Citation:

Ortenzio, J., L. Degn, R. Zucker, J. Virkutyte, S. Al-Abed, H. Ma, S. Diamond, K. Dreher, AND W. Boyes. Potential phototoxicity of aged Al(OH)3-coated Ti02 nanoparticles in retinal pigment epithelial cells. Presented at Society of Toxicology, March 10 - 14, 2013.

Impact/Purpose:

This abstract will be presented at the Society of Toxicology meeting, March 10-14, 2013, San Antonio, TX

Description:

Titanium dioxide (TiO2) nanoparticles (NPs) exposed to UVA radiation generate reactive oxygen species (ROS). As a component of sunscreen formulations, TiO2 NPs may be coated with Al(OH)3 to prevent ROS from causing oxidative damage to tissues. Simulated swimming pool water (SSPW) degrades the Al(OH)3 coating which could reduce the coating’s protective function. We examined the potential phototoxicity of 25 nm, Al(OH)3-TiO2 NPs that had been aged in SSPW for 0 min, 45 min, 1 day, 3 days, 10 days, or 14 days. In two non cellular assays, measuring methylene blue degredation or thiobarbituric acid reactive species, aged Al(OH)3-TiO2 showed substantially less photocatalytic activity than the positive control: uncoated Aeroxide P25, 31 nm. In a cellular assay, a human-derived retinal pigment epithelium cell line (ARPE-19) was used as a site of photoreactivity. Cells were split into 24-well culture plates, incubated for 24h, then treated with 0, 3, 10, 30, or 100 ug/ml of each aged NP or 30 ug/ml of positive control. After treatment, the cells were either exposed to 1.5h UVA radiation or no light. 24h later, cell viability was assessed by live/dead assays (calcein-AM/propidium iodide). Flow cytometry and dark field microscopy verified that the TiO2 NPs entered the cells. Flow cytometry showed dose‐related increased side‐scatter signal consistent with uptake of NPs, and dark field microscopy showed TiO2 accumulation along the nuclear envelope and near the endoplasmic reticulum of ARPE‐19 cells. No difference in cytotoxicity was observed after UVA irradiance among the SSPW-aged groups. The positive control yielded 100% cytotoxicity under UVA irradiation. The lack of phototoxicity observed with SSPW-aged Al(OH)3-TiO2 suggests that degradation of the particle coating did not increase the risk of phototoxic reactions under the conditions tested. This abstract does not reflect EPA policy.

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