title: [Effect of functionalized multi-walled carbon nanotubes on L02 cells].
abstract: OBJECTIVE
  To investigate the cytotoxic effect of multi-walled carbon nanotubes (MWCNTs) on human liver L02 cells and its relevant mechanism.
  
  
  METHODS
  MWCNTs, carboxyl modification MWCNTs (MWCNTs-COOH), and hydroxyl modification MWCNTs (MWCNTs-OH) were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The carbon nanotubes at concentrations of 12.5, 25, 50, 100, and 200 μg/ml were incubated with human liver L02 cells for 24, 48 and 72 hours, respectively. The cell viability was evaluated by water soluble tetrazolium salts assay and the intercellular reactive oxygen species induced by the carbon nanotubes were detected by 2', 7'-dichlorodihydrofluorescein diacetate method.
  
  
  RESULTS
  Transmission electron microscope showed that the average outside diameters (10 to 20 nm) and the average length (10 to 30 μm) of the three MWCNTs were similar. Scanning electron microscope indicated that the three MWCNTs had a similar surface topography. X-ray photoelectron spectroscopy demonstrated that the MWCNTs-COOH and MWCNTs-OH had relatively high peak areas at 289 and 286ev, respectively,indicating that they have been modified by carboxyl and hydroxyl groups,respectively. Water soluble tetrazolium salts assay showed that the MWCNTs-COOH was less cytotoxic when compared to MWCNTs which demonstrated to be slightly more cytotoxic than MWCNTs-OH. The capability to induce increase in intracellular reactive oxygen species was in the following order: MWCNTs > MWCNTs-COOH > MWCNTs-OH.
  
  
  CONCLUSIONS
  Modification of MWCNTs with carboxyl group and hydroxyl group improves the biocompatibility of MWCNTs to some extents. MWCNTs-COOH has better compatibility than MWCNTs at the low concentration,and MWCNTs-OH showed better compatibility than MWCNTs after 48 hours. Different mechanisms may be involved in the interaction between cells and the MWCNTs with different chemical surfaces.
authors.affiliation: Tianjin Key Laboratory of Biomedical Materials, Institute of Biomedical Engineering, CAMS and PUMC, Tianjin 300192, China.
authors.forename: Zhen-bao
authors.initials: ZB
authors.lastname: Liu
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.forename: Hai-yan
authors.initials: HY
authors.lastname: Wang
authors.forename: Hai-ling
authors.initials: HL
authors.lastname: Zhang
authors.forename: Lan-xia
authors.initials: LX
authors.lastname: Liu
authors.forename: Dun-wan
authors.initials: DW
authors.lastname: Zhu
authors.forename: Xi-gang
authors.initials: XG
authors.lastname: Leng
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D037742:Nanotubes, Carbon; D017382:Reactive Oxygen Species