Date

2011

Author

Uysal, İdil

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This study aimed synthesizing hydroxylapatite (HA) and Zn2+, F- and Cl- doped HA by solution precipitation method. The synthesized compounds were sintered at 1100°C for 1h. For structural characterization, density of the samples were measured by Archimedes’ method. It was observed that Zn2+ addition increased the density significantly whereas F- caused a decrease and Cl- increased the density with a little amount. XRD was applied to the samples and it was found that co-doping of Zn2+ and F- ions decreased the unit cell volume of HA with F- addition. Other compositions gave fluctuated results in terms of unit cell volumes. HA phase and a little amount of CaO phase were detected in some samples. FTIR spectroscopy was used to detect whether Zn2+, F- and Cl- ions were incorporated to the HA structure or not by observing the bands corresponding to the bonds in the molecules. The amount of addition was also detected by FTIR. Results showed that ion incorporation to the HA structure was done successfully. SEM images were v analyzed and grain sizes of samples were calculated by Rietvelt analysis. Grain sizes of the samples increased by Cl- addition and decreased by Zn2+ and/or F- addition. For mechanical characterization, Vickers microhardness test was applied. Fracture toughness was calculated from Vickers microhardness results. According to the results, the highest microhardness values were found for F- and Zn2+ co-doped samples. It was also shown that fracture toughness decreased by Zn2+ addition. However, Zn2+ and F- co-doped samples gave higher fracture toughness results when compared with pure HA. Cl- addition also decreased the fracture toughness. The best compositions in terms of structural and mechanical properties was chosen as Zn2+ and F- co-doped samples and biological characterization was applied to these samples. Saos-2 cell line was used in biological examinations. For biological characterizations, Alamar Blue™ assay to detect viability and alkaline phosphatase activity (ALP) assay to detect differentiation were done. It was observed that 2 mol.% Zn2+ addition increased the cell viability and alkaline phosphatase activity. 1 mol.% F- addition also improved cell viability and alkaline phosphatase activiy. SEM images were analyzed to observe the morphology of the cells on HA and selected doped HA discs. In accordance with Alamar Blue™ assay and alkaline phosphatase activity assay, cells showed dendritic shapes on 2 Zn and 2 Zn 1 F sample which was the indicator of good material-cell interaction. Dissolution test was also applied by immersing the samples in simulated body fluid (SBF). pH change and SEM images for Ca2+ deposition were investigated. Increase in pH change with time was observed. F- included samples gave the lowest pH change results, especially 2 Zn 1 F. Dissolution pits and some apatitic formations were observed in SEM images.

Subject Keywords

Hydroxyapatite

URI

http://etd.lib.metu.edu.tr/upload/12613481/index.pdf
https://hdl.handle.net/11511/20952

Collections

Graduate School of Natural and Applied Sciences, Thesis