Fenton activity and cytotoxicity studies of iron-loaded carbon particles

The chemical and biological properties of iron-loaded manufactured carbon nanoparticles (Flammruss 101) were contrasted with those of an iron-loaded synthetic carbon particle. X-ray photoelectron spectroscopy was used to characterize the iron on the carbon particles. Production of hydroxyl free radicals via the Fenton reaction was monitored by electron paramagnetic resonance spectroscopy. The iron-loaded synthetic carbon particles produced a positive Fenton response, whereas the iron-loaded manufactured carbon particles did not. The source of the Fenton activity of the synthetic carbon particles is proposed to be a soluble iron compound that was formed during the synthesis of the particle. A likely candidate for the soluble iron species is Fe2F5, which was synthesized and its properties were examined. Higher toxicity of Fe2F5 toward murine macrophages compared with other simple iron salts was attributed to soluble iron that was stabilized by the fluoride ligand. The cytotoxicity of manufactured carbon particles toward murine macrophages decreased or remained unaltered upon impregnation with iron compounds.