Protein Corona Prevents TiO2 Phototoxicity

Background & AimTiO2 nanoparticles have generally low toxicity in the in vitro systems although some toxicity is expected to originate in the TiO2-associated photo-generated radical production, which can however be modulated by the radical trapping ability of the serum proteins. To explore the role of serum proteins in the phototoxicity of the TiO2 nanoparticles we measure viability of the exposed cells depending on the nanoparticle and serum protein concentrations.Methods & ResultsFluorescence and spin trapping EPR spectroscopy reveal that the ratio between the nanoparticle and protein concentrations determines the amount of the nanoparticles’ surface which is not covered by the serum proteins and is proportional to the amount of photo-induced radicals. Phototoxicity thus becomes substantial only at the protein concentration being too low to completely coat the nanotubes’ surface.ConclusionThese results imply that TiO2 nanoparticles should be applied with ligands such as proteins when phototoxic effects are not desired - for example in cosmetics industry. On the other hand, the nanoparticles should be used in serum free medium or any other ligand free medium, when phototoxic effects are desired – as for efficient photodynamic cancer therapy.背景与研究目的 尽管二氧化钛（TiO₂）纳米颗粒在体外实验体系中通常毒性较低，但其伴随的光致自由基生成过程仍可引发一定毒性，而血清蛋白的自由基捕获能力可对该毒性起到调控作用。为探究血清蛋白在二氧化钛纳米颗粒光毒性中的作用，本研究通过检测暴露细胞的存活率，分析纳米颗粒与血清蛋白浓度对细胞存活率的影响。 方法与结果 通过荧光光谱与自旋捕获电子顺磁共振（EPR）光谱检测发现，纳米颗粒与蛋白的浓度比决定了未被血清蛋白覆盖的纳米颗粒表面占比，且该占比与光诱导自由基的生成量呈正相关。因此仅当血清蛋白浓度过低、无法完全包覆纳米管表面时，光毒性才会显著显现。 结论 上述结果表明，当无需产生光毒性效应时（如化妆品工业场景），二氧化钛纳米颗粒应与蛋白等配体共同使用。反之，当需要借助光毒性效应实现特定目标时（如高效光动力癌症治疗），则应将纳米颗粒应用于无血清培养基或其他无配体培养基中。