Oxidative interactions of single walled carbon nanotubes with RAW 264.7 macrophages: role of iron.
Shvedova-AA; Potapovich-AI; Osipov-AN; Tyurina-YY; Kisin-E; Schwegler-Berry-D; Mercer-R; Castranova-V; Kagan-VE
Toxicologist 2006 Mar; 90(1):318
Single-walled carbon nanotubes (SWCNT) have unique physico-chemical properties and may exhibit unusual interactions with cells, thus necessitating studies of their toxicity. Manufactured SWCNT usually contain significant amounts of iron that may act as a catalyst of oxidative stress. Because macrophages are the primary responders to different particles that initiate and propagate inflammatory reactions and oxidative stress, we utilized two types of SWCNT: 1) iron-rich (non-purified) SWCNT (26 weight% of iron) and 2) iron-stripped (purified) SWCNT (0.23 weight% of iron) to study their interactions with RAW 264.7 macrophages. Ultrasonication resulted in predominantly well-dispersed and separated SWCNT strands as evidenced by scanning electron microscopy. Neither purified nor nonpurifed SWCNT were able to generate intracellular production of superoxide radicals or nitric oxide in RAW 264.7 macrophages as documented by flow cytometry. SWCNT with different iron content displayed different redox activity in a cell-free model system as revealed by EPR-detectable formation of ascorbate radicals. Co-incubation of zymosan-stimulated RAW 264.7 macrophages with non-purifed ironrich SWCNT generated more hydroxyl radicals (documented by EPR spin-trapping with 5,5-dimethyl-1-pyrroline-N-oxide, DMPO) than with purified SWCNT. Similarly, in the presence of zymosan-stimulated RAW 264.7 macrophages, non-purified SWCNT more effectively converted superoxide radicals generated by xanthine oxidase/xanthine into hydroxyl radicals as compared to purified SWCNT. Iron-rich SWCNT caused significant loss of intracellular GSH and accumulation of lipid hydroperoxides in zymosan-stimulated RAW 264.7 macrophages. Thus, iron in SWCNT may be important in determining redox-dependent responses of macrophages.
Iron-compounds; Models; Oxidative-processes; Oxidation; Toxins; Nanotechnology
Disease and Injury: Asthma and Chronic Obstructive Pulmonary Disease
The Toxicologist. Society of Toxicology 45th Annual Meeting and ToxExpo, March 5-9, 2006, San Diego, California
University of Pittsburgh at Pittsburgh