Papers by Author: Masahiko Inagaki

Abstract: The protein adsorption behavior was investigated for highly (001) oriented hydroxypatatite coatings (HACs). Highly (001) oriented (HO-) HACs and HAC with low orientation (LO-HAC) were prepared on titanium (Ti) substrates through a radio-frequency thermal plasma spraying method. Sintered HA pellets (S-HA) was also prepared as a control. The solution of 22 'g/100 'l PBS of the fluorescein-isothiocyanate (FITC) labeled bovine serum albumin (FITC-BSA), immunoglobulin G (FITC-IgG) and cytochrom c (FITC-CCC) was separately dropped on the surface of HACs and was incubated for 30 min. After the incubation, such HACs were washed with the PBS additionally supplemented with 125mM NaCl and observed using a fluorescence microscope. Fluorescence microscopic examination indicates that FITC labeled proteins somewhat adsorbed on the HACs, while proteins adsorbed little on S-HA surface. In particular, it can be seen that FITC-CCC adsorbed more prominently on the HO-HAC.

Abstract: Highly oriented hydroxyapatite (HA) coatings were prepared on titanium (Ti) substrates through a radio-frequency thermal plasma spraying method. XRD patterns showed that the HA coating layer had an structure with (00l) preferred crystal orientation. TEM observation showed that 200-800 nm-width prismatic crystals were formed in HA splats and the longitudinal axis of such prismatic crystals oriented vertical to the coating's surface. TEM images also indicate that the interface between prismatic crystals became compacted. SAD pattern show that the longitudinal axis of prismatic crystals corresponds to the <001> axis of HA.

Abstract: In vitro nucleation of apatite was studied over surface-modified Ti coatings prepared by reactive plasma spraying (RPS). An in-situ surface-modification of Ti particles is conducted by making use of plasma-enhanced reactions between the Ti particles and the reactive gaseous species in the plasma flame during plasma spraying. Surface-modified Ti coatings were deposited on Ti substrates by radio-frequency (rf)-RPS using a thermal plasma of Ar gas containing 1-6% N2 and/or 1-6% O2 at an input power of 16 kW. As a means of surface modification, Ti powders impregnated with 0.05-0.2 mol% Ca were also sprayed. Compositional changes in the coatings' surface after soaking in simulated body fluid (SBF) were examined by Fourier transform infrared spectroscopy (FT-IR) and thin film X-ray diffraction (TF-XRD). The Ti coatings prepared with Ar-O2 and Ar-N2-O2 plasma formed apatite after 3 days of soaking in SBF. On the other hand, no compositional change was observed in the surface of the Ti coatings sprayed with Ar-N2 plasma, even after 7 days of soaking in SBF. In SBF tests, we observed a retardation of apatite deposition for the Ca-added Ti coatings prepared with Ar-O2 and Ar-N2-O2 plasmas. Analyses by X-ray photoelectron spectroscopy indicated that the Ca impregnated in the RPS-Ti coatings formed a Ca-O compound.