期刊
MICROCHIMICA ACTA
卷 185, 期 10, 页码 -出版社
SPRINGER WIEN
DOI: 10.1007/s00604-018-3011-3
关键词
Enzyme mimic; Oxidase-like activity; Thymine-rich ssDNA; Colorimetric assay; Nanozyme; Visual detection; Water analysis
资金
- Natural Science Foundation of China [21765010, 21305054]
- Specialized Research Fund for the Doctoral Program of Higher Education of China [20133604120002]
This work demonstrates the inhibition effects of single-stranded (ssDNA) on the oxidase-like activity of a mixed-valence state cerium-based metal-organic framework, denoted as MVC-MOF. The MVC-MOF was synthesized by partial oxidation of cerium(III) which leads to the presence of both Ce(III) and Ce(IV) ions. The latter endows the MVC-MOF with a typical oxidase-like activity. However, on addition of ssDNA, the catalytic activity of the MVC-MOF is inhibited because it binds the MVC-MOF and thereby shield its active sites. This prevents the access of substrates. The inhibition by ssDNA depends on its length but not its sequence. By contrast, negligible changes in the oxidase-mimicking activity are observed if double-stranded DNA (dsDNA) is added. By employing a thymine-rich ssDNA (T-ssDNA) as a model DNA, a colorimetric assay was developed for the determination of Hg(II). This ion binds to T-ssDNA and causes the formation of T-dsDNA. Hence, the oxidase-mimicking activity is compromised. By using the oxidase substrate 3,3,5,5-tetramethylbenzidine that gives a colored product in the presence of oxygen, the assay has a linear response that covers 0.05 to 6M Hg(II) with a detection limit of 10.5nM, and exhibits high selectivity over other metal ions. The assay was successfully applied to the determination of Hg(II) in environmental water samples.
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