Synthesis of Modified Hydroxyapatite (HAP) Substituted With Fe Ion for DDS Application

Syntheses of novel DDS particles were attempted using hydroxyapatite (HAP)-based materials. In this study, porous HAP substituted with Fe ion were successfully synthesized by a soft chemical processing and subsequent heat-treatments at 773 K in H₂ and air. After heat-treatments, porous HAP spherical particles with diameter of 10 to 20 mum were obtained. XRD results showed that these HAPs were identified to be a single hydroxyapatite without other phases. XANES results of heat-treatments at 773 K in air (HAP-A) showed that the local structure of Fe was similar to that of Fe₂O₃ and Fe₃O₄, whereas HAP heat-treatments at 773 K in H₂ (HAP-H) possessed the same Fe-local structure as FeO and Fe₂O₃. Results from EXAFS showed that HAP-H and HAP-A had no peaks more than 0.35 nm, suggesting that Fe ion hardly existed at positions of second and third neighbors. HAP-A and HAP-H was also easy to move with a permanent magnet and had the good bioactivity and biocompatibility.