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Generation of reactive oxygen species by silicon nanowires.

Chapman-RS; Roberts-JR; Castranova-V; Leonard-SS
Toxicologist 2009 Mar; 108(1):184
Silicon nanowires (NW) are anisotropic crystals with semi-conductor capabilities and are currently being utilized in the production of biosensors, gas sensors, and field electric transistors. Because of their composition and large length to diameter ratio, silicon NW-induced toxicity may differ from other forms of nanoparticles. A variety of different forms of nanoparticles have been shown to produce toxic effects in cellular and animal models through the induction of oxidative stress. The potential for oxidative damage after exposure to silicon NW has not been investigated. The goal of this study was to assess the generation of free radicals by silicon NW. Electron spin resonance (ESR) was used to monitor hydroxyl radical production in an acellular system by measuring Fenton-like reactions in the presence of hydrogen peroxide. In addition, the ability to produce radicals after cellular exposure was also determined by ESR. These measures of particle surface reactivity of silicon NW (20 nm diameter x 10 mu m length) at two different concentrations (0.2 mg/ml or 0.1mg/ml), were compared to those of titanium dioxide (TiO2) NW (0.1 mg/ml or 0.05 mg/ml), amosite asbestos fibers (0.2 mg/ml or 0.1 mg/ml), and lead chromate particles (PbCrO4) as a positive control (0.5 mg/ml). For in vitro studies, two cell types were used to measure reactive oxygen species (ROS) production, primary rat macrophages harvested from the lungs of male Sprague-Dawley rats and the RAW 264.7 macrophage cell line. ESR results showed no presence of hydroxyl radical or ROS production with silicon NW, in either the acellular or cellular systems. Hydroxyl radicals were observed in PbCrO4 and amosite asbestos. However, radicals were not seen in TiO2 NW. These findings indicate that silicon NW may not induce a significant increase in oxidative stress and associated damage.
Absorption-rates; Asbestos-fibers; Biological-effects; Biological-factors; Chemical-hypersensitivity; Chemical-reactions; Cell-metabolism; Cellular-reactions; Exposure-assessment; Exposure-levels; Exposure-methods; Molecular-biology; Laboratory-animals; Lung; Lung-cells; Lung-tissue; Oxidative-metabolism; Oxidative-processes; Respiratory-irritants; Statistical-analysis; Nanotechnology
7440-21-3; 7440-32-6; 13463-67-7; 7439-92-1
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The Toxicologist. Society of Toxicology 48th Annual Meeting and ToxExpo, March 15-19, 2009, Baltimore, Maryland