title: Crystallinity of anodic TiO2 nanotubes and bioactivity.
abstract: Anodic TiO2 nanotubes were produced on titanium at 20 V using 1 M Na2SO4 and 0.5 wt% NaF. Oxidation for 3 hours produced amorphous tubes of diameter 100 nm and thicknesses 2 microm. Heat-treatments were done for 3 hours at different temperatures. 300 degrees C treatment converted the amorphous coatings to anatase. 550 and 700 degrees C treatments formed dual anatase and rutile; 850 degrees C treatment crystallized to rutile. The treatment at 700 degrees C produced an oxide surface with higher roughness, lower wetting angle and higher coating adhesion. Bioactivity of the as-oxidized and heated coatings were evaluated by treating them in a simulated body fluid (SBF) to form hydroxyapatite (HA) and the rates of HA formation were compared. Deposits of HA could be seen on the dual oxide structure within 3 days. HA was detected after 7 days in the anatase structure and only after 21 days in the amorphous and rutile structures. In vitro cell culture tests done using mouse osteoblasts indicated that, the 700 degrees C-heated surface showed higher levels of cell activity than the other surfaces. It is concluded that the dual rutile and anatase structure formed by heating the oxide at 700 degrees C is the best of the five surfaces tested.
authors.affiliation: Medical and Biological Engineering, Graduate School, Kyungpook National University, Daegu 700-412, Korea.
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: An
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Narayanan
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Hyo-Jin
authors.initials: HJ
authors.lastname: Lee
authors.forename: Tae-Yub
authors.initials: TY
authors.lastname: Kwon
authors.forename: Kyo-Han
authors.initials: KH
authors.lastname: Kim
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D002452:Cell Count; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003460:Crystallization; D017886:Durapatite; D006358:Hot Temperature; D051379:Mice; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects; D010316:Particle Size; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; C009495:titanium dioxide; D017886:Durapatite; D014025:Titanium