Over the last decade, metal oxide nanoparticles have been widely used in biomedical applications such as sunscreens, toothpastes, and even food products. There has been a growing concern over the toxicity of these metal oxide nanoparticles as they interact with the living cells, and other intracellular parts at the nanoscale. Studies examining 4th-period transition metal oxide nanoparticles (20 to 60 nm in diameter) using human bronchial epithelial cells shows a trend in toxicity that roughly corresponds with transition metal periodicity. We have investigated a variety of factors that govern these observed trends. Point-of-zero charge (PZC), metal oxide dissolution, and the degree of surface hydroxylation on the nanoparticle surfaces were studied. Nanoparticles were placed in a constant composition reactor (16 hours) to maintain pH conditions and mimic physiological conditions at pH = 7.4. Surface hydroxylation was studied by comparing integrated peak area ratios of hydroxyl versus metal oxide oxygen using X-ray photoelectron spectroscopy (XPS) O 1s core levels. The PZC of these nanoparticles largely match observed PZC trends: Mn2O3 > ZnO = CuO > NiO > CoO > Fe2O3 > Cr2O3 > TiO2. In addition to analysis of PZC and degree of surface hydroxylation, effects of nanoparticle dissolution, BET surface area and the interplay of these physicochemical  properties that govern the degree of cytoxicity were probed.

Correlation of metal oxide nanoparticle physicochemical properties with cytotoxicity

242nd National Meeting (2011)

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