Synthesis of fluoride-releasing strontium-substituted porous apatite microspheres for bone osteoporosis treatment

The traditional strategy to synthesize porous microspheres is focused on the template method, which might be hazardous to health and environment. The strontium and fluoride substituted hydroxyapatite (Sr-FHA) micro-spheres were successfully fabricated only through the Sr ion assistant and the optimization of hydrothermal reaction conditions. The morphology observation showed that the fabricated Sr-FHA porous microspheres in diameters of about 30 & mu;m were assembled by two-dimension nano-sheets with 30-70 nm in thickness, up to 4-5 & mu;m in length and about 2 & mu;m in width. Sr substitution can change the crystallinity of apatite and promote the formation of microsphere structure. Moreover, the occupancy types of Sr on Ca affected the actual contents of fluoride substitution, which consequently affected the crystal microstructure of apatite, self-assembly of mi-crospheres and the release process of fluoride ions. The synthesized Sr-FHA microspheres with large specific surface area (75.4 m2/g), large pore volume (0.43 cm3/g) and complex porous structure resulted in sustained release properties. The ionic extracts of Sr-FHA porous microspheres promoted the proliferation of human osteoblast-like cells (MG-63). The fabricated Sr-FHA microspheres may be a potential candidate as bioactive fluoride therapy carriers for the treatment of osteoporosis and bone defects.