Horie Masanori, Sugino Sakiko, Kato Haruhisa, Tabei Yosuke, Nakamura Ayako, Yoshida Yasukazu
a Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Takamatsu , Kagawa , Japan ;
b National Metrology Institute of Japan, AIST , Tsukuba , Ibaraki , Japan.
Toxicol Mech Methods. 2016 May;26(4):284-94. doi: 10.1080/15376516.2016.1175530. Epub 2016 May 4.
Titanium dioxide (TiO2) nanoparticles are important industrial nano-objects with wide applications, including as photocatalysts and sunscreen components. Recently, the phototoxicity of TiO2 nanoparticles has been a concern. However, phototoxicity caused by photocatalytic activity may differ between anatase and rutile nanoparticles. In the present study, we compared the phototoxicity of anatase and rutile nanoparticles. Human keratinocyte HaCaT cells were treated with stable TiO2 nanoparticle suspensions. Without UVA irradiation, TiO2 nanoparticles did not affect mitochondrial activity or cell membranes. However, exposure to rutile nanoparticle suspensions inhibited cell growth and induced HO-1 gene expression without UVA irradiation. These effects may be explained by the hydrophobic surface of rutile nanoparticles. Next, TiO2-exposed cells were irradiated with UVA for 4 h and effects of TiO2 nanoparticles on cells were examined. The rutile nanoparticles did not show any cellular effects after UVA irradiation. However, the anatase nanoparticles caused strong phototoxicity. Decreased mitochondrial activity, cell membrane damage and the induction of oxidative stress were observed in the cells exposed to anatase nanoparticles with UVA irradiation. Cellular uptake of the nanoparticles was observed in both anatase- and rutile-exposed cells. These results suggest that internalized anatase nanoparticles are important for phototoxicity. Additionally, the exposure of a 3D skin model to TiO2 nanoparticles did not result in significant toxicity. In conclusion, rutile nanoparticles used in sunscreen did not exhibit phototoxic activity. Despite the strong phototoxic activity of anatase nanoparticles in cell cultures, they demonstrated no phototoxicity using a 3D skin model.
二氧化钛（TiO₂）纳米颗粒是重要的工业纳米材料，具有广泛应用，包括作为光催化剂和防晒成分。最近，TiO₂纳米颗粒的光毒性受到关注。然而，锐钛矿型和金红石型纳米颗粒由光催化活性引起的光毒性可能有所不同。在本研究中，我们比较了锐钛矿型和金红石型纳米颗粒的光毒性。用稳定的TiO₂纳米颗粒悬浮液处理人角质形成细胞HaCaT细胞。在没有UVA照射的情况下，TiO₂纳米颗粒不影响线粒体活性或细胞膜。然而，在没有UVA照射的情况下，暴露于金红石型纳米颗粒悬浮液会抑制细胞生长并诱导HO-1基因表达。这些效应可能由金红石型纳米颗粒的疏水表面来解释。接下来，用UVA照射TiO₂处理过的细胞4小时，并检查TiO₂纳米颗粒对细胞的影响。UVA照射后，金红石型纳米颗粒未显示任何细胞效应。然而，锐钛矿型纳米颗粒引起强烈的光毒性。在暴露于UVA照射的锐钛矿型纳米颗粒的细胞中观察到线粒体活性降低、细胞膜损伤和氧化应激诱导。在暴露于锐钛矿型和金红石型纳米颗粒的细胞中均观察到纳米颗粒的细胞摄取。这些结果表明内化的锐钛矿型纳米颗粒对光毒性很重要。此外，将三维皮肤模型暴露于TiO₂纳米颗粒不会导致明显的毒性。总之，用于防晒霜的金红石型纳米颗粒未表现出光毒性活性。尽管锐钛矿型纳米颗粒在细胞培养中具有强烈的光毒性活性，但在三维皮肤模型中它们未显示出光毒性。
