Health Impacts of Carbon Nanomaterials: Role of IronResidues in Cellular Toxicity and DNA Damage

摘要

Many varieties of c carbon nanotubes and nanofibers contain nanophase iron as arbon a residue of the growth catalyst. Itis believed that redox redox-active surface iron plays an important role in asbestos toxicity by generating reactive oxygenspecies in vivo that damage DNA. There is a critical need to establish whether the same mechanism occurs foriron iron-containing carbon nanomaterials. Commercial carbon nanotubes and nanofibers are complex materialscontaining a variety of carbon forms and variable amounts of metal that may be wholly or partially encapsulatedby carbon. Here we study the mechanisms of iron mediated toxicity using simple model carbons with well well-definedcomposition and structure. Highly Highly-pure and uniform uniform-sized carbon nanofibers are produced from liquid phasetemplating, and are contacted in vitro with mouse mouse-derived macrophages. For a direct measure of iron effects, thesame tests are carried out on the pure fibers doped with highly highly-accesssible nanophase surface iron. The biologicalendpoints include cell proliferation, cell death, cytokine expression (TNF TNF-alpha), and plasmid DNA single strandbreaks. The same tests are carried out raw and iron iron-doped carbon black and non non-toxic titanium dioxi dioxide asde reference materials. Preliminary results of this well well-controlled mechani mechanistic stud stic study suggest y that nanophase iron, if bioaccessible, can result in DNA damage, cell death, and cytokine expression. Ongoing work focuses oncommercial nanotube samples where issues of iron encapusulation and bioavailability add additional complexity.