Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Development and Use of Contactless Magnetic Manipulation Methodologies for the Formation of 3d Cardiac Models(01. Izmir Institute of Technology, 2022) Önbaş, Rabia; Arslan Yıldız, AhuIn this thesis, two contactless magnetic manipulation methodologies were introduced, which are magnetic levitation (MagLev) and biopatterning techniques. The optimization steps of both techniques were completed with NIH/3T3 mouse fibroblast cells. Later, 3D cardiac models were developed using H9c2 rat cardiomyocytes. For the MagLev technique, tunable 3D spheroids were obtained with changing initial cell seeding number, gadobutrol concentrations, and culturing time. For the biopatterning approach, a new bio-ink formulation, which comprises alginate, magnetic nanoparticles, and cells, was developed. Further, biopatterned cellular structures were fabricated in different shapes such as discs, rings, and rectangles under an external magnetic field. Later, characterization was done successfully via immunostaining of collagen I, F-actin, and DAPI. Moreover, cardiac-specific markers; cardiac troponin T and MYH6 were analyzed for both 3D cardiac spheroids and patterned 3D cardiac structures. Finally, doxorubicin was applied to evaluate the drug responses. IC50 values were calculated as 14.7 μM and 8.1 μM for 3D cardiac spheroids and 3D cellular structures respectively, while standard 2D cell culture was 3.5 μM which indicated 3D cardiac models were more resistant to drug exposure. In the last part of thesis, patterned 3D cardiac structures were fabricated using co-cultured hiPSC-derived cardiomyocytes and cardiac fibroblast cells via biopatterning methodology. Characterization was carried out successfully by immunostaining of α-actinin, collagen I, Cx-43, Troponin T, and DAPI. Taken together, to fabricate 3D cell culture models, MagLev and biopatterning-based contactless manipulation methodologies may be good alternatives to conventional 2D cell culture methods for tissue engineering applications, especially for drug screening.Doctoral Thesis Development of Magnetic Levitation-Based Sensitive Assays(01. Izmir Institute of Technology, 2020) Yaman, Sena; Tekin, Hüseyin Cumhur; Ergon, Mahmut CemMagnetic levitation (MagLev), in which an object is levitated with no support other than magnetic force and buoyancy force, is a powerful tool employed in many applications regarding the characterization of materials, biosensing of macromolecules, separating of cells, and monitoring of cellular events. Levitation of an object in MagLev depends on magnetic susceptibility and density of that object relative to its surrounding medium. In this thesis, MagLev-based miniaturized and affordable assay formats for biomolecule detection and cell separation were investigated. In this regard, a novel biomarker method detection in MagLev was developed using polymer microspheres as three-dimensional (3D) assay surfaces to capture target proteins and magnetic nanoparticles to label the captured target on the microspheres. Levitation heights of the microspheres conjugated to the protein were distinctly different than those of without protein. Thus, the magnetic susceptibility change of microspheres was precisely measured to convert the levitation height of microspheres into protein concentration. The principle developed for a biotinylated target protein was then investigated by designing sandwich immunoassays using model protein biomarkers: mouse immunoglobulin G and human cardiac troponin I. The developed assays enabled a protein detection range of femtogram-microgram per milliliter. In addition to biomolecule detection, using a lensless holographic microscopy-integrated MagLev platform, three different cell lines, bone marrow stem cells (D1 ORL UVA), breast cancer cells (MDA-MB-231), and human monocyte cells (U-937), were distinguished based on their density. The results revealed that the methods developed here could contribute to the magnetic MagLev-based sensitive and inexpensive bioanalytical applications.