Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
9 results
Search Results
Master Thesis Development and Characterization of Surface-Modified Emulsion Templated Scaffolds for Tissue Engineering Applications(01. Izmir Institute of Technology, 2024) Kocagöz, Mehmet; Dikici, Betül Aldemir; Zareıe, Esma Volga BulmuşEmülsiyon şablonlama, yüksek ve açık gözeneklilik sağlayan avantajlı bir iskele üretim yöntemidir. Bu yöntemde hidrofobik polimerlerin su ile karıştırılmasıyla yağ içerisinde su (w/o) emülsiyonları elde edilir. İç faz hacmi %74'ün üzerinde olan polimerize emülsiyonlar, yüksek iç fazlı emülsiyonlar (PolyHIPE'ler) olarak adlandırılır. Polikaprolakton, doku mühendisliğinde yaygın olarak kullanılan sentetik, biyolojik olarak bozunabilen ve biyouyumlu bir polimerdir, ancak malzemenin hidrofobik karakteri hücre-materyal etkileşimlerini sınırlamaktadır. Bu nedenle, bu çalışma kapsamında, emülsiyon şablonlama yöntemi ile üretilmiş, polikaprolakton tetrametakrilat (4PCLMA) esaslı iskelelerin biyolojik performanslarını artırmak için iskelelerin alkali muamelesi ve elde edilen iskelelerin karakterize edilmesi amaçlanmıştır. İlk olarak halka açma polimerizasyonu ile 4PCLMA pre-polimeri sentezlenmiş ve metakrilat grupları ile fonksiyon kazandırılmıştır. 4PCLMA ~%97 metakrilasyon derecesi ile başarıyla sentezlenmiş, 4PCLMA esaslı PolyHIPE'ler emülsiyon şablonlama yöntemi ile üretilmiş, üç farklı konsantrasyonda ve inkübasyon süresinde sodyum hidroksit (NaOH) ile muamele edilmiştir. NaOH işleminin iskelelerin morfolojileri, kütle kaybı, su tutma kapasitesi, mekanik özellikleri, yüzey alanı, hidrofilisitesi ve biyolojik performansı üzerindeki etkileri araştırılmıştır. NaOH uygulamasının iskelelerin ağırlığını ve mekanik mukavemetini azalttığı ancak aynı zamanda iskelelerin su tutma kapasitesini, hidrofilisitesini, yüzey alanını ve protein adsorpsiyon kapasitesini artırdığı görülmüştür. NaOH işleminden sonra PolyHIPE'lerdeki kimyasal değişiklikler spektroskopi ile doğrulanmıştır. In vitro sonuçlar, NaOH uygulamasının L929 hücreleri üzerinde sitotoksisiteye neden olmadığını ve Saos-2 hücrelerinin tutunma ve çoğalma davranışını olumlu yönde etkilediğini göstermiştir. Bu çalışma sonucunda NaOH muamelesinin, emülsiyon şablonlama ile üretilmiş doku iskelelerinin hidrofilisitesini ve biyolojik performansını artırmak adına alternatif bir yüzey modifikasyon yöntemi olarak kullanılabileceği gösterilmiştir.Master Thesis Development of a Natural Tubular Scaffold From Decellularized Parsley Stems To Be Used in Vascular Tissue Engineering Applications(01. Izmir Institute of Technology, 2024) Çevik, Merve; Dikici, Serkan; Özçivici, EnginCardiovascular diseases (CVD) are usually associated with narrowing or blockage of blood vessels and are the leading cause of death globally. By 2030, the annual incidence of CVD-related deaths is estimated to increase 23.3 million. Considering the advancements in endovascular surgery, the use of vascular grafts in cardiovascular surgery is becoming increasingly common. Autografts are the gold standard but have limitations, including limited tissue availability and complications from vessel isolation. Recently, synthetic grafts have emerged as alternatives, though they often fail due to thrombosis, atherosclerosis, intimal hyperplasia, or infection. Thrombosis, the main cause of post-implantation failure, is associated with damage or absence of the endothelial cell lining on the luminal surface of the vascular graft. To overcome the limitations mentioned so far, tissue-engineered vascular grafts (TEVG) have come into prominence. The use of decellularized plant tissues in tissue engineering applications has recently gained great importance. Accordingly, in this study, we fabricated tubular scaffolds from decellularized parsley stems and evaluated them in vitro as potential TEVGs. Our results demonstrated that native plant DNA was successfully removed, and biocompatible tubular biomaterials were successfully fabricated via chemical decellularization of parsley stems. The decellularized parsley stems showed suitable mechanical and biological properties for use as TEVG material. Finally, they were found to provide a convenient environment to form a pseudo-endothelium by recellularization with human endothelial cells prior to implantation. This study is the pioneer in the