Uchino T, Tokunaga H, Ando M, Utsumi H
Division of Environmental Chemistry, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
Toxicol In Vitro. 2002 Oct;16(5):629-35. doi: 10.1016/s0887-2333(02)00041-3.
Titanium dioxide (TiO(2)) has been reported to produce OH radical under ultraviolet-A (UVA) irradiation and to induce cytotoxicity. Various crystal forms and sizes of TiO(2) with UVA irradiation from OH radical generation was analysed spin trapping-X band (electron-spin resonance (ESR) spectroscopy. The amount of OH radical was determined with ESR signal intensity of the adducts in which OH radical was trapped with the spin-trapping reagent dimethyl pyrroline-N-oxide (DMPO). The formation of OH radicals varied in both crystal size and form of TiO(2). Irradiation of the anatase form of TiO(2) produced large numbers of OH radical in TiO(2) and UVA in a dose-dependent manner, but rutil form (90 nm in size) showed less OH radical generation. The crystal size had large influence on OH radical generation, but the optimum size for the OH radical generation was different between both forms. The UVA absorption spectrum of TiO(2) differed in regard to crystal size and form of TiO(2), but no relation was observed between UVA absorbency and OH radical formation. The cytotoxicity of TiO(2)-UVA irradiation was determined against Chinese hamster ovary (CHO) cells and a significant relationship was obtained between the cytotoxicity and the OH generation. Measurement of the amount of OH radical production by UVA irradiation with ESR is needed to clarify the effect of crystal form or sizes of TiO(2) on OH radical production and cytotoxicity.
据报道，二氧化钛（TiO₂）在紫外线A（UVA）照射下会产生羟基自由基并诱导细胞毒性。通过自旋捕获-X波段（电子自旋共振（ESR）光谱）分析了具有羟基自由基生成能力的UVA照射下各种晶体形式和尺寸的TiO₂。羟基自由基的量通过自旋捕获试剂二甲基吡咯啉-N-氧化物（DMPO）捕获羟基自由基的加合物的ESR信号强度来确定。羟基自由基的形成在TiO₂的晶体尺寸和形式上均有所不同。锐钛矿型TiO₂的照射以剂量依赖的方式在TiO₂和UVA中产生大量羟基自由基，但金红石型（尺寸为90nm）显示出较少的羟基自由基生成。晶体尺寸对羟基自由基的生成有很大影响，但两种形式中羟基自由基生成的最佳尺寸不同。TiO₂的UVA吸收光谱在TiO₂的晶体尺寸和形式方面有所不同，但未观察到UVA吸光度与羟基自由基形成之间的关系。测定了TiO₂-UVA照射对中国仓鼠卵巢（CHO）细胞的细胞毒性，并且在细胞毒性与羟基自由基生成之间获得了显著关系。需要通过ESR测量UVA照射产生的羟基自由基的量，以阐明TiO₂的晶体形式或尺寸对羟基自由基产生和细胞毒性的影响。
