title: Biodegradation of single-walled carbon nanotubes by eosinophil peroxidase.
abstract: Eosinophil peroxidase (EPO) is one of the major oxidant-producing enzymes during inflammatory states in the human lung. The degradation of single-walled carbon nanotubes (SWCNTs) upon incubation with human EPO and H₂O₂ is reported. Biodegradation of SWCNTs is higher in the presence of NaBr, but neither EPO alone nor H₂O₂ alone caused the degradation of nanotubes. Molecular modeling reveals two binding sites for SWCNTs on EPO, one located at the proximal side (same side as the catalytic site) and the other on the distal side of EPO. The oxidized groups on SWCNTs in both cases are stabilized by electrostatic interactions with positively charged residues. Biodegradation of SWCNTs can also be executed in an ex vivo culture system using primary murine eosinophils stimulated to undergo degranulation. Biodegradation is proven by a range of methods including transmission electron microscopy, UV-visible-NIR spectroscopy, Raman spectroscopy, and confocal Raman imaging. Thus, human EPO (in vitro) and ex vivo activated eosinophils mediate biodegradation of SWCNTs: an observation that is relevant to pulmonary responses to these materials.
authors: Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Nobels Väg 13, Stockholm 17177, Sweden.
authors: Fernando T
authors: FT
authors: Andón
authors: Alexandr A
authors: AA
authors: Kapralov
authors: Naveena
authors: N
authors: Yanamala
authors: Weihong
authors: W
authors: Feng
authors: Arjang
authors: A
authors: Baygan
authors: Benedict J
authors: BJ
authors: Chambers
authors: Kjell
authors: K
authors: Hultenby
authors: Fei
authors: F
authors: Ye
authors: Muhammet S
authors: MS
authors: Toprak
authors: Birgit D
authors: BD
authors: Brandner
authors: Andrea
authors: A
authors: Fornara
authors: Judith
authors: J
authors: Klein-Seetharaman
authors: Gregg P
authors: GP
authors: Kotchey
authors: Alexander
authors: A
authors: Star
authors: Anna A
authors: AA
authors: Shvedova
authors: Bengt
authors: B
authors: Fadeel
authors: Valerian E
authors: VE
authors: Kagan
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D047209:Eosinophil Peroxidase / Q000378:metabolism; D004804:Eosinophils / Q000378:metabolism; D006801:Humans; D051379:Mice; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D047209:Eosinophil Peroxidase
keywords: biodegradable materials; carbon nanotubes; eosinophil peroxidase; molecular modeling