Papers by Author: Emile Hideki Ishida

Abstract: Novel porous wollastonite microspheres for releasing silicate and calcium ions were prepared by electrospraying using a hydrolyzed alkoxide. Wollastonite formed in the microspheres by heating the electrosprayed precursor microspheres at 850 °C for 2 h. Numerous pores of 100-300 nm in diameter were newly formed at the surface of the microspheres. The size of porous wollastonite microspheres was determined to be 1-5 µm in diameter.

Abstract: A novel poly(lactic acid) (PLA)/calcium carbonates hybrid membrane containing siloxane was prepared using aminopropyltriethoxysilane (APTES) for biodegradable bone guided regeneration. The PLLA in the membrane was an amorphous phase. By heating the membrane at 100 °C for 1 h, the PLLA in the membrane crystallized. Numerous pores of 0.5-1 ,m in diameter were newly formed at the surface. After soaking the membranes before and after heat-treatment in simulated body fluid, the amount of silicon species in SBF released from the membrane after heat-treatment was higher than that before heat-treatment. A test of osteoblast-like cellular proliferation on the membrane showed the membrane after heat-treatment has much higher cell-proliferation ability than that before heat-treatment.

Abstract: After hydrothermal treatment of tricalcium phosphate (TCP), calcium deficient hydroxyapatite (HA) with much amount of a-surface (h00) was obtained. It was considered that c-surface of HA had larger surface tension than that of a-surface, therefore HA crystals elongated along c-axis of <001> directions. By using hydrothermal treatment, difference of surface tension was affected crystal growth of HA. The adsorption property of HA will be controlled by designing of HA morphology, because different crystal surfaces have different properties.

Abstract: Porous granules of β-tricalcium phosphate (β-Ca3(PO4)2; β-TCP) were prepared from porous hydroxyapatite granules with calcium deficient composition synthesized by hydrothermal method. The β-TCP granules were composed of rod-shaped particles of about 10-20 µm in length. Rod-shaped particles were locked together to make micro-pores, and the size of micro-pores formed by tangling of rod-shaped particles was about 0.1-0.5 µm. The granule size, particle size, and micro-pore size could be controlled by our unique method. The porous granules of β-TCP must be suitable for the bone graft material and for scaffold of cultured bone.

Abstract: Porous composites of magnetite / hydroxyapatite with bimodal pore size distribution were prepared by hydrothermal method. Magnetite particles of about 1 µm in size with polyhedral shape were dispersed into hydroxyapatite porous matrix. The hydroxyapatite particles were rod-shaped crystals and the size of crystals were about 10 µm in length with the aspect ratio of over 25. Rod-shaped hydroxyapatite crystals were locked together to make micro-pores of about 0.8 µm in size. In addition, macro-pores of about 400 µm in size were prepared by our unique method. Hydroxyapatite in this composite was non-stoichiometric hydroxyapatite with calcium deficient composition. This composite must have the advantage of adsorptive activity and osteoconductivity, because the hydroxyapatite has many specific crystal surface and micro-pores. The composites of magnetite / hydroxyapatite must be suitable for the hyperthermia therapy of cancer in bones.

Abstract: Porous apatite carrier with high selectivity of adsorption was prepared by using hydrothermal method. α-TCP as the starting material was changed into hydroxyapatite at the temperature above 120 °C for the period over 3 h under saturated vapor pressure. Porous apatite carriers were composed of rod-shaped crystals with non-stoichiometric hydroxyapatite composition. Since HA crystals had rod like shape, the area of a-surface was larger than that of c-surface. This carrier had higher selectivity for bovine serum albumin (acidic protein) than lysozyme chloride (basic protein). This material must be suitable as scaffold for cultured bone, for bone graft material and for drug delivery system (DDS).

Abstract: Ceramics of hydroxyapatite (Ca10(PO4)6(OH)2: HA) and β-tricalcium phosphate (β-Ca3(PO4)2: β-TCP), were prepared by spark plasma sintering (SPS) at the temperatures from 800 °C to 1000 °C for 10 min with a heating rate of 25 °C·min-1. The HA ceramics prepared at 900 °C and 1000 °C showed transparency. On the other hands, transparent β-TCP ceramics was obtained by SPS at 1000 °C. In analysis of the densification behavior during sintering of HA and β-TCP by SPS, dominant sintering mechanism was plastic flow in the early stage of densification. Transparent ceramics should be the most suitable materilas to investigate the interface between human cells and ceramics.