Hydrothermal synthesis of hollow hydroxyapatite microspheres with nano-structured surface assisted by inositol hexakisphosphate

In biomineralization, organic phases play important roles in synthesizing mineralized tissues with well controlled morphologies and structures. Inositol hexakisphosphate (IP6), a nontoxic natural polyphosphorylated carbohydrate found in mammalian cells and plant tissues, has been suggested to influence the crystallization of calcium phosphate (CaP) under ambient conditions. The present study investigated the effects of IP6 on the morphology of hydroxyapatite (HA) synthesized under hydrothermal conditions. Results showed that whisker-like HA crystals were obtained in the absence of IP6. In comparison, hollow HA microspheres consisting of nano-flakes were synthesized under the assistance of IP6. The difference indicated the impact of IP6 on the morphogenesis of HA. Transmission electron microscopy suggested that hollow microspheres were formed via a nanosphere-directed crystallization process.