Microstructure and in vitro Bioactivity of Metal Substituted Hydroxyapatite

Pure Hydroxyapatite (HAp) nanoparticles doped with Mn2+ and Fe3+ ions were synthesized using wet chemical method (WCM). Samples were characterized by different spectroscopic techniques such as XRD, FTIR, and ESR. The measurements revealed that a typical HAp powder pattern was obtained. Comparing with pure stoichiometric HAp, both Mn+2 substituted HAp (Mn-HAp) and Fe+3 substituted HAp (Fe-HAp) did not demonstrate significant structure deviation. Since ion exchange mechanism was applied for the preparation process, the morphology and particle size were not significantly affected. The FTIR absorption spectra of the doped samples are presented as absorption bands characterizing Mn+2, and Fe+3 which occupy different crystalline sites. The obtained data agrees well with that obtained from XRD. The crystal field parameters and degree of crystallinity for sites of these ions in the HAp matrix can be estimated. The addition of iron and manganese ions into hydroxyapatite results in improvement of the biological performance of the implant. Iron and manganese substituted hydroxyapatite has shown superior biological performance compared to its stoichiometric counterparts in vitro. The addition of such ions also enhances the magnetic properties of hydroxyapatite for the use in hyperthermia medical applications.