Facile fabrication of nanorod-assembled fluorine-substituted hydroxyapatite (FHA) microspheres

Nanorod-assembled FHA microspheres with different F contents were for the first time prepared through a facile one-step hydrothermal method. The effect of the reaction time and pH value of reaction solutions on the FHA morphology was investigated to elucidate the self-assembly process of FHA microspheres. The results showed pH values had significant effect on the morphology of the formed FHA crystals, which were self-assembled into sphere-like sturctures at high pH conditions and rod-like structures at low pH values. The results suggested that formation of FHA crystals with varied morphology may be directly related to Ca(2+) release kinetics from EDTA-Ca-Na2 at different pH conditions. Furthermore, it was found that the chemical stability of FHA microspheres was dependent on the F content in the materials, and high F contents in FHA microspheres lead to improved chemical stability. These results suggest that the prepared self-assembled FHA microspheres may be used for teeth substitution materials due to their unique hierarchical structures and controllable chemical stability.