Micro-structured hydroxyapatite microspheres for local delivery of alendronate and BMP-2 carriers

Abstract This study describes the preparation of hydroxyapatite microspheres for local delivery of alendronate and BMP-2. The hydroxyapatite microsphere preparation was initiated by enzymatic decomposition of urea and accomplished using an emulsification process (water-in-oil) for nucleation and growth of hydroxyapatite within the microemulsion. The microspheres obtained were then sintered at 500 °C. Scanning electron microscope (SEM) indicated that the microspheres have particle-in-sphere morphology, so called ‘microstructured microspheres’. The viability of L-929 cells in the presence of sintered microspheres was 85%. The adsorption efficiencies for alendronate varied from 27.2% to 84.1% depending on the loading conditions. For BMP-2 loading, 79.2% was absorbed on the microspheres when a BMP-2 concentration of 25 μg/ml was used.