School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Nanoscale. 2017 Jun 8;9(22):7595-7601. doi: 10.1039/c6nr09500c.
Titanium dioxide nanoparticles (TiO NPs), used as pigments and photocatalysts, are ubiquitous in our daily lives. Previous work has observed cellular oxidative stress in response to the UV-excitation of photocatalytic TiO NPs. In comparison, most human exposure to TiO NPs takes place in the dark, in the lung following inhalation or in the gut following consumption of TiO NP food pigment. Our spectroscopic characterization shows that both photocatalytic and food grade TiO NPs, in the dark, generate low levels of reactive oxygen species (ROS), specifically hydroxyl radicals and superoxides. These ROS oxidize serum proteins that form a corona of proteins on the NP surface. This protein layer is the interface between the NP and the cell. An oxidized protein corona triggers an oxidative stress response, detected with PCR and western blotting. Surface modification of TiO NPs to increase or decrease surface defects correlates with ROS generation and oxidative stress, suggesting that NP surface defects, likely oxygen vacancies, are the underlying cause of TiO NP-induced oxidative stress.
二氧化钛纳米粒子（TiO2 NPs）作为颜料和光催化剂，在我们的日常生活中无处不在。先前的研究观察到细胞氧化应激是对光催化 TiO2 NPs 的紫外光激发的反应。相比之下，大多数人接触 TiO2 NPs 是在黑暗中，吸入肺部或摄入含 TiO2 NP 食品色素后进入肠道。我们的光谱表征表明，无论是光催化 TiO2 NPs 还是食品级 TiO2 NPs，在黑暗中都会产生低水平的活性氧物种（ROS），特别是羟基自由基和超氧化物。这些 ROS 会氧化血清蛋白，在 NP 表面形成一层蛋白冠。这个蛋白层是 NP 和细胞之间的界面。氧化的蛋白冠会引发氧化应激反应，这可以通过 PCR 和 Western blot 检测到。TiO2 NPs 的表面修饰增加或减少表面缺陷与 ROS 的产生和氧化应激有关，这表明 NP 表面缺陷，可能是氧空位，是 TiO2 NP 诱导氧化应激的根本原因。
