ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology , 08860 Castelldefels, Barcelona, Spain.
The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States.
J Phys Chem B. 2017 Sep 21;121(37):8619-8625. doi: 10.1021/acs.jpcb.7b04208. Epub 2017 Sep 11.
Titanium dioxide (TiO) nanoparticles, used as pigments and photocatalysts, are widely present in modern society. Inhalation or ingestion of these nanoparticles can lead to cellular-level interactions. We examined the very first step in this cellular interaction, the effect of TiO nanoparticles on the lipids of the plasma membrane. Within 12 h of TiO nanoparticle exposure, the lipids of the plasma membrane were oxidized, determined with a malondialdehyde assay. Lipid peroxidation was inhibited by surface passivation of the TiO nanoparticles, incubation with an antioxidant (Trolox), and the presence of serum proteins in solution. Subsequent experiments determined that serum proteins adsorbed on the surface of the TiO nanoparticles, forming a protein corona, inhibit lipid peroxidation. Super-resolution fluorescence microscopy showed that these serum proteins were clustered on the nanoparticle surface. These protein clusters slow lipid peroxidation, but by 24 h, the level of lipid peroxidation is similar, independent of the protein corona or free serum proteins. Additionally, over 24 h, this corona of proteins was displaced from the nanoparticle surface by free proteins in solution. Overall, these experiments provide the first mechanistic investigation of plasma membrane oxidation by TiO nanoparticles, in the absence of UV light and as a function of the protein corona, approximating a physiological environment.
二氧化钛（TiO）纳米粒子，用作颜料和光催化剂，广泛存在于现代社会中。这些纳米粒子的吸入或摄入可能会导致细胞水平的相互作用。我们研究了这种细胞相互作用的第一步，即 TiO 纳米粒子对质膜脂质的影响。在暴露于 TiO 纳米粒子 12 小时内，通过丙二醛测定法确定质膜的脂质发生了氧化。通过 TiO 纳米粒子的表面钝化、与抗氧化剂（Trolox）孵育以及溶液中存在血清蛋白，抑制了脂质过氧化。随后的实验确定，吸附在 TiO 纳米粒子表面的血清蛋白形成了一个蛋白质冠，从而抑制了脂质过氧化。超分辨率荧光显微镜显示，这些血清蛋白在纳米粒子表面聚集。这些蛋白质簇减缓了脂质过氧化，但 24 小时后，脂质过氧化的水平相似，与蛋白质冠或游离血清蛋白无关。此外，在 24 小时以上的时间内，溶液中的游离蛋白将这些蛋白质的冠从纳米粒子表面置换出来。总的来说，这些实验首次对 TiO 纳米粒子在没有紫外线的情况下并作为蛋白质冠的功能对质膜氧化进行了机制研究，接近生理环境。
