Ph.D. Theses
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Browsing Ph.D. Theses by Subject "Biomedical engineering."
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Item Biodegradable hydrogels and cryogels for biomedical applications, in particular bone tissue engineering(Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2023., 2023) Güven, Melek Naz.; Avcı, Duygu.This work consists of synthesis, characterization and evaluation of bisphosphonate, bisphosphonic acid or carboxylic acid functionalized polymers, macromers and their crosslinked network hydrogels and cryogels for various biomedical applications in particular bone tissue engineering. In the first project, poly(amido amine) (PAA) macromers functionalized using sodium alendronate, and their cryogels were synthesized and the effects of the macromer structure as well as bisphosphonic acid content on the cryogel properties such as swelling, degradation, mineralization, and mechanical properties were investigated. In the second project, novel PAA polymers and macromers functionalized using tetraethyl vinylidene bisphosphonate were synthesized. The polymers’ rheological properties were investigated in the context of their interaction with cations such as Ca2+ and Fe3+. Subsequently, both bisphosphonate-functionalized and control macromers were copolymerized with HEMA to prepare hydrogels. The swelling, degradation, mechanical, biocompatibility, cell adhesion and biomineralization characteristics of these hydrogels were thoroughly examined to assess their suitability for potential applications in tissue engineering and the effect of bisphosphonate functionalization. The third section reports the synthesis of four novel highly water soluble, carboxylated diacrylate and diacrylamide macromeric crosslinkers based on meso-2,3-dimercaptosuccinic acid and their hydrogels with 2- hydroxyethyl methacrylate. The study is focused on examining how macromer structure and amounts enable control of the swelling, degradation, mechanical properties, and metal adsorption capabilities of the hydrogels. In the last part, phosphate functionalized double network hydrogels were prepared using dual curing method, an aza-Michael reaction of 1,4- butanediamine with poly(ethylene glycol) diacrylate or N,N’- methylene bisacrylamide followed by radical photopolymerization of 10-methacryloyloxydecyl dihydrogen phosphate, and their potential use for tissue engineering applications were investigated.Item Redox-responsive biodegradable polymeric materials for biomedical applications(Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Çalık, Filiz.; Sanyal, Rana.; Sanyal, Amitav.In recent years, biodegradable and stimuli-responsive polymeric materials have gained importance in cancer research and biomedical applications. Such materials can be used as implants in the body and a nano-sized drug delivery system. Within the scope of this thesis, three different stimulus- sensitive biodegradable polymer dendron conjugate systems were prepared, and micellar nanostructures were obtained with these structures. The hydrophobic drug was physically loaded into the micelle structures in the first three projects. In the first and second projects, a targeting group was used to increase the efficiency of the drug delivery system. These micellar carriers make the hydrophobic drug water-soluble in body fluid and use both passive and active targeting pathways to ensure that the drug is collected in tumor tissues. The size of micellar structures was appropriate in all three projects when examined in terms of their suitability for delivery based on the enhanced permeability and retention (EPR) effect. The first two projects used cyclic RGDfK as the targeting group. It was observed that the drugs incorporated into the micellar nanostructures with the targeting group accumulated more effectively in the breast cancer cells. Doxorubicin was used as a chemotherapy agent. The last study synthesized cryogels containing varying amounts of a thiol- reactive monomer. Facile and reversible functionalization of cryogels were demonstrated through the attachment of a fluorescent dye (Bodipy-SH) and bioactive ligands such as biotin-thiol and mannose-thiol to recognize Streptavidin and Concanavalin-A, respectively. The proteins bound to the cryogels were amenable to release through treatment with a thiol-containing reducing agent such as dithiothreitol (DTT). Overall, the novel thiol reactive macroporous cryogel structures will be a fascinating platform for various biomedical applications where a catch and release approach of analytes is necessary.