Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
Browse
3 results
Search Results
Doctoral Thesis Magnetic Levitation of Cells From Bone Marrow Origin(Izmir Institute of Technology, 2021) Anıl İnevi, Müge; Özçivici, Engin; Güven, SinanMagnetic levitation via negative magnetophoresis is a new label-free technology that is important in cell- and tissue-level bioengineering applications. Biofabrication applications of the technology is an area that still needs to be developed. In this doctoral thesis, 3D cellular structures with contrable size and cellular arrangement were formed and cultured with magnetic levitation using bone marrow-derived stem cells in both a miniature system that provides levitation between two magnets and a ring magnet-based large-scale system. First, a miniaturized magnetic levitation system that allows real-time imaging was produced and comprehensive protocols were described for its use for both single-cell level analysis and cell culture. With this setup, complex in situ 3D cellular aggregates were formed and their culture was maintained by levitation. Then, a new system that provides levitation on a single ring magnet was produced and used for biofabrication for the first time to overcome the reservoir volume constraint in the existing system and thus to create larger and symmetrical 3D cellular clusters. With the elimination of the upper limit in the system, the volume of the chamber was increased and the medium and biological structure transfer became easily applicable. It has been shown that this ring magnet-based magnetic levitation setup is suitable for cell culture, formation of millimeter-sized cellular structures with various cell types, and that pre- formed cellular structures can be combined by levitation. The low-cost and easy-to-use systems presented in this thesis have the potential to be applied in many areas such as tissue engineering and drug testing.Doctoral Thesis Molecular and Cellular Level Adaptations of Bone Marrow Mesenchymal Progenitor Cells To Chemical and Physical Signals(Izmir Institute of Technology, 2020) Baskan Erbilgiç, Öznur; Özçivici, Engin; Atabey, Safiye NeşeMechanical forces are the integral determinants in cell and tissue homeostasis and regeneration, and they can affect numerous biological process from proliferation to fate determination. Mechanical forces that possess low magnitude and high frequency characteristics are also known as low intensity vibrations (LIVs). These signals were studied widely on many cell types for regenerative purposes, however most of these studies select components of LIV signals (e.g. magnitude, frequency, duration, etc.) arbitrarily. Here, we addressed the effect of LIV applied frequency, LIV daily exposure time and fate induction on the viability of preadipocyte 3T3-L1 cells. For this, we performed a frequency sweep that was ranging from 30 to 120 Hz with 15 Hz increments applied for 5, 10 or 20 minutes during quiescent growth or adipogenesis for up to 10 days. Results suggest that the applied frequency and fate induction was an important determinant of cell viability, lipid droplet physiology, triglyceride concentration, cell density and adipogenic-specific gene expression while daily exposure time had no effect. These findings contribute to the effort of optimizing a relevant mechanical stimulus that can inhibit adipogenesis. On the other hand, random and aligned PAN/PPy nanofibers were investigated as a scaffold material for osteogenic differentiation of D1 ORL UVA mouse bone marrow mesenchymal stem cells. Cells were able to attach and grow on nanofibers confirmed by cell viability results. Stem cells that were cultured with osteogenic induction were able to mineralize on electrospun nanofibers based on alizarin red and Von Kossa dye staining. For aligned PPy nanofibers, mineralization occurred in the fiber alignment direction. Consequently, PAN/PPy nanofibrous mats in both random and aligned forms would be potential candidates for bone tissue engineering.Doctoral Thesis Development of Carbon Nanotube Embedded Polyacrilonitrile/Polypyrrole Electrospun Nanofibrous Scaffolds(Izmir Institute of Technology, 2017) İnce Yardımcı, Atike; Yılmaz, SelahattinIn this study, electrospun polyacrilonitrile (PAN)/ polypyrrole (PPy) nanofibers containing different PPy content (10, 25, and 50 wt%) were prepared. Different carbon nanotube (CNT) amounts (1, 2, 3, and 4 wt%) were embedded into PAN/PPy nanofibers to improve their mechanical and electrical properties. CNT functionalization was carried out to solve agglomeration problem and functional CNTs effects on PAN/PPy nanofiber morphology was examined. Alignment of nanofibers was studied to improve mechanical properties of nanofibers. Obtained PAN/PPy and PAN/PPy/CNT nanofibers were utilized as kerotinocytes scaffold. PAN/PPy/CNT and aligned and randomly oriented PAN/PPy nanofibers were examined for bone marrow osteogenic differentiation of mesenchymal stem cells (MSCs). 10 wt% PPy content was optimum in terms of mechanical properties and usage with CNTs. Higher strain was observed for 10 wt% PPy content which was 23.3 %. When as-grown MWCNTs were added into PAN/PPy, disordered nanofibers were formed. To improve interficial properties of these composites, as-grown CNTs were functionalized with H2SO4/HNO3/HCl solution. Upon functionalization, formation of hydroxylic and carboxylic groups were detected on the CNT surfaces. TEM examination of the nanofibers obtained with these CNTs showed decrease in beads formation. The functionalized CNTs were well dispersed within the electrospun nanofibers and aligned along the direction of nanofibers. The electroactivity of the fibers indicated that these nanofibers could be used as electrochemical actuator in acidic solutions. PAN/PPy and PAN/PPy/CNT nanofibers supported the attachment and proliferation of keratinocytes and osteogenic differentiation of MSCs. It was found that these nanofibers could be utilized as scaffolds for both cell types.