EMULSION-BASED PROCESSING AND CHARACTERIZATION OF BIOMIMETIC HYDROXYAPATITE MICROSPHERES BY USING CALCIUM PHOSPHATE CEMENTS

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2022-11-22

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Öndin, Nilsu

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Synthetic materials for bone defects have been widely used for biomedical applications. One of these materials is bioactive ceramic-based microspheres in the size range of couple 100s m. These microspheres are used for irregular defect filling operations due to high packing efficiency. The spherical shape also increases the surface area, reactivity, and cell adhesion. The osteoconduction (bone tissue growth) is the primary concern for hard-tissue replacements and grafts. Alpha-tricalcium phosphate (-TCP, -Ca3(PO4)2), a calcium orthophosphate with high solubility, is an attractive option in the powder form as a direct bone substitute material due to its cement-type reactivity setting to calcium-deficient hydroxyapatite (CDHAp, Ca9(HPO4)(PO4)5(OH)) in aqueous environments. The cement product is considered as a bioactive and biomimetic material due to its high chemical resemblance with the natural bone mineral. In this study, an emulsion-based microsphere formation has been accomplished by utilizing the cement nature of -TCP, enabling shape preservation for water-based -TCP slurry. Another structural component of the microspheres was an organic binder to improve and control the shaping ability, osteoconductivity and mechanical properties. The developed microspheres include -TCP:Ca-Alginate, -TCP:Gelatin, and -TCP:CSH (-TCP:Calcium Sulfate Hemihydrate) that are formed using water in oil (w/o) emulsion-based system enabling size and morphology control. The microsphere formation was finalized by long-term ex-situ hydration of spheres shaped by emulsion. The effects of the emulsion parameters; stirring efficiency, temperature on the microsphere size and morphology were investigated by parametric studies. The effects of binder type, concentration, and hydration media (DI water and buffer solution) on hydration of -TCP to CDHAp were studied by a parametrical approach. The microstructure and mechanical properties of different hybrid microspheres have been compared and reported.

Subject Keywords

Alpha Tricalcium Phosphate, Hydroxyapatite, Gelatin, Emulsion, Microsphere

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https://hdl.handle.net/11511/101175

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

N. Öndin, “EMULSION-BASED PROCESSING AND CHARACTERIZATION OF BIOMIMETIC HYDROXYAPATITE MICROSPHERES BY USING CALCIUM PHOSPHATE CEMENTS,” M.S. - Master of Science, Middle East Technical University, 2022.