Fabrication and Characterization of Zirconium Oxide Grafted Chitosan/Hydroxyapatite Scaffolds for Bone Tissue Engineering

In this study, zirconium oxide (ZrO₂)-containing chitosan/hydroxyapatite (CH/HAp) scaffolds were successfully fabricated using a vacuum freeze-drying technique. Subsequently, the impact of ZrO₂ incorporation on their structural, physicochemical, and biological performance was systematically investigated. XRD, FTIR, and SEM analyses confirmed that HAp and ZrO2 were distributed throughout the CH network, and indicated chemical interactions between CH and the incorporated components. Both CH/HAp and CH/HAp/ZrO₂ scaffolds presented a highly interconnected porous structure, together with a pore size range (9–88 µm) appropriate for tissue engineering. Enzymatic degradation studies revealed that after 35 days, the lysozyme induced degradation reached 63% for the CH/HAp and 30% for the CH/HAp/ZrO2 scaffolds, while scaffolds remained structurally stable in enzyme-free PBS. Flow cytometry analysis demonstrated that both CH/HAp and CH/HAp/ZrO₂ scaffolds maintained osteoblast viability (73.4%) without inducing significant apoptosis compared to control cells (p > 0.05). These results show that the degradation resistance of the scaffolds can be improved by the incorporation of ZrO2 without compromising the biological properties, making the CH/HAp/ZrO2 scaffold promising for bone regeneration.