title: Electrically polarized micro-arc oxidized TiO2 coatings with enhanced surface hydrophilicity.
abstract: The use of micro-arc oxidation titania (MAO TiO2) coatings to modify titanium surfaces improves the biocompatibility of implant surfaces. To obtain hydrophilic MAO TiO2 coating surfaces electric polarization, which induces surface electric fields in the materials and produces surface charges, was performed in this study. Electric polarization of the MAO TiO2 coatings was confirmed by measuring the thermally stimulated depolarization current. After electric polarization treatment the MAO TiO2 coatings did not exhibit any obvious changes in surface roughness, morphology, or phase components. X-ray photoelectron spectroscopy results indicated that electric polarization resulted in oxidation of the cathodic-faced surfaces and reduction of the anodic-faced surfaces. This result suggests that the existence of a concentration gradient of oxide ions/oxygen vacancies produced the stored space charge in the coatings. Reduction of the deionized water contact angle on the polarized MAO TiO2 surfaces was maintained for longer periods compared with the non-polarized surface. Our study demonstrated that metastable electric fields across the MAO TiO2 coating produced by electric polarization made it durably wettable by reducing the interfacial surface tension between the material and water.
authors.affiliation: Department of Inorganic Materials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
authors.forename: Chufan
authors.initials: C
authors.lastname: Ma
authors.forename: Akiko
authors.initials: A
authors.lastname: Nagai
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Toyama
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsutsumi
authors.forename: Takao
authors.initials: T
authors.lastname: Hanawa
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Yamashita
mesh_terms: D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D004560:Electricity; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions / Q000187:drug effects*; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction / Q000187:drug effects; D056951:Photoelectron Spectroscopy; D013499:Surface Properties / Q000187:drug effects; D014025:Titanium / Q000494:pharmacology*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D020099:Coated Materials, Biocompatible; D014867:Water; C009495:titanium dioxide; D014025:Titanium