Characterizing the phosphatase mimetic activity of cerium oxide nanoparticles and distinguishing its active site from that for catalase mimetic activity using anionic inhibitors
Characterizing the phosphatase mimetic activity of cerium oxide nanoparticles and distinguishing its active site from that for catalase mimetic activity using anionic inhibitors
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DOI：
10.1039/c7en00394c
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发表时间：
2017-08-01
影响因子：
7.3
通讯作者：
Self, W.
中科院分区：
文献类型：
--
作者：
Dhall, A.;Burns, A.;Self, W.
氧化铈纳米颗粒(CeNPs)是一种有效的活性氧和氮氧化物清除剂，在细胞培养和动物研究中都显示出有益的抗氧化特性。然而，它们在环境中的命运，特别是在动物身上的命运，仍在调查中。研究表明，非常高剂量的CENPs可以在肝脏和骨髓等器官中短暂保留。这些纳米颗粒与其局部环境的相互作用对它们的分布和长期稳定性起着重要作用。我们先前已经证明，具有低3+/4+Ce氧化态比率的CeNPs同时具有过氧化氢酶和磷酸酶模拟活性。在这里，我们的目的是利用潜在的抑制性阴离子进一步表征参与这些催化活性的活性部位(S)。结果表明，钨酸盐和钼酸盐对磷酸酶活性无明显影响，但对过氧化氢酶活性无明显影响。这表明这两种催化活性涉及不同的化学和活性中心。此外，还观察到在水环境中CeNPs的活性更高，这强烈表明水在磷酸酶活性中起着重要作用。考虑到组织和环境中都含有丰富的磷酸盐和其他金属阴离子，研究CeNPs的催化活性及其所涉及的表面化学将有助于我们更好地理解它们的环境命运，从而限制它们在生物医学上的应用。
Cerium oxide nanoparticles (CeNPs) are potent reactive oxygen and nitrogen species scavengers and demonstrate beneficial antioxidant properties in both cell culture and animal studies. However, their environmental fate, particularly in animals, is still under investigation. Studies have shown that CeNPs at very high doses can be retained briefly in organs such as the liver and in the bone marrow. The interaction of these nanoparticles with their local environment plays a major role in their distribution and long-term stability. We have previously shown that CeNPs with a low 3+/4+ cerium oxidative state ratio exhibit both catalase and phosphatase mimetic activities. Here, we aimed at further characterizing the active site(s) involved in these catalytic activities using potentially inhibitory anions. Results indicated that tungstate and molybdate inhibited the phosphatase activity without altering the oxidative state of cerium atoms but were ineffective against catalase activity. This suggests that distinct chemistry and active sites are involved in these two catalytic activities. Additionally, it was observed that CeNPs in aqueous environments were more active, strongly suggesting that water plays an important role in the phosphatase activity. Given the abundance of phosphate and other metal anions in both tissues and the environment, studying the nature of catalytic activities of CeNPs and the surface chemistry involved will help us form a stronger understanding of their environmental fate and thus qualify their biomedical applications.