Papers by Author: Tatsuya Miyajima

Abstract: Natural bone is a complex material with well-designed architecture. To achieve successful bone integration and regeneration, the constituent and structure of bone-repairing scaffolds need to be flexible and biocompatible. HAp, as the main composition of bone minerals, has excellent biocompatibility, while CMC comprised of a three-dimensional network were high flexibility. Therefore, CMC/HAp composite have been attracted attention due to the development of bone tissue engineering. In this work, carboxymethyl cellulose (CMC)/hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂; HAp) composite have been developed as three-dimensional scaffold for bone tissue engineering. Scanning electron microscopy revealed that the CMC/HAp composite have sheet-like structure. The amount of precipitated HAp of CMC/HAp composite was investigated using Thermogravimetric analysis. The amount of precipitated HAp in products prepared with 100 mg CMC was 49.8 wt%, while the amount of precipitated HAp in products prepared with 1000 mg CMC was 22.3 wt%. These results revealed that the amount of precipitated HAp in CMC/HAp composite was affected by CMC amount as prepared.

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.