Nano-cerium dioxide (CeO2) possesses the potential for use in human health by protecting against the deleterious effects of ischemia and radiation. However, the literature is polarized about the effects this compound has in vivo. Our laboratory has shown that pulmonary nano-CeO2 impairs arteriolar reactivity 24 hrs post-exposure. The mechanisms of this impairment are currently unknown but may be linked to the free radical scavenging or inflammatory properties of this nanoparticle. The aims of this study were to: 1) thoroughly assess the physical and chemical characteristics of the nano-CeO2, 2) examine the antioxidant potential of nano-CeO2 via electron spin resonance (ESR), and 3) assess the pulmonary inflammation in Sprague-Dawley rats 24 hrs post-intratracheal nano-CeO2 instillation. The primary particle size of the nano-CeO2 was calculated to ~3 nm (via transmission electron microscopy and surface area measurements). Dynamic light scattering determined the agglomerate size (~80 nm) and x-ray photoelectron spectroscopy determined the valence state of the nano-CeO2. The ESR measurements indicated that nano-CeO2 alone did not generate free radicals and in the presence of cells (Raw264.7), nano-CeO2 quenched the free radicals generated by these cells. Finally, bronchial alveolar lavage from rats instilled with 0, 10, 100 or 400 microg of nano-CeO2 revealed an increase in polymorphonuclear leukocytes (0.6±0.2, 0.8±0.3, 7.1±0.9, and 10.3±0.9 per 106 cells), and lactate dehydrogenase (90±12, 100±9, 453±33, and 602±32 units/L) but there was no change in albumin. These findings provide evidence that pulmonary inflammation is present after exposure but does not damage to the epithelial/endothelial cellular barrier. Additionally, these nanoparticles are capable of quenching free radicals there by exerting a systemic effect.
Toxicology; Nanotechnology; Laboratory-animals; Exposure-levels; Pulmonary-system; Dose-response; Lung-irritants; Cerium-compounds; Dioxides; In-vivo-study; Free-radicals; Free-radical-generation; Immune-reaction; Chemical-properties; Physical-properties; Antioxidants; Electrochemical-properties; Lung-cells; Alveolar-cells; Leukocytes; Cell-function; Cellular-reactions
The Toxicologist. Society of Toxicology 52nd Annual Meeting and ToxExpo, San Antonio, Texas, March 10-14, 2013