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Titanium Dioxide (P25) Produces Reactive Oxygen Species in Immortalized Brain Microglia (BV2): Implications for Nanoparticle Neurotoxicity

Long, T.C. and Saleh, Navid and Tilton, Robert D. and Lowry, Gregory V. and Veronesi, Bellina (2006) Titanium Dioxide (P25) Produces Reactive Oxygen Species in Immortalized Brain Microglia (BV2): Implications for Nanoparticle Neurotoxicity. Environmental Science & Technology, 40 (14). pp. 4346-4352. ISSN 0013936X

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Official URL: http://dx.doi.org/10.1021/es060589n

Abstract

Concerns with the environmental and health risk of widely distributed, commonly used nanoparticles are increasing. Nanosize titanium dioxide (TiO2) is used in air and water remediation and in numerous products designed for direct human use and consumption. Its effectiveness in deactivating pollutants and killing microorganisms relates to photoactivation and the resulting free radical activity. This property, coupled with its multiple potential exposure routes, indicates that nanosize TiO2 could pose a risk to biological targets that are sensitive to oxidative stress damage (e.g., brain). In this study, brain microglia (BV2) were exposed to a physicochemically characterized (i.e., dispersion stability, particle size distribution, and zeta potential) nanomaterial, Degussa P25, and cellular expressions of reactive oxygen species were measured with fluorescent probes. P25's zeta potentials, measured in cell culture media and physiological buffer were −11.6 ± 1.2 mV and −9.25 ± 0.73 mV, respectively. P25 aggregation was rapid in both media and buffer with the hydrodynamic diameter of stable P25 aggregates ranging from 826 nm to 2368 nm depending on the concentration. The biological response of BV2 microglia to noncytotoxic (2.5−120 ppm) concentrations of P25 was a rapid (<5 min) and sustained (120 min) release of reactive oxygen species. The time course of this release suggested that P25 not only stimulated the immediate “oxidative burst” response in microglia but also interfered with mitochondrial energy production. Transmission electron microscopy indicated that small groups of nanosized particles and micron-sized aggregates were engulfed by the microglia and sequestered as intracytoplasmic aggregates after 6 and 18 h exposure to P25 (2.5 ppm). Cell viability was maintained at all test concentrations (2.5−120 ppm) over the 18 h exposure period. These data indicate that mouse microglia respond to Degussa P25 with cellular and morphological expressions of free radical formation.

Item Type:Article
Subjects:Biomedical Science > Nanoscale biological processes
Biomedical Science > Nanotechnology for human health
NanoSafety > Environment, health and safety aspects of nanotechnology
ID Code:35
Deposited By:Lesley Tobin
Deposited On:22 Oct 2008 14:53
Last Modified:22 Jan 2009 13:43

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