title: Effects of nitrogen-doped multi-walled carbon nanotubes compared to pristine multi-walled carbon nanotubes on human small airway epithelial cells.
abstract: Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose-response cell proliferation assay showed that low doses of ND-MWCNT (1.2μg/ml) or MWCNT-7 (0.12μg/ml) increased cellular proliferation, while the highest dose of 120μg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6h and were internalized by 24h. ROS were elevated at 6 and 24h in ND-MWCNT exposed cells, but only at 6h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2μg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects.
authors: Pharmaceutical and Pharmacological Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26505, United States; Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Amy L
authors: AL
authors: Mihalchik
authors: Shared Research Facilities, West Virginia University, Morgantown, WV 26505, United States.
authors: Weiqiang
authors: W
authors: Ding
authors: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Dale W
authors: DW
authors: Porter
authors: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Colleen
authors: C
authors: McLoughlin
authors: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Diane
authors: D
authors: Schwegler-Berry
authors: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Jennifer D
authors: JD
authors: Sisler
authors: Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Aleksandr B
authors: AB
authors: Stefaniak
authors: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States.
authors: Brandi N
authors: BN
authors: Snyder-Talkington
authors: Research Center for Exotic Nanocarbons, Shinshu University, Nagano, Japan.
authors: Rodolfo
authors: R
authors: Cruz-Silva
authors: Research Center for Exotic Nanocarbons, Shinshu University, Nagano, Japan; Departments of Physics, Chemistry, Materials Science & Engineering, and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, United States.
authors: Mauricio
authors: M
authors: Terrones
authors: Research Center for Exotic Nanocarbons, Shinshu University, Nagano, Japan.
authors: Shuji
authors: S
authors: Tsuruoka
authors: Research Center for Exotic Nanocarbons, Shinshu University, Nagano, Japan.
authors: Morinobu
authors: M
authors: Endo
authors: Pharmaceutical and Pharmacological Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26505, United States.
authors: Vincent
authors: V
authors: Castranova
authors: Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, United States. Electronic address: yaq2@cdc.gov.
authors: Yong
authors: Y
authors: Qian
mesh_terms: D055745:Bronchioles / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D037742:Nanotubes, Carbon / Q000633:toxicity*; D009584:Nitrogen / Q000378:metabolism / Q000633:toxicity*; D010769:Phosphothreonine / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D056951:Photoelectron Spectroscopy; D017382:Reactive Oxygen Species / Q000378:metabolism; D018570:Risk Assessment; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D018675:Toxicity Tests / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D037742:Nanotubes, Carbon; D017382:Reactive Oxygen Species; D010769:Phosphothreonine; D019000:Phosphotyrosine; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4; D009584:Nitrogen
keywords: Functionalized multi-walled carbon nanotubes; Multi-walled carbon nanotubes; Reactive oxygen species