Effect of alginate as polymer matrix on the characteristics of hydroxyapatite nanoparticles

Hydroxyapatite (HA) nanoparticles were prepared in the presence of alginate, which exhibited spherical shapes. The size of HA nanoparticles decreased with increasing the content of alginate. The HAs synthesized in the presence of alginate agglomerated, leading to the formation of the secondary particles with a size of hundreds nanometer and very narrow size distribution. Thermal treatment also affected the aggregation behavior and particle shape of HAs. The mixture of spherical and rod-like nanoparticles was observed by thermal treatment at 600 °C. FT-IR, XRD and XRF analyses confirmed that the stoichiometric HA nanoparticles could be synthesized with using alginate, in which the Ca/P molar ratio was ranged from 1.74 to 1.68. These HA nanoparticles showed the same crystalline phase with that of the stoichiometric HA after thermal treatment. In addition, the content of alginate contained in the products could affect the initial deposition rate of bone-like apatite on the surface of HA nanoparticles.