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An evaluation of the influence of size and radiation in silver nanoparticle toxicity
Citation:
HUTCHINSON, S. L., L. DEGN, R. M. ZUCKER, AND W. K. BOYES. An evaluation of the influence of size and radiation in silver nanoparticle toxicity. Presented at 3rd Annual Conference on the Environmental Implications of Nanotechnology (ICEIN), Durham, NC, May 09 - 11, 2011.
Impact/Purpose:
Because the retina is the only part of the nervous system that is exposed to light and because other nanoparticles have been determined to be phototoxlc, human retinal pigment epithelial cells (ARPE-19) were· used to test the phototoxicity of PVP-coated silver nanoparticles (Ag-PVP NP).
Description:
The antimicrobial properties of silver nanoparticles (AgNP) have made them popular in textile manufacturing, medical technology, and biomedical applications. Studies suggest that after ingestion, nanomaterials are distributed throughout the body to different organs, possibly including the eyes. Furthermore, some nanomaterials, including silver, have been developed into drug delivery systems that can be administered to the eye directly. Because the retina is the only part of the nervous system that is exposed to light and because other nanoparticles have been determined to be phototoxlc, human retinal pigment epithelial cells (ARPE-19) were· used to test the phototoxicity of PVP-coated silver nanoparticles (Ag-PVP NP). Nanoparticles were suspended in cell culture medium with fetal bovine serum (FBS) and dosing suspensions were characterized using dynamic light scattering (Malvern Zetasizer Nano). ARPE-19 cells were grown to confluence in DMEM/F12 + 10% FBS and dosed with 0, 3, 10, 30, 55, 100, & 200 ug/ml of 10, 50, and 75nm Ag-PVP (nanoComposix). Twenty-four hours after dosing, the cells were exposed to three light conditions (UV light, visible light, or no light exposure) for two hours. Forty-eight hours after the initial application of silver, a live/dead assay (Calcein AM/propidium iodide) was used to measure cell viability. Additionally, flow cytometry and dark field microscopy were used to measure cytotoxicity and to verify that the AgNP entered the cells. Flow cytometry confirmed that cells dosed with 75nm AgNP-PVP were more viable than those dosed with either 50nm or 10nm AgNP-PVP. The data within each size consistently suggested that nano-silver toxicity increased in a dose dependent manner, and was inversely proportional to particle size. Analysis of variance followed by a Tukey HSD test indicated no difference between the viabilities of AgNP-treated cells left in the dark and those exposed to visible light. However, cells from both of these exposure treatments were significantly (p<0.05) more viable than cells exposed to AgNP and UV light. Additional post hoc LSMEANS testing revealed a significant effect of UV radiation for the 75nm AgNP-PVP, but not for the 50nm or 10nm AgNP-PVP. However, the phototoxicity of the 75nm AgNP-PVP was not consistent over all test replicates. Visible light did not influence AgNP toxicity, and there was no apparent increase in the toxicity of 10 or 50 nm particles by UV irradiation. However, the potential UV phototoxicity of 75 nm AgNP-PVP remains unclear. This abstract does not reflect EPA policy.