title: Biodegradation of Single-Walled Carbon Nanotubes in Macrophages through Respiratory Burst Modulation.
abstract: The biodegradation of carbon nanotubes (CNTs) may be one of major determinants of the toxic outcomes in exposed individuals. In this study, we employed a macrophage/monocyte model, Raw264.7, to investigate the feasibility of regulating the biodegradation of three types of single-walled carbon nanotubes (SWCNTs) (pristine, ox-, and OH-SWCNTs) by respiratory burst modulation. An artificial fluid mimicking the enzymatic reactions of respiratory burst was constituted to reveal the role of respiratory burst played in SWCNT biodegradation. The biodegradation of SWCNTs were characterized by Raman, ultraviolet-visible-near-infrared spectroscopy, and transmission electron microscopy. Our results showed significantly accelerated biodegradation of ox-SWCNTs and OH-SWCNTs in macrophages activated by phorbol myristate acetate (PMA), which could be prevented by N-acetyl-l-cysteine (NAC), whereas p-SWCNTs were resistant to biodegradation. Similar tendencies were observed by using the in vitro enzymatic system, and the degradation rates of these SWCNTs are in the order of OH-SWCNTs > ox-SWCNTs >> p-SWCNTs, suggesting a pivotal role of respiratory burst in accelerating the biodegradation of SWCNTs and that defect sites on SWCNTs might be a prerequisite for the biodegradation to occur. Our findings might provide invaluable clues on the development of intervention measurements for relieving the side effects of SWCNTs and would help to design safer SWCNT products with higher biodegradability and less toxicity.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. jiehou_st@rcees.ac.cn.
authors.forename: Jie
authors.initials: J
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. binwan@rcees.ac.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Wan
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. yuyang@rcees.ac.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. xmren@rcees.ac.cn.
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. LHGuo@rcees.ac.cn.|Institute of Environment and Health, Jianghan University, Wuhan 430056, China. LHGuo@rcees.ac.cn.
authors.forename: Liang-Hong
authors.initials: LH
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. jfliu@rcees.ac.cn.
authors.forename: Jing-Fu
authors.initials: JF
authors.lastname: Liu
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002460:Cell Line; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D037742:Nanotubes, Carbon; D016897:Respiratory Burst
chemical_list: D000975:Antioxidants; D037742:Nanotubes, Carbon
keywords: biodegradation; in vitro enzymatic system; respiratory burst; single-walled carbon nanotubes