Formation Of Hydroxyapatite Films Research Articles

Substrate dependent structural variations of biomimetic carbonated hydroxyapatite deposited on glass, Ti and sputtered ZnO thin films

The formation of hydroxyapatite films on glass, titanium (Ti), and sputtered ZnO is attempted to understand the crystal growth and its manipulation by substrates of a different kind. The substrates used are commercially available glass and polished Ti (99.9% purity), as-deposited, and annealed nanostructured ZnO thin films developed by pulsed DC magnetron sputtering, which are immersed in the calcifying solution for the nucleation and growth of the hydroxyapatite. The calcifying solution is obtained by mixing equal volumes of aqueous calcium (5 mM) and carbonate-containing phosphate (3 mM) solutions prepared at 37 °C and with a pH of ~7.4. X-ray diffraction, Raman spectroscopy, and Field Emission Scanning & Transmission Electron Microscopy (FESEM & FETEM) analyses reveal that the structure and morphology of the hydroxyapatite films are dependent on the growth duration, substrate type, and even on the post-deposition annealing of the sputtered ZnO substrates. The Ti substrate induces greater crystallinity in hydroxyapatite, whereas sputtered ZnO thin films cause a significantly reduced crystallinity. Moreover, the thicknesses of HAp are exacerbated by increasing deposition time irrespective of the substrate. FETEM analyses reveal the formation of needle-shaped hydroxyapatite nanocrystals grown on Ti and ZnO thin films. Thicker needle-shaped hydroxyapatite nanocrystals are observed when grown on Ti (~6–12 nm) than ZnO thin films (~4–6 nm). Further, the amorphous calcium phosphate phase coexists with nanocrystalline hydroxyapatite when ZnO thin films deposited at 50 and 70 W sputtering powers are used as the substrates. Both charged surfaces and the supersaturation of the calcifying solution impact the nucleation of hydroxyapatite onto substrates.

Effect of laser fluence and ambient gas pressure on surface morphology and chemical composition of hydroxyapatite thin films deposited using pulsed laser deposition

The dependence of the surface morphology and chemical composition of hydroxyapatite (HA) thin films on the laser fluence and ambient gas pressure during their formation by pulsed laser deposition was studied as the first step to investigate the effect of physical and chemical interactions between the ablated chemical species and ambient gas molecules on HA film formation. It was found that a higher fluence could decrease the number of large protrusions on the surface of HA thin films. However, too high a fluence caused a phosphorus deficiency from the stoichiometric value, particularly in the case of lower ambient gas pressure. It was also found that for lower fluences, the atomic species among the ablated chemical species were easily scattered by collision processes with ambient gas molecules. This was caused by the lower velocity of the ablated chemical species and higher ambient gas pressure, which induced a shorter mean free path. In addition, these collision processes played an important role in the adsorption, migration, and re-evaporation of the ablated chemical species on the substrate via chemical reactions.

B01 パウダージェットデポジションによるハイドロキシアパタイト膜形成に関する研究(OS12 ナノ加工と表面機能(1))

B01 パウダージェットデポジションによるハイドロキシアパタイト膜形成に関する研究(OS12 ナノ加工と表面機能(1))

Fabrication of xenogeneic bone-derived hydroxyapatite thin film by aerosol deposition method

Xenogeneic bone-derived hydroxyapatite (HA) was coated on Ti–6Al–4V substrate using aerosol deposition (AD) system. HA precursor powder was derived from bovine bone for the deposition. In aerosol system, submicron particles of HA were mixed with a carrier gas to form an aerosol flow in the aerosol chamber. The aerosol flow was through a tube to a nozzle, and then ejected into a deposition chamber. The effect of the beam incident angle on the HA film formation was investigated. The incident angle of the beam was changed from 0° to 60°. Homogeneous HA film with the thickness of 1-2 μm was fabricated by flattering of particles shape for the incident angle of 60°.

Hydroxyapatite Film Formation on Polylactic Acid Plate by Aerosol Beam Irradiation

A coating technology was developed to form hydroxyapatite (HAp) films on polylactic acid (PLA) plates by aerosol beam irradiation. The aerosol beam was composed of HAp particles of submicron size and helium gas. HAp films were produced at incidence angles of 0, 10, 20, and 30°, but the HAp films did not have good adhesion to the PLA plate when incidence angles were 0, 10, and 20°. To increase the adhesion strength between the HAp film and the PLA plate, the HAp film produced on the plate with an incidence angle of 30° was heated in an electric furnace. In vitro assessments using simulated body fluid (SBF) were performed to investigate the bioactivity of the HAp-coated PLA plate. The heat-treated HAp film did not peel off from the plate throughout the SBF test. The surface morphology and the crystallinity of the film produced in the SBF suggest that the HAp-coated PLA plate is bioactive.

Formation of Hydroxyapatite Films by Wet Processes

Formation of Hydroxyapatite Films by Wet Processes

Hydroxyapatite film formed by particle beam irradiation

A hydroxyapatite (HA) film was fabricated on the titanium (Ti) plate by an aerosol deposition method using HA submicron-size particle beam. Technology of HA film formation on the Ti is important for biomaterial production. In this process, neither substrate nor HA particles were heated during deposition. Effect of varying the beam incident angle on the HA film formation was investigated. The incidence angle of the beam was varied from 0° to 60° with a period of 20° by rotation of substrate. Adhesion strength between the HA film and the Ti plate was increased as the incident angle increased although its thickness was decreased. In the films formed at incident angle of 60°, the adhesion strength was found to be higher than 30 MPa. Possible formation mechanisms of the HA film dependent on the incident angle was discussed.