Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo , Waterloo, Ontario Canada , N2L 3G1.
Anal Chem. 2016 Apr 5;88(7):4014-20. doi: 10.1021/acs.analchem.6b00327. Epub 2016 Mar 24.
Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis.
银是一种非常常见的重金属，对其进行检测具有重要的分析意义。脱氧核酶是基于 DNA 的催化剂；它们通常招募二价和三价金属离子进行催化。在此，我们报道了一种经过六轮体外选择得到的银特异性 RNA 切割 DNA 酶，命名为 Ag10c。Ag10c 在 pH 7.5 时，在 200 mM NaNO3 中以 10 μM Ag(+)的浓度显示出 0.41 min(-1)的催化速率，而相同浓度的 NaCl 则完全抑制其活性。Ag10c 在所有测试的金属中对 Ag(+)具有高度特异性。通过在 DNA 酶上标记荧光团和淬灭剂，设计了催化信标生物传感器。在存在 Ag(+)的情况下观察到荧光增强，检测限为 24.9 nM Ag(+)。该传感器在休伦湖水中表现出相似的分析性能。这是第一个依赖单价过渡金属的 RNA 切割 DNA 酶。除了其生物传感器应用外，本研究还加强了探索超越传统多价离子依赖 DNA 酶催化理解的想法。
