Biocompatibility Testing of Zein/Hydroxyapatite Composite Coatings on Titanium Substrate

The combination of hydroxyapatite with biopolymers like zein holds great promise for enhancing the properties of bone implants. Hydroxyapatite provides structural similarity with bone minerals, facilitating integration with natural bone tissue, while zein adds further benefits such as biodegradability, biocompatibility, and even potential antibacterial activity. By incorporating zein onto the surface of hydroxyapatite coatings, the implant becomes more compatible with the body's tissues, reducing the risk of rejection or adverse reactions. Additionally, the controlled biodegradability of zein allows for gradual replacement by natural bone tissue over time, promoting long-term stability and integration of the implant. This paper presents an investigation into the biocompatibility of zein/titanium dioxide (zein/TiO2), hydroxyapatite/zein/titanium dioxide (HAp/zein/TiO2) and strontium-doped hydroxyapatite/zein/titanium dioxide (Sr-HAp/zein/TiO2) composite coatings which obtained by in-situ anodization/anaphoretic deposition process. The biocompatibility of all prepared coatings was assessed by measuring cell viability through the MTT test using two different fibroblast cell lines: L929 and MRC-5. The results indicated an increase in the number of viable cells in all tested samples. The highest percentage of survival of healthy L929 and MRC-5 cells was observed with the zein/TiO2 coating. This suggests that zein is not only non-cytotoxic but also enhances cell proliferation, differentiation, and cell viability when present in the coatings. The morphology and adhesion of cells on the surface were analysed using SEM. Biocompatibility testing confirmed that the coatings are safe for use in both orthopedic and dental applications.