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Preparation and characterization of biodegradable composite systems as hard tissue supports: bone fillers, bone regeneration membranes and scaffolds

Sezer, Ümran Aydemir
In tissue engineering applications, use of biodegradable and biocompatible materials are essential. As the tissue regenerate itself on the material surface, the material degrades with enzymatic or hydrolytic reactions. After a certain time, natural tissue takes the place of the artificial support. Poly(ε-caprolactone) (PCL) is one of the preferable polymers used in the restoration of the bone defects due to its desirable mechanical properties and biocompatibility. Addition of inorganic calcium phosphate particles in PCL structures can improve the mechanical properties as well as osteoconductivity; and presence of an antibiotic can prevent infection that may occur at the defect site. In this study, three forms of biodegradable hard tissue supports which are bone fillers, bone regenerative membranes and 3D scaffolds were designed and prepared. As biodegradable bone fillers, composite microspheres containing gelatin and β-tricalcium phosphate (β-TCP) were prepared and characterized. Synthesized β-TCP particles were coated with gelatin at different weight ratios and the effects of β-TCP/Gelatin ratio on the morphology of the microspheres were evaluated. Also, a model antibiotic, gentamicin, was loaded to these microspheres and release behaviours of the drug and its antibacterial effect on E.Coli was determined. The selected composition of these microspherical bone fillers were used as additives in the preparation of bone regenerative membranes and scaffolds. For this purpose, microspheres were added into PCL solution and processed by either solvent casting or freeze-drying in order to prepare bone regenerative membranes or scaffolds, respectively. For every material, the ratio of constituents (microsphere and PCL) was altered in order to obtain optimum properties in the resulted hard tissue support structure. The effects of the ratio of the microspheres to PCL in terms of morphological, mechanical and degradation properties of composite films, as well as in vitro antibiotic release and antibacterial activities against E.Coli and S.Aureus were investigated. For scaffolds, the effects of the ratio of the microspheres to PCL on the morphological, mechanical, pore size distribution, degradation properties and in vitro antibiotic release were examined.