光阳极的强光电流极性转换能力，开发了磁性 NiCoO@SiO-NH 球辅助比色和光电化学 (PEC) 双模式传感平台用于 Hg 测定。首先，将标记有氨基的单链 DNA1（S1）固定在 NiCoO@SiO-NH 上，然后与另一条单链 DNA2（S2）部分杂交。当存在 Hg 时，S1 和 S2 之间形成胸腺嘧啶-Hg-胸腺嘧啶碱基对，导致在 K 存在下形成分裂的 G-四链体。加入血红素后，得到分裂的 G-四链体-血红素配合物，有效地催化 HO 介导的 TMB 氧化。因此，TMB 溶液的颜色和吸光度强度发生变化，实现了 Hg 的可视化和比色检测。线性响应范围为 10 pM 至 10 nM，检测限为 3.8 pM。同时，上述 G-四链体-血红素配合物有效地切换了 SnS 修饰的氧化铟锡电极的光电流极性，实现了对 Hg 的灵敏和选择性 PEC 测定，线性响应范围为 5 pM 至 500 nM，检测限为 2.3 pM。此外，开发的双模式传感平台在不同模式下提供了检测结果的相互验证，有效提高了测定的准确性和可信度，并且在环境领域中对 Hg 的高灵敏度、选择性和准确测定可能具有良好的潜在应用前景。
