Fabrication of chitosan-modified hydroxyapatite/zirconia/45S5 bioglass composite bone scaffold using 3D printing: Mechanical and biological properties

In this thesis, hydroxyapatite (HA) based bioceramic bone scaffolds with high mechanical strength, biocompatibility and antibacterial properties were developed for use in bone tissue engineering. The main purpose of the study was to improve both mechanical and biological properties by adding 3YTZP zirconia and 45S5 bioglass to HA, and to produce samples with chitosan coating and antibacterial activity using DLP type 3D printer technology. Within the scope of the study, three different compositions (HA/ZrO₂ - HZ, HA/45S5 - HG, HA/ZrO₂/45S5 - HZG) were prepared and their physical, structural, mechanical and biological properties were evaluated comprehensively. The samples produced with the 3D printer had a pore size of >500 µm and >90% porosity, which mimic the cancellous bone tissue, and a high density structure was obtained by sintering at 1250°C. The HZG samples, which gave the most successful results, especially in the HZG-3 samples, achieved 281.2 MPa compressive strength, 68.07 MPa flexural strength and 1.25 MPa m⁰⁵ fracture toughness, with improvements of 66%, 368% and 44%, respectively, compared to the HA samples without additives. These values reveal that the developed scaffolds are mechanically compatible with cancellous bone tissue. In cytotoxicity analyses, the HZG-5 sample exhibited 95.46% cell viability, and in SEM analyses, it was observed that the cells adhered strongly to the surfaces and formed filopod-lamellipod structures. In addition, the HZG+C sample, which was given antibacterial properties with chitosan coating, significantly reduced the number of live bacteria against E. coli and S. aureus bacteria (p<0.05). In conclusion, this study has successfully produced bioceramic scaffolds with HA/3Y-TZP/45S5 composition using DLP type 3D printer technology for the first time in the literature, and promising, multifunctional biomaterials for bone tissue repair have been presented.