Preparation of hollow hydroxyapatite microspheres

The preparation of hollow hydroxyapatite (HA) microspheres as potential drug-delivery vehicles was investigated. A lithium-calcium-borate (10Li(2)O-15CaO-75B(2)O(3)) (mol%) glass, made by fusing the components at 1100 degrees C for 1 h, was ground to a powder and passed through a flame at similar to 1400 degrees C to spheroidize the particles. The resulting glass microspheres (106-125 mu m in diameter) were reacted in 0.25 M K2HPO4 solution for 5 days at 37 degrees C and pH 10-12, resulting in the formation of porous, hollow microspheres of a calcium phosphate (Ca-P) material with external diameters similar to those of the original glass particles. Heat treatment at 600 degrees C for 4 h partially converted the Ca-P material to HA, as confirmed by X-ray diffraction, and also increased the strength of the hollow microspheres.