literature that reports on the potential of parsley stems to be used as a potential TEVG biomaterial.Master Thesis Preparation and Characterization of Poly-L Lactide-Natural Silica Composites(2023) Şirvanlıoğlu, Berna; Tıhmınlıoğlu, FundaTissue engineering research has been primarily focused on the development of customizable 3D scaffolds capable of promoting natural tissue regeneration while providing robust structural support. Synthetic polymer-based composites have garnered significant attention in recent years for biocompatibility and biodegradability, particularly in hard tissue engineering. In this study, we have chosen to combine the synthetic polymer PLA with natural silica as Diatomaceous earth for creating a customizable biomaterial tailored for bone tissue engineering applications. To create the PLA-Diatom composites, we employed melt mixing and hot-press methods, using two different types of diatoms: calcinated and raw diatoms. To enhance the compatibility of PLA, PEG and PEG/POSS were introduced as plasticizers/compatibilizers. Various concentrations of these plasticizers and reinforcing agents were meticulously applied to the PLA matrix to fine-tune the properties of the PLA biomaterial. Our comprehensive characterization involved SEM for morphology, mechanical testing, rheological analysis, AFM for roughness, contact angle analysis for surface wettability, swelling property, and FTIR for chemical structure. Our findings revealed that 3% diatom addition into PLA significantly improved tensile strength (32,72±0,27 for PLA and 51,51±4,15 for calcinated to 55,33±0,97 MPa for raw diatom), slight decrease in modulus (2277±45,65 for PLA to 2183,11 MPa for calcinated and 2246,43±24,19 for raw diatom), and reduced strain with higher diatom concentrations. Rheological analysis indicated a shift towards more liquid-like behaviour in PLA-Diatom composites, further enhanced by plasticizers, ensuring stable viscosities. Surface roughness increased with pure and plasticized PLA with diatom application. Surface wettability and water uptake capacity improved significantly compared to pure PLAMaster Thesis Development and Characterization of Biomimetic Peptide-Based Bioink for Dental Tissue Engineering(01. Izmir Institute of Technology, 2023) Altan, Zeynep; Arslan Yıldız, AhuRecently, 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, AhuCell 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 Cell Patterning With Magnetic Manipulation(01. Izmir Institute of Technology, 2020) Çağan, Melike; Özçivici, EnginTissue engineering is a biomedical engineering field that provides solutions to restore, maintain, improve or replace tissues or whole organs. The main goal tissue engineering is to overcome the restrictions of existing treatments that are based on organ transplantation. Cells and biomaterials can be used to form functional tissues and organs. Actually, the goal is to produce structures that resemble and mimic the real tissues. One of the useful mimicking technique is cell patterning. Cell patterning is a technique that provides cell clusters are located at a proper position for function of tissues. Some of the patterning techniques uses cell adhesion ligands, optical tweezers, acoustic tweezers, dielectrophoresis and magnetic force. In addition to the advantages of all these techniques, there are also disadvantages. However, Magnetic force-based cell patterning techniques provide excellent advantages such as low adverse effects to cell. Magnetophoresis is one of the magnetic force-based cell patterning technique that forms cell patterns without labeling cells in a short time using the principle of movement of the cells to lower magnetic field region in a paramagnetic medium. In this study, a cell patterning system was used to form cell patterns via magnetophoresis. Results showed that cell patterns were formed in different shapes in a short time and they maintained integrity even if magnetic force was removed.Master Thesis Characterization and Utilization of Injectable Hydrogels for Tissue Engineering Applications(Izmir Institute of Technology, 2020) Güzelgülgen, Meltem; Arslan Yıldız, AhuTissue 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, AhuTissue 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, AhuTissue 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.