The Preparation and Characterization of Chitosan/Calcium Phosphate Composite Microspheres for Biomedical Applications.

In this study, we successfully prepared porous composite microspheres composed of hydroxyapatite (HAp), di-calcium phosphate di-hydrated (DCPD), and chitosan through the hydrothermal method. The chitosan played a crucial role as a chelating agent to facilitate the growth of related calcium phosphates. The synthesized porous composite microspheres exhibit a specific surface area of 38.16 m 2 /g and a pore volume of 0.24 cm 3 /g, with the pore size ranging from 4 to 100 nm. Given the unique properties of chitosan and the exceptional porosity of these composite microspheres, they may serve as carriers for pharmaceuticals. After being annealed, the chitosan transforms into a condensed form and the DCPD transforms into Ca 2 P 2 O 7 at 300 °C. Then, the Ca 2 P 2 O 7 initially combines with HAp to transform into β tricalcium phosphate (β-TCP) at 500 °C where the chitosan is also completely combusted. Finally, the microspheres are composed of Ca 2 P 2 O 7 , β-TCP, and HAp, also making them suitable for applications such as injectable bone graft materials.