Iron-rich single walled carbon nanotubes are effective catalysts of oxidative stress in RAW 264.7 macrophage cell culture model: interactions with inflammatory response and in vivo implications.
Kagan V; Potapovich A; Osipov A; Schwegler-Berry D; Kisin E; Mercer R; Castranova V; Shvedova A
Free Radic Biol Med 2004 Jan; 37(Suppl 1):S51-S52
Single walled carbon nanotubes (SWCNT) are new emerging materials. Their manufacturing includes catalysis on iron particles. SWCNT induced inflammation provides a redox milieu in which iron can synergistically enhance damage to cells/tissue. RAW 264.7 macrophages were used to characterize the cell ability to respond to iron-rich/deplete SWCNT. EPR spectroscopy found that iron-rich (but not iron-deplete) SWCNT displayed a broad signal with g value 2.0 and half-width of 640G attributable to high spin Fe+3. Co-incubation of macrophages with SWCNT resulted in their engulfment detectable by TEM. Depletion of GSH and slightly increased number of apoptotic cells in response to SWCNT was observed. No intracellular production of superoxide or NO was triggered by SWCNT as evidenced by flow cytometry with DHE and DAF-2-DA, respectively. EPR spin-trapping demonstrated that iron-rich (but not iron-deplete) SWCNT were redox-active and converted superoxide radicals produced by zymosan-stimulated marophages into hydroxyl radicals. Similarly, superoxide extracellularly generated by xanthine oxidase/xanthine yielded hydroxyl radicals. Iron-rich SWCNT oxidized ascorbate to its radical. These in vitro results are in line with marked inflammatory response and early onset of fibrotic changes in the lungs of C57BL/6 mice exposed to SWCNT.
Iron-compounds; Oxidative-processes; Stress; Cell-cultures; Models; In-vivo-studies; Nanotechnology
Free Radical Biology and Medicine