Sun Kai, Liu Qingzhu, Zhu Rui, Liu Qi, Li Shunyao, Si Youbin, Huang Qingguo
Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036 Anhui, China.
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Int J Anal Chem. 2019 Nov 3;2019:5416963. doi: 10.1155/2019/5416963. eCollection 2019.
Certain nano-scale metal oxides exhibiting the intrinsic enzyme-like reactivity had been used for environment monitoring. Herein, we evaluated the oxidase-mimicking activity of environmentally relevant nano-MnO and its sensitivity to the presence of metal ions, and particularly, the use of MnO nanozyme to potentially detect Cu, Zn, Mn, and Fe in water. The results indicated the oxidase-like activity of nano-MnO at acidic pH-driven oxidation of 2,6-dimethoxyphenol (2,6-DMP) via a single-electron transfer process, leading to the formation of a yellow product. Notably, the presence of Cu and Mn heightened the oxidase-mimicking activity of nano-MnO at 25°C and pH 3.8, showing that Cu and Mn could modify the reactive sites of nano-MnO surface to ameliorate its catalytic activity, while the activity of MnO nanozyme in systems with Zn and Fe was impeded probably because of the strong affinity of Zn and Fe toward nano-MnO surface. Based on these effects, we designed a procedure to use MnO nanozyme to, respectively, detect Cu, Zn, Mn, and Fe in the real water samples. MnO nanozyme-based detecting systems achieved high accuracy (relative errors: 2.2-26.1%) and recovery (93.0-124.0%) for detection of the four metal ions, respectively. Such cost-effective detecting systems may provide a potential application for quantitative determination of metal ions in real water environmental samples.
某些具有内在类酶活性的纳米级金属氧化物已被用于环境监测。在此，我们评估了与环境相关的纳米MnO的模拟氧化酶活性及其对金属离子存在的敏感性，特别是利用MnO纳米酶潜在检测水中的铜、锌、锰和铁。结果表明，纳米MnO在酸性pH条件下通过单电子转移过程驱动2,6 - 二甲氧基苯酚（2,6 - DMP）氧化，呈现出类氧化酶活性，导致形成黄色产物。值得注意的是，铜和锰的存在提高了纳米MnO在25°C和pH 3.8时的模拟氧化酶活性，表明铜和锰可以修饰纳米MnO表面的反应位点以改善其催化活性，而在含有锌和铁的体系中MnO纳米酶的活性受到阻碍，这可能是由于锌和铁对纳米MnO表面具有很强的亲和力。基于这些效应，我们设计了一种程序，利用MnO纳米酶分别检测实际水样中的铜、锌、锰和铁。基于MnO纳米酶的检测系统对四种金属离子的检测分别实现了高精度（相对误差：2.2 - 26.1%）和高回收率（93.0 - 124.0%）。这种具有成本效益的检测系统可能为实际水环境样品中金属离子的定量测定提供潜在应用。
