Mehtap Demirel

Synthesis and characterization of Bioglass-based bone grafts with Gelatine substitution for biomedical applications

BACKGROUND Syntesizing alternative bone graft materials are important in biomedical applications. Their morphology, mechanical properties and cell viability plays an important role in tissue engineering. OBJECTIVE Bioglass (B) based bone grafts with Gelatin (G) substitution were syntesized via the sol-gel method and were compared with various Gelatin and Bioglass concentrations (wt%). METHODS Syntesized bone grafts were characterized by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) to show the structural and morphological changes of the fabricated B-based bone grafts. RESULTS It was demonstrated that the concentration of pore size increased with increasing amounts of Gelatin in wt%. The biograft-B40G20 produced the highest flexture strength and hardness. Increasing the pore size caused a decrease in hardness and flexture stress of B-based biografts. CONCLUSIONS Cell viability tests were conducted on the fabricated biografts and it was shown that the cell viability increased in fabricated B-based bone grafts.

Synthesizing selenium- and silver-substituted hydroxyapatite-based bone grafts and their effects on antibacterial efficiency and cell viability

Abstract Hydroxyapatite (HA)-based biografts with selenium (Se) and silver (Ag) substitutions were synthesized using the sol-gel method. The synthesized HA-based biografts at various Se and Ag quantity ratios (wt%) were characterized via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDX). Escherichia coli (JM103) and Gram-positive Staphylococcus aureus (ATCC29293) bacteria were used for the cell viability tests by performing the MTT assay. During antibacterial tests, it was determined that the synthesized biografts showed significant antimicrobial activity on E. coli and S. aureus; however, some materials were effective on Gram-negative E. coli, but had no effect on Gram-positive S. aureus. In vitro cell viability tests revealed that some of the synthesized biografts such as H30Ag10Se15 and H40Ag20Se10 provided the highest cell viability rates compared to those in the control group.

The effect and characterization of newly synthesized SrBr2 reinforced bone grafts on structure and cell viability

In this study, a highly durable SrBr2 compound was added to Ca(NO3)2·4H2O, KOH, NaNO3, P2O5, and urea (CO(NH2)2) compounds at different ratios (wt 10–30%); biografts were synthesized in different compositions using the sol gel method They were characterized using X-ray diffraction, Fourier transform infrared spectrometer, scanning electron microscope, and mechanical tests e.g. hardness and compression. Structural, mechanical properties and cell viabilities of the synthesized biografts were comparatively examined. Fourier transform infrared spectrometer and X-ray diffraction analysis results showed that, including SrBr2, hydroxyapatite had formed in the biografts. Also, hardness and compression tests revealed that compressive stress and hardness values of the grafts increased as the amount of SrBr2 increased. The cell viability ratios also enhanced with the amount of SrBr2 increased in the synthesized biografts.Graphical Abstract

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

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.