Fabrication of hollow hydroxyapatite spherical granules for hard tissue regeneration and alternative method for drug release test

Hollow hydroxyapatite spherical granules were fabricated using template method. Alginate beads were used as template and they were coated with hydroxyapatite slurry. The coated beads were rapidly frozen using liquid nitrogen and burned out during sintering process. The size of the granules is the range of 1.0-1.5 mm. The shell is about 150 μm thick and the size of pores is about 10 μm in diameter, arranged in radial shape. The inner space and surface of granules were connected by pore channels which were formed by sublimation of water. Simulated body fluid was used to form apatite layer inner wall of granules and evaluated difference of fluid migration rate as concentration of slurry as an alternative drug release test. The possibilities of hollow hydroxyapatite spherical granules as bone grafts and drug carriers were discussed.