School for Radiological and Interdisciplinary Sciences (RAD-X), Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.
Division of Bioanalytical Chemistry and Division of Analytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
ACS Nano. 2016 Nov 22;10(11):10436-10445. doi: 10.1021/acsnano.6b06297. Epub 2016 Nov 9.
To develop nanomaterials as artificial enzymes, it is necessary to better understand how their physicochemical properties affect their enzyme-like activities. Although prior research has demonstrated that nanomaterials exhibit tunable enzyme-like activities depending on their size, structure, and composition, few studies have examined the effect of surface facets, which determine surface energy or surface reactivity. Here, we use electron spin-resonance spectroscopy to report that lower surface energy {111}-faceted Pd octahedrons have greater intrinsic antioxidant enzyme-like activity than higher surface energy {100}-faceted Pd nanocubes. Our in vitro experiments found that those same Pd octahedrons are more effective than Pd nanocubes at scavenging reactive oxygen species (ROS). Those reductions in ROS preserve the homogeneity of mitochondrial membrane potential and attenuate damage to important biomolecules, thereby allowing a substantially higher number of cells to survive oxidative challenges. Our computations of molecular mechanisms for the antioxidant activities of {111}- and {100}-faceted Pd nanocrystals, as well as their activity order, agree well with experimental observations. These findings can guide the design of antioxidant-mimicking nanomaterials, which could have therapeutic or preventative potential against oxidative stress related diseases.
为了将纳米材料开发为人工酶，有必要更好地了解它们的物理化学性质如何影响其类似酶的活性。尽管先前的研究已经表明，纳米材料的酶样活性可以根据其尺寸、结构和组成进行调节，但很少有研究探讨表面各向异性对表面能或表面反应性的影响。在这里，我们使用电子自旋共振谱来报告，具有较低表面能的{111}面 Pd 八面体比具有较高表面能的{100}面 Pd 纳米立方体具有更大的内在抗氧化酶样活性。我们的体外实验发现，这些相同的 Pd 八面体在清除活性氧物种（ROS）方面比 Pd 纳米立方体更有效。这些 ROS 的减少保持了线粒体膜电位的均一性，并减轻了对重要生物分子的损伤，从而使更多的细胞能够在氧化应激下存活。我们对{111}和{100}面 Pd 纳米晶体抗氧化活性的分子机制的计算，以及它们的活性顺序，与实验观察结果非常吻合。这些发现可以指导抗氧化模拟纳米材料的设计，这些纳米材料可能具有治疗或预防与氧化应激相关疾病的潜力。
