title: A highly sensitive protocol for the determination of Hg(2+) in environmental water using time-gated mode.
abstract: In this paper, a sensitive time-gated fluorescent sensing strategy for mercury ions (Hg(2+)) monitoring is developed based on Hg(2+)-mediated thymine (T)-Hg(2+)-T structure and the mechanism of fluorescence resonance energy transfer from Mn-doped CdS/ZnS quantum dots to graphene oxide. The authors employ two T-rich single-stranded DNA (ssDNA) as the capture probes for Hg(2+), and one of them is modified with Mn-doped CdS/ZnS quantum dots. The addition of Hg(2+) makes the two T-rich ssDNA hybrids with each other to form stable T-Hg(2+)-T coordination chemistry, which makes Mn-doped CdS/ZnS quantum dots far away from the surface of graphene oxide. As a result, the fluorescence signal is increased obviously compared with that without Hg(2+). The time-gated fluorescence intensities are linear with the concentrations of Hg(2+) in the range from 0.20 to 10 nM with a limit of detection of 0.11 nM. The detection limit is much lower than the U.S. Environmental Protection Agency limit of the concentration of Hg(2+) for drinking water. The time-gated fluorescent sensing strategy is specific for Hg(2+) even with interference by other metal ions based on the results of selectivity experiments. Importantly, the proposed sensing strategy is applied successfully to the determination of Hg(2+) in environmental water samples.
authors.affiliation: College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Hunan University, Changsha 410082, China; South China Institute of Environmental Sciences, Ministry of Environmental Protection of PRC, Guangzhou 510655, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Hunan University, Changsha 410082, China. Electronic address: cgniu@hnu.edu.cn.
authors.forename: Chenggang
authors.initials: C
authors.lastname: Niu
authors.affiliation: College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Hunan University, Changsha 410082, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
authors.affiliation: College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Hunan University, Changsha 410082, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Hunan University, Changsha 410082, China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Lv
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D002413:Cations, Divalent; D004277:DNA, Single-Stranded / Q000138:chemical synthesis / Q000737:chemistry; D060766:Drinking Water / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005618:Fresh Water / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis*; D010087:Oxides; D045663:Quantum Dots / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D013941:Thymine / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D002413:Cations, Divalent; D004277:DNA, Single-Stranded; D060766:Drinking Water; D010087:Oxides; D018036:Selenium Compounds; D013440:Sulfides; D014874:Water Pollutants, Chemical; D017967:Zinc Compounds; D006108:Graphite; C058667:cadmium selenide; D008628:Mercury; C031238:zinc sulfide; D013941:Thymine
keywords: Graphene oxide; Hg(2+); Mn:CdS/ZnS quantum dots; Thymine–Hg(2+)–thymine; Time-gated fluorescent sensing strategy