Antioxidant Properties of Cerium Oxide Nanocrystals as a Function of Nanocrystal Diameter and Surface Coating
Antioxidant Properties of Cerium Oxide Nanocrystals as a Function of Nanocrystal Diameter and Surface Coating
复制标题
DOI：
10.1021/nn4026806
复制
发表时间：
2013-11-01
期刊：
影响因子：
17.1
通讯作者：
Colvin, Vicki L.
中科院分区：
文献类型：
--
作者：
Lee, Seung Soo;Song, Wensi;Colvin, Vicki L.
本研究考察了纳米晶体直径和表面涂层对氧化铈纳米晶体在化学溶液和细胞中与H2O2反应性的影响。在有机溶剂中，铈前驱体分解形成单分散的纳米晶体，随后以两亲体作为纳米颗粒涂层相转移到水中。采用气相色谱法和鲁米诺测试对CeO2-x的抗氧化能力进行了定量分析，结果表明，每摩尔铈（III）与2 mol H2O2反应，表明反应是通过fenton型机制进行的。较小直径的纳米晶含有较多的铈（III），对H2O2的反应性更强。此外，表面涂层的存在并没有阻止纳米晶体表面铈（III）和过氧化氢之间的反应。总的来说，反应性最强的纳米颗粒是最小的（例如直径3.8 nm），表面涂层最薄（例如油酸）。此外，对其抗氧化能力的基准测试显示，这些材料的反应性是商业抗氧化剂（如Trolox）的9倍。这些抗氧化剂纳米晶体的一个独特之处在于它们可以多次应用：几周后，富含铈（IV）的颗粒慢慢恢复到初始的铈（III）含量。在几乎所有的情况下，颗粒保持胶体稳定（例如，不聚集），可以作为抗氧化剂多次应用。在细胞培养中也观察到这些化学性质，其中材料能够减少暴露于H2O2的人真皮成纤维细胞的氧化应激，其效率与其溶液反应性相当。这些数据表明，氧化铈纳米晶体上的有机涂层不会限制纳米晶体的抗氧化行为，并且即使在稳定的情况下，它们的氧化还原还原行为也可以保持。
This work examines the effect of nanocrystal diameter and surface coating on the reactivity of cerium oxide nanocrystals with H2O2 both in chemical solutions and in cells. Monodisperse nanocrystals were formed in organic solvents from the decomposition of cerium precursors, and subsequently phase transferred into water using amphiphiles as nanoparticle coatings. Quantitative analysis of the antioxidant capacity of CeO2-x using gas chromatography and a luminol test revealed that 2 mol of H2O2 reacted with every mole of cerium(III), suggesting that the reaction proceeds via a Fenton-type mechanism. Smaller diameter nanocrystals containing more cerium(III) were found to be more reactive toward H2O2. Additionally, the presence of a surface coating did not preclude the reaction between the nanocrystal surface cerium(III) and hydrogen peroxide. Taken together, the most reactive nanoparticles were the smallest (e.g., 3.8 nm diameter) with the thinnest surface coating (e.g., oleic acid). Moreover, a benchmark test of their antioxidant capacity revealed these materials were 9 times more reactive than commercial antioxidants such as Trolox. A unique feature of these antioxidant nanocrystals is that they can be applied multiple times: over weeks, cerium(IV) rich particles slowly return to their starting cerium(III) content. In nearly all cases, the particles remain colloidally stable (e.g., nonaggregated) and could be applied multiple times as antioxidants. These chemical properties were also observed in cell culture, where the materials were able to reduce oxidative stress in human dermal fibroblasts exposed to H2O2 with efficiency comparable to their solution phase reactivity. These data suggest that organic coatings on cerium oxide nanocrystals do not limit the antioxidant behavior of the nanocrystals, and that their redox cyding behavior can be preserved even when stabilized.