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Effect of Treatment Media on the Agglomeration of Titanium Dioxide Nanoparticles: Impact on Genotoxicity, Cellular Interaction, and Cell Cycle
Prasad, R., K. Wallace, K. Daniel, A. Tennant, R. Zucker, J. Strickland, K. Dreher, A. Kligerman, C. Blackman, AND D. DeMarini. Effect of Treatment Media on the Agglomeration of Titanium Dioxide Nanoparticles: Impact on Genotoxicity, Cellular Interaction, and Cell Cycle. ACS Nano. American Chemical Society, Washington, DC, 7(3):1929-42, (2013).
The number of consumer and commercial products containing nanoparticles already exceeds 800 and is growing at an exponential rate.1 Metal oxide nanoparticles, in particular, are currently present in the environment due to industrial processes and consumer products available on the market.2 This increased usage requires an improved understanding of the potential risks and hazards associated with human exposure. Specifically, it is critically important to identify those physicochemical characteristics of nanoparticles that may cause detrimental health effects.
ABSTRACT The widespread use of titanium dioxide (TiO2) nanoparticles in consumer products increases the probability of exposure to humans and the environment. Although TiO2 nanoparticles have been shown to induce DNA damage (comet assay) and chromosome damage (micronucleus assay, MN) in vitro, no study has systematically assessed the influence of medium composition on the physicochemical characteristics and genotoxicity of TiO2 nanoparticles. We assessed TiO2 nanoparticle agglomeration, cellular uptake, influence on cell cycle, and induction of genotoxicity in human lung epithelial cells using three different nanoparticle-treatment media: supplemented keratinocyte growth medium (KGMTM) medium plus 0.1% bovine serum albumin (KB), a synthetic broncheoalveolar lavage fluid containing PBS and 0.06% bovine serum albumin and 0.001% surfactant (DM), or supplemented KGMTM with 10% fetal bovine serum (KF). The comet assay showed that TiO2 nanoparticles induced DNA damage in all 3 media. These results indicate that DNA damage occurred regardless of the amount of agglomeration measured by dynamic-light scattering or cellular uptake and cell-cycle changes measured by flow cytometry. However, TiO2 nanoparticles induced MN only in KF, which is the medium that facilitated the lowest amount of agglomeration, the greatest amount of nanoparticle cellular uptake, and the highest population of cells accumulating in S phase. These results with TiO2 nanoparticles in KF demonstrate an association between particle uptake and nanoparticle interaction with cells that leads to chromosomal damage as measured by the MN assay. KEYWORDS Titanium dioxide nanoparticles, genotoxicity, micronuclei, comet assay, DNA damage, flow cytometry, cell cycle, dark-field microscopy, electron microscopy