title: Low pressure radio-frequency oxygen plasma induced oxidation of titanium--surface characteristics and biological effects.
abstract: OBJECTIVE
  This research was designed to investigate the effects of low pressure radio-frequency (RF) oxygen plasma treatment (OPT) on the surface of commercially pure titanium (CP-Ti) and Ti6Al4V. Surface topography, elemental composition, water contact angle, cell viability, and cell morphology were surveyed to evaluate the biocompatibility of titanium samples with different lengths of OP treating time.
  
  
  METHODS
  CP-Ti and Ti6Al4V discs were both classified into 4 groups: untreated, treated with OP generated by using oxygen (99.98%) for 5, 10, and 30 min, respectively. After OPT on CP-Ti and Ti6Al4V samples, scanning probe microscopy, X-ray photoelectron spectrometry (XPS), and contact angle tests were conducted to determine the surface topography, elemental composition and hydrophilicity, respectively. The change of surface morphology was further studied using sputtered titanium on silicon wafers. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and F-actin immunofluorescence stain were performed to investigate the viability and spreading behavior of cultivated MG-63 cells on the samples.
  
  
  RESULTS
  The surface roughness was most prominent after 5 min OPT in both CP-Ti and Ti6Al4V, and the surface morphology of sputtered Ti sharpened after the 5 min treatment. From the XPS results, the intensity of Ti(°), Ti(2+), and Ti(3+) of the samples' surface decreased indicating the oxidation of titanium after OPT. The water contact angles of both CP-Ti and Ti6Al4V were increased after 5 min OPT. The results of MTT assay demonstrated MG-63 cells proliferated best on the 5 min OP treated titanium sample. The F-actin immunofluorescence stain revealed the cultivated cell number of 5 min treated CP-Ti/Ti6Al4V was greater than other groups and most of the cultivated cells were spindle-shaped.
  
  
  CONCLUSIONS
  Low pressure RF oxygen plasma modified both the composition and the morphology of titanium samples' surface. The CP-Ti/Ti6Al4V treated with 5 min OPT displayed the roughest surface, sharpest surface profile and best biocompatibility.
authors.affiliation: School of Dentistry, National Taiwan University, Taipei, Taiwan ; Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Wan-Yu
authors.initials: WY
authors.lastname: Tseng
authors.affiliation: Institute of Polymer Science and Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Sheng-Hao
authors.initials: SH
authors.lastname: Hsu
authors.affiliation: School of Dentistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Chieh-Hsiun
authors.initials: CH
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Tu
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Shao-Chin
authors.initials: SC
authors.lastname: Tseng
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Hsuen-Li
authors.initials: HL
authors.lastname: Chen
authors.affiliation: School of Dentistry, National Taiwan University, Taipei, Taiwan ; Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Min-Huey
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Institute of Polymer Science and Engineering, National Taiwan University, Taipei, Taiwan ; Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Wei-Fang
authors.initials: WF
authors.lastname: Su
authors.affiliation: School of Dentistry, National Taiwan University, Taipei, Taiwan ; Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Li-Deh
authors.initials: LD
authors.lastname: Lin
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D006801:Humans; D008422:Materials Testing; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011846:Radio Waves; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D014025:Titanium; D010100:Oxygen