Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Arslan Yıldız, AhuSubject: search.filters.subject.Tissue engineering

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Now showing 1 - 5 of 5
  • Master Thesis
    Development and Characterization of Biomimetic Peptide-Based Bioink for Dental Tissue Engineering
    (01. Izmir Institute of Technology, 2023) Altan, Zeynep; Arslan Yıldız, Ahu
    Recently, the role of molecular control in the tooth mineralization process has received much attention. Biomimetic scaffolds have been started to use in dental tissue engineering and regeneration due to their high applicability, biocompatibility, biodegradability, and mineralization capability. In this thesis, a hybrid biomimetic bio-ink; P11-4 peptide-based Quince Seed Hydrogel (QSH)/Gelatin (Gel) is used in 3D cell culture studies for dental tissue engineering applications. Pristine QSH, QSH/Gel, and P11-4/QSH/Gel bio-inks were characterized by FTIR and viscosity analysis, and their 3D bioprinting parameters were optimized. Hydrogels were crosslinked via 1-Ethyl-3-(3-dimethylaminopropyl) Carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) coupling reaction and various hydrogel concentrations were investigated for scaffold fabrication. Characterization of produced scaffolds was performed by SEM imaging, mechanical testing, protein adsorption, and swelling analyses. As a result, the mechanical strength, viscosity, swelling properties, and surface characteristics of the biomaterial were evaluated. SaOS-2 human osteosarcoma cell line was used for 3D bioprinting studies. Cell viability analyses were performed via Live/Dead and MTT assays. Mineralization was investigated and assay was carried out with Alizarin Red Staining. According to obtained results, P11-4/QSH/Gel scaffolds provide high cell viability and proliferation rate compared to pristine QSH and QSH/Gel control groups. Also, with the addition of P11-4 to QSH/Gel, a certain amount of increase in mineralization was observed after day 7 on long-term cultured scaffolds. As a result of this study, it was concluded that P11-4-based QSH/Gel has a high potential to be used as a bio-ink in the production of 3D scaffolds for dental tissue engineering applications.
  • Master Thesis
    Development and Characterization of Magnesium Alginate Hydrogels for 3d Cell Culture Formation
    (01. Izmir Institute of Technology, 2021) Çoban, Başak; Arslan Yıldız, Ahu
    Cell culture is an important tool for biological research. Two-dimensional (2D) cell culture is still used but growing cells on plastic surfaces offering unnatural growth kinetics and cell attachment. Three-dimensional (3D) cell culture allows cells to growth in their 3D physical shape and interact with their surroundings which represent the natural microenvironment. Hydrogels are crosslinked networks, have become increasingly used biomaterial for 3D cell culture with their ability to simulate the nature of most soft tissues. In this thesis, a new methodology based on bio-patterning was developed to fabricate (3D) cellular structures by using Mg-alginate hydrogel and fabricated 3D cellular structures was utilized for drug screening studies. Mg-alginate hydrogel has a specific gelation/de-gelation characteristics compared to other types of hydrogels due to its weak polymer-ion interaction. In this study slow gelation and de-gelation property of Mg-alginate hydrogel was used for biopatterning of 3D cellular structures. Plackett-Burman and Box-Behnken design models were used to optimize parameters of Mg alginate-based biopatterning method while using HeLa cells as a model cell line. Then, the applicability of newly developed methodology was successfully demonstrated by using SaOS-2 and SH-SY5Y cells to fabricate 3D cellular structures. Cell proliferation and migration profiles were observed during long-term culturing with time-dependent light microscopy images. Also cell proliferation and viability of long-term cultured tumor models were analyzed by using Alamar Blue and Live/Dead assays. Moreover, F-actin, Collagen I, and DAPI staining/immunostaining was done to investigate cellular and extracellular components of 3D cellular structures for short and long-term culture times. Finally, the dose-response of fabricated 3D structures was evaluated and compared with standard 2D cell culture by applying doxorubicin (DOX). The IC50 values were calculated for 3D cellular structure of HeLa, SaOS-2 and SH-SY5Y cells as 8.2, 7.8, and 2.1 µM respectively while IC50 values of 2D controls obtained as 3.2, 4.4, and 0.2 µM respectively. These results were also statistically analyzed and dose responses were found significantly different according to t-test, which means 3D cellular structures were more resistant to drug exposure compared to 2D cell culture.
