Papers by Author: Kay Teraoka

Abstract: Titanium nitride (TiN) film on titanium film (Ti) was formed by magnetron sputtering method. Pure titanium substrates with TiN/Ti multi-layered films deposited using DC sputter-deposition machine in Ar gas atmosphere, in order to improve not only the blood compatibility of pure titanium but also the adhesion between the deposited TiN coating and the pure titanium substrate. The effects of the thickness of a pure titanium interlayer on adhesion of the TiN coating to the pure titanium substrate were investigated. And the effects of the TiN coating obtained in this study on blood compatibility were also investigated. The obtained multi-layered films looked yellow gold and appeared to be uniform and adhesive without any peel-offs. Based on the results of the platelet test, the ratio of the number of adhered platelets for the TiN/Ti film to that for the pure titanium substrate was estimated to be 0.54. Thus it was found that the platelet adhesion of the obtained TiN/Ti film was much smaller than the pure titanium, concluding that the TiN coating improved the blood compatibility.

Abstract: Calcium phosphate/ titanium oxide/ titanium/ plastic composite implants with 1.6-mm diameter and 7-mm length were successfully formed using a DC/ RF magnetron sputtering machine. The sample had no cracks and the surface of the sample was uniformly smooth. The chemical composition of the >10-nm-thick calcium phosphate layer was Ca: P: O=1.0: 0.79: 2.8. The sample was implanted into the tibia of an male 8-week-old SD rat for 28 days. When 0.70-μm sections of the tibia were prepared, the titanium layer with titanium oxide layer of the implant was not broken and the surfaces of the layer of the implant had not decomposed. The interaction between living bone and the implant could be clearly observed by light microscope and TEM.

Abstract: Titanium oxide/ titanium/ plastic composite implants were formed by coating commercially pure titanium thin films on the surfaces of plastic cylinders by DC magnetron sputtering method. The composite is uniformly formed and the surface of the composite implant is smooth. The implants in rat tibias were not broken and the films on the surfaces of the samples did not decompose. The samples with bone were able to cut by diamond knife and observations between bone and titanium oxide on titanium by TEM succeeded. Therefore, the composite is useful for implants or observations the interactions between titanium oxide and bone in detail.

Abstract: We fabricated a small α-TCP ceramic unit having four pods, named “Tetra-bone” employing a ceramic injection molding. Tetra-bone can keep uniform concave geometry among the pods as well as immobilizing each other. Owing to the monotony of Tetra-bone, weight of Tetrabones used can be converted into the number of Tetra-bones, volume that can be filled with Tetrabones, and the number of functional structures. By using Tetra-bones, bone defects can be filled with intentional geometry that helps to discuss the relation between geometric features of pores and bone formation.

Abstract: Commercially pure titanium thin films were uniformly formed on inner surfaces of tissue culture dishes by DC sputtering method. Then, the thickness of the film was about 30nm and the films were thin titanium oxide layer on commercially pure titanium. MC3T3-E1 cells were normally cultured on the dishes. Then, The films on the dishes were not broken and did not decompose. After 24 hours, observations of the sample from the direction of the cells' bottom surfaces adhered the titanium oxide on the commercially pure titanium film by an inverted optical microscope succeeded. Therefore, the new technique is useful for observations the interactions between titanium oxide and cells.

Abstract: This paper demonstrated a simple technique to seed the hydroxyapatite (HA) ceramic with 2-D cultured cells to establish an advanced mode of HA grafting. The HA beads with a through-hole were fabricated to have an oblate shape to keep an opening of the through-hole contact with 2-D cultured cells layer. The seeding was performed by leaving the HA beads in a culture dish with MG63 cells in culture. The through-hole trapped MG63 cells in a sheet form by 1-day seeding. After 5 days, the number of trapped cells increased about nine fold, forming cell clumps in the through-hole. The seeding of the HA beads was considered an easy and practical method to provide HA/Cell hybrids that would realize active bone forming orthopedic treatment.

Abstract: Our experiments of mouse osteoblast-like MC3T3-E1 cells cultured on a glass substrate showed that as surface roughness of a substrate increased, cell proliferation, cell differentiation and subsequent mineralization were reduced.

Abstract: Porous biodegradable microspheres were successfully obtained by an improvement single step and surfactant-free emulsion solvent evaporation method. The organic phase composed of PLA and dichloromethane was stirred in aqueous phase including Ca2+ ions to yield oil in water emulsion. During emulsification, stirring rate was increased so as to produce the W/O/W emulsion that results in microspheres with internal pores. The interface of internal water/oil was stable in W/O/W emulsion, which was explained that the bond between Ca2+ ions and carboxyl group of poly(lactic acid) would be stabilized the internal water/oil interface. Adding PO4 3- aqueous solution prompted to precipitate low crystallized hydroxyapatite on the external oil/water interface, and the precipitated hydroxyapatite would stabilizied microspheres formation. The resulting microspheres were approximately 100-500 µm with internal spherical pores of 10-200 µm in diameter. The porous biodegradable microspheres were expected to be utilized as injectable bone substitutes that allow bone ingrowth and bone regeneration.