title: In vitro apatite formation on nano-crystalline titania layer aligned parallel to Ti6Al4V alloy substrates with sub-millimeter gap.
abstract: Pure titanium substrates were chemically oxidized with H2O2 and subsequent thermally oxidized at 400 °C in air to form anatase-type titania layer on their surface. The chemically and thermally oxidized titanium substrate (CHT) was aligned parallel to the counter specimen such as commercially pure titanium (cpTi), titanium alloy (Ti6Al4V) popularly used as implant materials or Al substrate with 0.3-mm gap. Then, they were soaked in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 7 days. XRD and SEM analysis showed that the in vitro apatite-forming ability of the contact surface of the CHT specimen decreased in the order: cpTi > Ti6Al4V > Al. EDX and XPS surface analysis showed that aluminum species were present on the contact surface of the CHT specimen aligned parallel to the counter specimen such as Ti6Al4V and Al. This result indicated that Ti6Al4V or Al specimens released the aluminum species into the SBF under the spatial gap. The released aluminum species might be positively or negatively charged in the SBF and thus can interact with calcium or phosphate species as well as titania layer, causing the suppression of the primary heterogeneous nucleation and growth of apatite on the contact surface of the CHT specimen under the spatial gap. The diffusion and adsorption of aluminum species derived from the half-sized counter specimen under the spatial gap resulted in two dimensionally area-selective deposition of apatite particles on the contact surfaces of the CHT specimen.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama, 700-8530, Japan, satoshi@okayama-u.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hayakawa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Keita
authors.initials: K
authors.lastname: Uetsuki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shirosaki
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Osaka
mesh_terms: D000497:Alloys / Q000737:chemistry; D000535:Aluminum / Q000737:chemistry; D001031:Apatites / Q000737:chemistry*; D001826:Body Fluids; D001861:Bone Regeneration; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D019736:Prostheses and Implants; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000497:Alloys; D001031:Apatites; D020099:Coated Materials, Biocompatible; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D000535:Aluminum; D014025:Titanium