pH-Effect on Sinterability, Mechanical Properties and Cytotoxicity of Hydroxyapatite-Based Bone Grafts

Abstract

Hydroxyapatite (HA) based bone grafts were synthesized by sol-gel method at various pH values 5, 7, 9 and 12, respectively. In order to ascertain the influence of the obtained bone grafts on the morphology, sinterability and mechanical properties, each composition was sintered at 11500C, and quantitative phase analysis was characterized by XRD and FTIR. The microstructures were studied via SEM-EDX and the validation of mechanical properties was evaluated by compression and Vickers hardness tests. The density of HA synthesis samples with different pH values before and after sintering were measured. Besides, the cytotoxicity analysis were conducted for all grafts having various pH values. The experimental results revealed that the density and mechanical strenght of HA based bone grafts were increased with increasing pH value. The highest hardness and strength were obtained for the samples having pH=12. Furthermore, the samples with pH=12 exhibited the best densification and properties when compared to the samples at pH of 5, 7 and 9. The cytotoxicity tests also indicated that the pH=7-12 value showed no toxicity to osteoblast cells at 0,1 and 0,3 µM concentration, whereas HA synthesis sample at pH=5 value with 0,3 µM concentration induced significantly and reduced cell viability.