Fabrication of cobalt ferrite-hydroxyapatite coatings on Ti-6Al-4V with improved electrochemical behavior and hyperthermia potential for bone cancer therapy

: Development of bioceramic coatings on metallic implants (Ti-6Al-4V) with superior bone bonding ability and corrosion resistance is crucial in the field of biomedicine. The incorporation of ferrites such as cobalt ferrite into hydroxyapatite (HA) helps in achieving efficient nanocomposites that could be employed for magnetic hyperthermia applications. This work focusses on the fabrication of cobalt ferrite-hydroxyapatite composite coatings using an economical spin-coating method by varying the coating parameters and the studies were performed on the coatings. The produced coatings were characterized using XRD, FT-IR and SEM analysis. The wettability studies were done by measuring its contact angle, where the coatings exhibited hydrophilic behavior. The Vickers microhardness test was carried out to determine its mechanical properties and the coatings exhibited good hardness owing to their uniform nature. The bacterial growth restriction behavior of the coatings was conducted using two microorganisms ( Escherichia coli and Staphylococcus aureus ) and the number of viable bacterial colonies was measured. The coatings revealed good anti-bacterial activity and was higher for E. coli when compared to S.aureus . The biomineralization studies were performed and excellent bone-like apatite formation was observed on the coatings. The biocompatibility was assessed using L929 fibroblast cell lines and the cell viability was found to be higher for coatings unlike metal substrate. Early-late apoptosis of cells was identified using fluorescence staining (AO/EB) assay. The heating ability of the coatings were determined and the optimized coating was taken for in-vitro hyperthermia studies using human osteosarcoma (MG-63) cell lines, where the cell viability of the coatings declined significantly indicating cell death after hyperthermia treatment. Apoptosis and necrosis of the cells was analysed using Propidium Iodide staining. The electrochemical behavior of the coatings was observed by immersing in SBF solution using polarization and impedance studies in order to determine its corrosion resistance. According to these studies, the developed multifunctional coating can perform as a potential biomaterial in orthopedic applications.