Novel well-adhered composite coatings on titanium plates consisted of Sr-doped hydroxyapatite, zein and TiO2 for biomedical applications

Composite coatings based on natural biocompatible polymer impregnated through hydroxyapatite (HAp)/freely-grown titanium oxide matrix were fabricated in one go onto titanium substrates. The substrates were subjected to simultaneous anodization/anaphoretic deposition (A/AD) methodology to check if the methodology can develop biomaterials with the advanced properties of strong adhesion, biocompatibility and bioactivity. HAp and strontium-doped HAp powders were synthesized ex-situ and used to demonstrate A/AD applicability to bone metabolism-enhancing (Sr-doped) materials. Similarly, zein is introduced to check if A/AD preserves its role of impregnating natural and biocompatible polymer. The main finding, emphasizing the improvement by A/AD, indicates the coatings are uniform, compact and well-adhered to the titanium surface, with all of the components present in their expected form. The initially smooth surface of anaphoretic zein coating appears roughened by incorporation of HAp, and especially by Sr-doped HAp. Consequently, the roughening improved the bioactivity and cell attachment with simultaneous excellent adhesion induced by zein. Bone metabolism is also expected to be improved since HAp appears to grow much from the Sr-doped HAp-based coating surface than from its bulk, if compared to the undoped counterpart.