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The retina as a potential site of nanomaterial phototoxicity
Citation:
BOYES, W. K. The retina as a potential site of nanomaterial phototoxicity. Presented at International Neurotoxicology Association Meeting, Xian, CHINA, June 06 - 10, 2011.
Impact/Purpose:
Photo-catalytic reactions can generate reactive oxygen species (ROS) and precipitate toxic reactions in tissues exposed to light, such as the retina.
Description:
Manufactured nanomaterials are designed for their unique properties, one of which is to be photoreactive. Photocatalysts are desirable in many applications including self-cleaning surfaces, sterilization and decontamination of polluted media, and photovoltaic devices. Photo-catalytic reactions can generate reactive oxygen species (ROS) and precipitate toxic reactions in tissues exposed to light, such as the retina. Nano-titanium dioxide (Ti0 2) catalyzes reactions under UV radiation and was hypothesized to cause phototoxicity. A human-derived line of retinal pigment epithelial cells (ARPE-19) was treated with samples of nano-Tio, that varied in primary particle size and crystal structure, and exposed to either darkness or to UVA radiation. Viability was assessed after 24 hrs by microscopy using a live/dead assay (calcein-AM/propidium iodide) or by flow cytometry. Cells exposed to Ti02 along with UVA showed a dose-related decrease of viability, and the degree of response varied by Ti02 size and crystalline structure. Under UVA radiation, the relative toxicity of the Ti02 samples correlated with reactivity, particle size, and surface area. These experiments demonstrate that Ti02 nanoparticles become phototoxic when exposed to UVA radiation, with potency related to the inter-dependent properties of reactivity, size, and surface area. The views expressed in this abstract are those of the author and do not represent the policy of the US EPA