  • Master Thesis
    Characterization and Utilization of Injectable Hydrogels for Tissue Engineering Applications
    (Izmir Institute of Technology, 2020) Güzelgülgen, Meltem; Arslan Yıldız, Ahu
    Tissue engineering combines the knowledge of the engineering aspects with life sciences to improve human health. Recent studies in tissue engineering have focused on investigating biocompatible scaffold materials and design. Quince seed hydrogel(QSH) has been used in traditional and modern medicine for skin wound and burn treatments, synovial lubrication, cough and asthma removal, and oral drug delivery with its antioxidant potential and biocompatible aspects. This thesis focuses on developing QSH and evaluating its potential as an injectable hydrogel in treating bone tissue defects as a totally new tissue scaffold and also as a promising tissue filling material. For this purpose, QSH scaffold optimization was carried out using various concentrations of hydrogel and crosslinkers which were glutaraldehyde(GTA) and 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide(EDC)/N-hydroxysuccinimide(NHS). Morphological and chemical analysis of QSH was done using SEM, FTIR, AFM, and protein adsorption test. Thus, porosity, swelling ratio, degradation rate and surface characteristics were evaluated. NIH-3T3 and SaOS-2 cell lines were utilized for 3D cell culture formation. Afterward, 3D spheroids were analyzed for cell viability and proliferation by using AlamarBlue and LiveDead assays, and also cell imaging technics. Results showed that QSH scaffolds did not show any cytotoxic effect on NIH-3T3 and SaOS-2 cells. The optimum results were achieved with 2mg/mL of QSH and 0.03M GTA concentrations; where 76.59µm average pore size, 56.8 fold water holding capacity and at least 80% cell viability was observed. Therefore, it was concluded that QSH has a high potential to promote tissue engineering applications with its injectable texture as a filling material.
  • Master Thesis
    Ultra-Porous Interconnected Hydrogel Structures for Tissue Engineering Applications
    (Izmir Institute of Technology, 2018) Yıldız, Büşra; Yıldız, Ümit Hakan; Arslan Yıldız, Ahu
    Tissue engineering aims to repair and regenerate tissue and organs with functional defects. The most significant developments in tissue engineering emerging as modification of the scaffold used to mimic native extracellular matrix (ECM) and support cell proliferation and differentiation. Hydrogel-based biomaterials are one of the most utilized materials as scaffold providing excellent chemical, physical/biophysical properties, high biocompatibility and functionality necessary for the applications in tissue engineering. In this study, Gelatin methacryloyl hydrogel (GelMA) and Gelatin-urethane hydrogels (GelatinK) are successfully synthesized as scaffold material for tissue engineering applications. Gelatin is modified with methacrylic anhydride for GelMA polymer and with 2-isocyanatoethly methacrylate for GelatinK polymer. The hydrogels of these two novel polymer are produced with photopolymerization reactions in aqueous media using Irgacure 2959 as redox initiator. Hydrogels are freeze-dried to remove solvent in the gel matrix and then they immersed in distilled water to reach equilibrium swelling ratio. The swelling capacity of GelMA hydrogels ranges between 1200 and 300% whereas GelatinK hydrogels has swelling capacity in between 1900-380%. Also, morphology of the hydrogels were investigated with Scanning Electron Microscopy (SEM). GelMA hydrogels has pore sizes between 142-14 µm while GelatinK hydrogels has between 160-56 µm pore sizes. The cell viability assay were also conducted using GelMA and GelatinK hydrogels. The results showed that both hydrogels provide high viability as compared to 2D control assay.
  • Master Thesis
    Polymer Based Extracellular Matrix Mimetics for 3d Cell Culture
    (Izmir Institute of Technology, 2018) Türker, Esra; Arslan Yıldız, Ahu
    Tissue engineering combines engineering principles and knowledge of life sciences to improve biological substituents. Three dimensional (3D) supporting structures, namely scaffolds obtained from biomaterials to mimic extracellular matrix (ECM) that provides suitable microenvironment for cell proliferation, migration and differentiation. In this study, poly (L-lactide-co-ε-caprolactone) (PLLCL) and collagen type I was used to fabricate scaffold by electrospinning method. In literature, collagen was often dissolved in toxic and harmful solvents that creates the major problem for cell culture applications. To overcome this problem “co-spinning” methodology is utilized for the formation of non-toxic collagen-based ECM mimetic scaffold. Collagen mixed with water-soluble carrier materials which is either polyvinylpyrrolidone (PVP) or polyvinyl alcohol (PVA) and co-electrospinning is carried out with PLLCL. Fabricated scaffolds were immersed into water to remove co-spinning agent; PVA or PVP, so only PLLCL/Collagen remained. PLLCL has homogeneous fibers in a diameter of 1.312 ± 0.22μm. The contact angle of PLLCL (136.6° ± 2.6) proved hydrophobic behavior of PLLCL material. The contact angle of the scaffold decreased up to 86.7° ± 0.1 confirming that hydrophobic behavior is decreased with the addition of collagen. Also, collagen-containing scaffolds were saturated at lower amount of protein than PLLCL, PLLCL/PVA and PLLCL/PVP scaffolds. Cytotoxicity analysis of scaffolds showed that PVA containing scaffolds had lower viability than PVP containing scaffolds; so most of the cell studies were carried out with PLLCL/ Collagen scaffolds fabricated by PVP cospinning. Cell proliferation on PLLCL/Collagen scaffolds found to be more favorable than PLLCL and PLLCL/PVP scaffolds.