Characteristics and In Vitro Biologic Assay of Apatite/Titania Composite Coatings on Ti–6Al–4V for Medical Applications
To improve the bioactivity, corrosion resistance, and long‐term biocompatibility of Ti–6Al–4V, apatite/titania composite coatings were synthesized on its surface using a H2O2‐oxidation
and subsequent accelerated biomimetic deposition method. Scanning electron microscopic (SEM) examination of coating surfaces and cross‐sections showed that the composite coatings were dense and uniform. The phase composition of titania inner layer and apatite outer
layer was investigated using transmission electron microscopy (TEM) and X‐ray diffraction (XRD). In addition, chemical composition of titania inner layer and apatite outer layer was determined using Fourier
transform infrared spectroscopy (FTIR). Considering the results from TEM, XRD, and FTIR analyses, it could be concluded that titania inner layer consisted of poorly crystalline anatase phase, and apatite outer layer was composed
of low crystalline, calcium‐deficient, and carbonated hydroxyapatite (HA). Based on variations of pH values of five‐time‐strength simulated body fluid (5SBF) during the accelerated biomimetic deposition, possible
processes for the formation of the apatite outer layer were discussed. The chemical stability of the apatite/titania composite coatings was also investigated using potentiodynamic polarization tests. After 3 days in culture, viability of MCF‐7 cells seeded
on uncoated and coated samples showed that the composite coatings were noncytotxic and could improve the biocompatibility of Ti–6Al–4V.