Phd Degree / Doktora

Permanent URI for this collectionhttps://hdl.handle.net/11147/2869

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  • Doctoral Thesis
    Development and Characterization of Novel Bioink by Using Decellularized Extracellular Matrix for Bone Tissue Engineering Applications
    (01. Izmir Institute of Technology, 2023) Kara Özenler, Aylin; Tıhmınlıoğlu, Funda; Havıtçıoğlu, Hasan
    Bone tissue engineering has focused on the development of functional scaffolds that can organize bone regeneration with appropriate structures and properties. Three-dimensional (3D) printing technology enables the development of personalized scaffolds. In addition, biological scaffolds obtained by decellularization have various advantages for developing natural-based scaffolds. The development of printable, patient-specific bioinks derived from decellularized extracellular matrix could provide 3D fabrication of tissues and organs with high potential to mimic native tissues. The presented thesis study demonstrates the development of various bioink compositions for bone tissue engineering applications. In this regard, bone tissues were decellularized with a novel method and then characterized in order to verify the removal of whole cellular components for eliminating immunological reactions. After the pulverization of tissues, decellularized bone (DB) particles were used as an additive within various ink combinations (alginate-, gelatin- and alginate-gelatin-based). Thus, various bioink formulations were developed containing DB particles, biopolymers and mesenchymal stem cells (MSC). All prepared bioinks were bioprinted, then the viability, proliferation and differentiation capacity of the cells inside the structures as well as the physical, rheological, and printability properties of the inks were assessed. The results revealed that all bioink combinations were suitable for bioprinting and the addition of DB particles improved cell proliferation and osteogenic differentiation in all bioink formulations. Alginate-based bioinks exhibited the greatest printability and shape fidelity, gelatin-based bioinks showed the highest cell proliferation and attachment, also, gelatin incorporation into alginate-based bioinks improved the biological activity of cells. In conclusion, cytocompatible, functional composite bioinks developed in this thesis study are of value for bone tissue engineering research in future to explore their functions in the living system and show complete bone regeneration while maintaining their stability for a long time.
  • Doctoral Thesis
    Natural and Synthetic Silica Incorporated Chitosan Composite Scaffolds for Bone Tissue Engineering Applications
    (İzmir Institute of Technology, 2016) Tamburacı, Sedef; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; Havıtçıoğlu, Hasan
    Recently bone tissue engineering studies have focused on the development of 3D scaffolds that can organize the tissue regeneration in natural way with appropriate porosity and reinforced the structure. Natural polymer-based composites have been focused with more attention than synthetic polymer composites for bone tissue engineering applications because of their biocompatibility and biodegradability. In this work, the goal was to combine the useful biomaterial properties of both chitosan and silica to design biocomposite organic/inorganic biomaterials for bone tissue engineering applications. The composite scaffolds were fabricated by freeze drying method bu using two different silicas; natural silica; Diatomite and synthetic silica, octa (tetramethylammonium) polyhedral oligomeric silsesquioxanes (OctaTMA-POSS). The effects of silica type and loading on the mechanical, morphological, chemical, surface properties, wettability and biocompatibility of composite scaffolds were investigated and characterized by using SEM, AFM, contact angle analysis, swelling study, protein adsorption assay, biodegradation and biomineralization tests. WST-1 cytotoxicity, cell proliferation with rezasurin and alkaline phosphatase activity assays were performed to determine biological activity of the composite scaffolds. In vitro biomineralization on scaffolds was determined by Von Kossa and Alizarin red staining. POSS and diatomite incorporation increased the surface roughness. Chitosansilica composites exhibited 82-90% porosity. Wet chitosan-silica composite scaffolds exhibited higher compression moduli compared to pure chitosan scaffold in 67.3- 81.4kPa and 78.1 to 107.6kPa range respectively. Average pore size range of chitosandiatomite and chitosan-POSS composite scaffolds was obtained as 15-180μm and 220- 300μm, respectively. Results indicated that chitosan-silica composites did not show any cytotoxic effect on 3T3, MG-63 and Saos-2 cell lines. Chitosan-silica composites were found to be favorable for osteoblast proliferation. Diatomite and POSS incorporation showed promising effects with enhancing ALP activity on hFob cells. Therefore, these composite scaffolds could be used for bone tissue engineering applications.