Dodd Nicholas J F, Jha Awadhesh N
School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK.
Mutat Res. 2009 Jan 15;660(1-2):79-82. doi: 10.1016/j.mrfmmm.2008.10.007. Epub 2008 Nov 1.
Titanium dioxide (TiO(2)) nanoparticles have been shown to be genotoxic to cells exposed to ultraviolet A (UVA) radiation. Using the technique of electron spin resonance (ESR) spin trapping, we have confirmed that the primary damaging species produced on irradiation of TiO(2) nanoparticles is the hydroxyl (OH) radical. We have applied this technique to TiO(2)-treated fish and mammalian cells under in vitro conditions and observed the additional formation of carboxyl radical anions (CO(2)(-)) and superoxide radical anions (O(2)(-)). This novel finding suggests a hitherto unreported pathway for damage, involving primary generation of OH radicals in the cytoplasm, which react to give CO(2)(-) radicals. The latter may then react with cellular oxygen to form O(2)(-) and genotoxic hydrogen peroxide (H(2)O(2)).
二氧化钛（TiO₂）纳米颗粒已被证明对暴露于紫外线A（UVA）辐射的细胞具有遗传毒性。利用电子自旋共振（ESR）自旋捕获技术，我们证实了TiO₂纳米颗粒辐照产生的主要损伤物种是羟基（OH）自由基。我们已将该技术应用于体外条件下经TiO₂处理的鱼类和哺乳动物细胞，并观察到羧基自由基阴离子（CO₂⁻）和超氧自由基阴离子（O₂⁻）的额外形成。这一新发现表明了一条迄今未报道的损伤途径，涉及细胞质中OH自由基的初级生成，这些自由基反应生成CO₂⁻自由基。后者随后可能与细胞内的氧气反应形成O₂⁻和具有遗传毒性的过氧化氢（H₂O₂）。
