Synthesis of magnetic hydroxyapatite by hydrothermal–microwave technique: Dielectric, protein adsorption, blood compatibility and drug release studies

The hydroxyapatite (HAp) nanoparticles with some magnetic ions (cobalt (Co), iron (Fe), nickel (Ni) etc) exhibit strong ferromagnetic properties, which play an important role in the targeted drug delivery and magnetic hyperthermia treatment of the tumours. Cobalt (Co2+) doped HAp (Co–HAp) was synthesized using a combinatorial methods of hydrothermal and microwave irradiation. The crystallinity was found to reduce with an increase in Co2+ incorporation. Pristine samples consisting of monodispersed spheres of size 121 nm were diamagnetic. The incorporation of Co2+ (44 ppm) leads to a significant reduction in size (55%) and change in morphology (spherical to hexagonal rods). The presence of 139 ppm of Co2+, lead to the formation of a super paramagnetic porous structure consisting of hexagonal nanorods and nanospheres. There was a drastic increase in the magnetization (1.2×10−2 to 6.1×10−2 emug−1) and dielectric constant (1–2476) on incorporation of cobalt. The Co–HAp exhibited better protein adsorption due to the increase in positive surface potential on addition of Co2+, as confimed by the zeta potential analysis. Further, Co2+ ions incorporated HAp exhibited enhanced haemocompatibility and sustained release of an anticancer drug (5-fluorouracil). This cobalt ion doped HAp could be a promising material for magnetic imaging, drug delivery and hyperthermia treatment.