Crystalline Phase Modulates the Potency of Nanometric TiO2 to Adhere to and Perturb the Stratum Corneum of Porcine Skin under Indoor Light

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• 作者：Francesco Turci ; Elena Peira ; Ingrid Corazzari ; Ivana Fenoglio ; Michele Trotta ; Bice Fubini
• 刊名：Chemical Research in Toxicology
• 出版年：2013
• 出版时间：October 21, 2013
• 年：2013
• 卷：26
• 期：10
• 页码：1579-1590
• 全文大小：567K
• 年卷期：v.26,no.10(October 21, 2013)
• ISSN：1520-5010

文摘

Nanometric TiO₂ is largely employed in cosmetics, but in vitro toxic effects have been reported when nano-TiO₂ is exposed to UV light. The photoreactivity of TiO₂ largely depends on its crystal phase, namely, anatase and rutile. Surface acidity, which is also dependent on crystal structure, may impart a positive or negative charge to the nanomaterial surface and ultimately modulate particle adhesion to tissues. Three nanometric TiO₂ powders with a different crystal lattice and surface charge (anatase, rutile, and anatase/rutile) have been employed here to investigate their interaction with the skin and to examine the molecular mechanisms of the TiO₂-induced oxidative damage. The strength of the interaction of nano-TiO₂ with skin has been revealed by chemiometric mapping (渭-XRF and SEM鈥揈DS) after tissue washing. Positively charged anatase and anatase/rutile, but not negatively charged rutile, were strongly held on the skin surface and were able to promote a structural rearrangement of the lipid bilayer in the stratum corneum (DSC and Raman) under controlled indoor illumination (UVA < 1 mW/m²). Under the same conditions, cell-free reactivity tests (ROS-mediated free-radical release and lipoperoxidation) indicated that anatase and anatase/rutile are more reactive than rutile, suggesting a ROS-mediated oxidative mechanism that may alter the structure of the stratum corneum. Both the higher oxidative potential and the stronger adhesion to skin of anatase and anatase/rutile TiO₂ may explain the stronger disorganization induced by these two samples and suggests the use of rutile to produce safer TiO₂-based cosmetic and pharmaceutical products.