Citation:

Green, TeresaD, A. El-Badawy, T. Tolaymat, AND D. Thomas. Comparative Cytotoxicity of Silver Nanomaterials in a Murine Macrophage Cell Line. Presented at Society of Toxicology, March 10 - 14, 2013.

Impact/Purpose:

This abstract describes the effect of ionic silver and silver nanomaterials on the viability of a murine macrophage cell line. Similarities in potency of ionic silver and nanosilver as a cytotoxicant in this cell line suggests similarities in the kinetic behavior of the element in these cells.

Description:

Manufactured silver nanomaterials (AgNPs) are used as antimicrobials in many consumer products. Although increased use of AgNPs increases risk of exposure through inhalation or ingestion, there are few data on human health risks associated with exposure to these materials. Here, we have evaluated the toxicity of AgNPs in the murine macrophage J774A.1 cell line. Macrophages play an important role in the inflammatory response by phagocytosis of pathogens, cellular debris, and foreign particles. Phagocytosis of AgNPs by macrophages could expose these cells to Ag and alter cell structure and function. We used two in vitro cytotoxicity assays, lactate dehydrogenase (LDH) release and the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) to compare cytotoxic effects of ionic Ag (Ag nitrate), polyvinylpyrrolidone PVP coated-AgNPs (MHD =13 nm), hydrogen reduced H2-AgNPs (14 nm), and citrate AgNPs (12 nm). Cells were exposed to ionic Ag, PVP-coated AgNPs, H2-AgNPs, or citrate-AgNPs, either in media alone or in media supplemented with 1% fetal bovine serum (FBS), for 1, 4, or 24 hours before assessment of cellular status. Each AgNP diminished MTT reduction capacity of J774A.1 cells with 50% reductions in activity seen in the low parts per million of Ag concentration range. Compared with AgNPs, ionic Ag, was a more potent cytotoxin. LDH leakage increased after exposure to ionic Ag and AgNPs indicated that all compounds produced damage to cell membranes. In MTT assays, addition of 1% FBS to media mitigated the cytotoxic effects of all forms of Ag. In LDH assays, the addition of FBS did not affect Ag-dependent membrane damage. These results indicate AgNPs affect the integrity of cell membranes and the metabolic competency of cells, although it is yet unclear whether these effects are mediated through phagocytosis of AgNPs or by accumulation of Ag solubilized from nanoparticles. Future in vitro and in vivo studies that examine the disposition, fate, and effects of AgNPs will provide more information for assessment of the bioavailability and potential human health risks of these materials. (This abstract does not reflect U.S. EPA policy.)

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