Development of cobalt ferrite-hydroxyapatite nanocomposites as a promising theranostic tool for advanced orthopedic applications

A desirable biomaterial, hydroxyapatite (HA) has been extensively employed for different orthopedic applications due to its close resemblance with natural bone apatite. The incorporation of ferrites into HA creates a promising platform for efficient nanocomposites with exceptional properties suitable for magnetic hyperthermia and bioimaging applications. The optimization of the concentration of ferrite that can be incorporated into HA which exhibit higher MRI contrast and hyperthermia efficiency is required to develop efficient composites which can be further utilized for advanced applications. Therefore, in this study, cobalt ferrite-hydroxyapatite (HA-CoFe 2 O 4 ) composites were synthesized using a refluxing sol-gel method and the obtained composites were characterized using XRD, FT-IR, SEM and VSM analysis. Both XRD patterns and FT-IR spectra confirmed the existence of both the HA and CoFe 2 O 4 phases and the morphological analysis revealed the formation of highly agglomerated clusters. The composites were found to be ferromagnetic with higher magnetization and coercivity. The increased coercivity and magnetization was observed for the composite with increase in concentration of CoFe 2 O 4 . The heating efficacy of the composites were evaluated and they were able to achieve hyperthermia temperature within short duration. The enhanced T2 contrast efficiency was confirmed through relaxivity measurement and the value improved with the increase in CoFe 2 O 4. The anti-bacterial activity of the composites was analyzed using disc diffusion method and it was found to improve with the inclusion of CoFe 2 O 4 . The in-vitro cytotoxicity assay was performed using MTT assay with L929 fibroblast cell lines and all the composites were biocompatible. The cell viability deceased with the concentration of CoFe 2 O 4 , however only at 500 μg/ml did the cell viability declined over 70 % at 48 h incubation which clearly suggest that these developed composites could be utilized for biomedical applications. • Refluxing sol-gel synthesis of HA-CoFe 2 O 4 composites with varying concentration of cobalt ferrite. • The structural analysis revealed the existence of both HA and CoFe 2 O 4 phases and the inclusion of cobalt ferrite resulted in the formation of highly agglomerated clusters. • The composites exhibited ferromagnetic behavior with increased coercivity and accounted for its superior hyperthermia efficacy and T 2 MRI contrast enhancement. • The cytocompatible nature of the composites were confirmed using MTT assay with L929 fibroblast cell lines.