title: Characterisation of calcium phosphate/titanium dioxide hybrid coatings.
abstract: The role of titanium dioxide (TiO2) as a means to engender enhanced stability into calcium phosphate (Ca-P) coatings has been well recognised. Several different methods have been used to create such Ca-P/TiO2 hybrid layers on a range of substrates. This paper reports the properties of a Ca-P/TiO2 system created by the sputter deposition of hydroxyapatite onto a titanium surface and the subsequent thermal diffusion of TiO2 through the porous Ca-P layer. The role of temperature in determining the surface contribution from TiO2 has been determined. Coatings annealed up to 600 degrees C did not exhibit any hybrid nature in the uppermost surface, however the coatings annealed to 700 degrees C did show the presence of both HA and rutile TiO2. The surfaces annealed to 800 degrees C were predominantly rutile TiO2. It was also observed that the Ca/P ratio decreased with increasing annealing temperature and that the coating annealed to 700 degrees C had a value of 1.82 +/- 0.07, which was closest to stoichiometric HA. Furthermore, the coatings that were annealed to 700 degrees C displayed a Ca-P/TiO2 hybrid nature, specifically in their uppermost surface and supported the growth and proliferation of osteoblast-like cells more readily when compared to the HA coatings or the rutile TiO2 surfaces.
authors.affiliation: Northern Ireland Bioengineering Centre/Nanotechnology and Advanced Materials Research Institute, University of Ulster at Jordanstown, Shore Road, Room 25A18, Newtownabbey, Co. Antrim, Northern Ireland, UK. ar.boyd@ulster.ac.uk
authors.forename: A R
authors.initials: AR
authors.lastname: Boyd
authors.forename: G A
authors.initials: GA
authors.lastname: Burke
authors.forename: H
authors.initials: H
authors.lastname: Duffy
authors.forename: M L
authors.initials: ML
authors.lastname: Cairns
authors.forename: P
authors.initials: P
authors.lastname: O'Hare
authors.forename: B J
authors.initials: BJ
authors.lastname: Meenan
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013057:Spectrum Analysis; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C009495:titanium dioxide; C020243:calcium phosphate; D014025:Titanium