Master Degree / Yüksek Lisans Tezleri

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

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Author: search.filters.author.Tekin, Hüseyin CumhurSubject: search.filters.subject.Microfluidic devices

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Now showing 1 - 3 of 3
  • Master Thesis
    Magnetic Based Cell Sorting in Microfluidic Devices
    (01. Izmir Institute of Technology, 2024) Özcan, Hatice Ahsen; Tekin, Hüseyin Cumhur; Tekin, Hüseyin Cumhur; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Kan, hastalıkla ilişkili hücreleri heterojen örneklerden ayırarak hastalık teşhisi ve tedavisi için kullanılır. Bu hücrelerin bazıları, örneğin damar hasarı ve kanser için biyobelirteçler olarak kullanılan dolaşımdaki endotel hücreleri (CEC'ler) gibi nadirdir. Bu nadir hücrelerin kesin olarak ayrılması çok önemli ve zordur. Bu sorunu çözmek için etiketsiz bir mikroakışkan sistem geliştirildi. Bu sistem, parçacıkları etiketlemeden belirli konumlara kaldırmak için manyetik, yerçekimsel ve sürükleme kuvvetlerinden yararlanan Manyetik Levitasyon ilkelerini kullanarak CEC'leri beyaz kan hücrelerinden (WBC'ler) izole eder. Mikroakışkan çipin bir girişi ve iki çıkışı vardır: üst çıkış, CEC'lerin bir taklidi olarak düşük yoğunluklu İnsan Göbek Ven Endotel Hücrelerini (HUVEC'ler) toplarken, alt çıkış, bir geri çekme yöntemi kullanarak WBC'lerin bir taklidi olarak yüksek yoğunluklu U937 hücrelerini toplar. Ayrıştırma verimliliğini optimize etmek için paramanyetik ortam olarak kullanılan gadolinyumunun (Gd3+) çeşitli konsantrasyonları, akış hızları ve oranları test edildi. Çıkışlar arasındaki akış hızı oranlarının ayarlanması, sanal bir ayraç oluşturarak ayıklama verimliliğini artırdı. Toplam 0,2 mL/saat geri çekme akış hızıyla 30 mM Gd3+ kullanılması, üst çıkıştan HUVEC'lerin %86,67 ± 10,4'te ve U937 hücrelerinin %20,83 ± 7,93'te ayrıştırma verimliliğine ulaştı. Ek olarak, aynı mikroakışkan çip kullanılarak canlı/ölü MDA-MB-231 kanser hücresi ayrımı gerçekleştirildi. Canlı/ölü ayırmanın amacı, daha fazla sayıda canlı hücrenin sferoid oluşum verimliliğini arttırması nedeniyle, sferoid oluşum gibi doku mühendisliği uygulamalarında kullanılmak üzere canlı hücreler elde etmekti. Toplam 0,25 mL/saat geri çekme akış hızıyla 75 mM Gd3+ kullanılması, üst çıkıştan canlı hücrelerin %86,03 ± 2,54'te ve ölü hücrelerin %11,02 ± 5,81 oranında ayrıştırma verimliliğine ulaştı.
  • Master Thesis
    Development of Microfluidic Devices for Investigating Small Molecule Induced Chemotaxis of Dendritic Cells
    (01. Izmir Institute of Technology, 2023) Tekin, Hüseyin Cumhur; Bedir, Erdal; Bedir, Erdal; Tekin, Hüseyin Cumhur; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Microfluidics is the core branch of science and technology in which interdisciplinary research is conducted with a low amount of samples in microchannels ranging from 10-100 μm. The main objective of this thesis is to design and fabricate a chemotaxis microfluidic device (CMD) from the poly-methyl methacrylate (PMMA) substrate to analyze the immune cell behavior against cancer cells. The patterns of the three-layered CMD were generated using laser ablation. During the fabrication, Power (P) and Speed (S) values were varied to determine the optimal P-S combination. Then, the structural properties of microfluidic channels in the CMD were examined via microscope. The mechanical properties and liquid handling abilities of CMDs were also investigated through tensile and leakage tests, respectively. Moreover, cell viability of DC2.4 dendritic cells (DCs) and B16-F10 murine melanoma (B16-F10) cells in CMDs sterilized through either autoclaving or UV treatment were determined to test the suitability of CMDs via Live/Dead Assay. The highest cell viability for DCs and B16-F10 was obtained in autoclaved CMDs. For the maturation of DCs before seeding into CMD, DCs were stimulated with lipopolysaccharide (LPS) and Astragaloside VII (AST-VII) at various concentrations. While the cytotoxicity of LPS and AST-VII were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, the expression levels of specific chemokine receptors were also analyzed through flow cytometry. Lastly, stimulated DCs and B16-F10 were simultaneously cultured in the CMD, and the migratory behavior of DCs against B16-F10 was time-dependently studied. Consequently, CMD that provided cost-effective and rapid analysis of intercellular interactions was successfully developed.
  • Master Thesis
    Fabrication of Microfluidic Devices Via 3d Printer
    (Izmir Institute of Technology, 2019) Keçili, Seren; Bulmuş Zareie, Volga; Tekin, Hüseyin Cumhur; Tekin, Hüseyin Cumhur; Bulmuş, Volga; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The purpose of this thesis is to provide easy and rapid prototyping of microfluidic devices using 3D printing technology that overcomes disadvantages of traditional fabrication techniques and also enhanced optical transparency of 3D-printed microfluidic devices fabricated using new bonding strategies. For performance analysis of 3D printer, microfluidic channels and molds having different shape and dimensions were designed and fabricated. After the fabrication process, designed and fabricated channel dimensions were compared. Structures having at least having 50 μm feature were printed successfully. For enhancing transparency of fabricated 3D structures, two different fabrication techniques were developed. In these techniques, 3D structures were bonded on glass substrates with poly (dimethylsiloxane) (PDMS) and Formlabs Clear Resin interlayers. After 3D-printed structures were put on interlayers coated glass slides, they were either remained on coated slides or transferred on new slides. Bonding between 3D structures and glass slides were provided with UV exposure for resin and with elevated temperature for PDMS interlayers. Bonding strength of fabricated channels was investigated for different thicknesses of PDMS and resin interlayers. The bright-field and fluorescence imaging properties of these channels were also analyzed. Proposed fabrication technique showed 2-fold improved bonding strength and comparable bright-field and fluorescence imaging capability with respect to traditional plasma activated PDMS-glass bonding. Furthermore, protein modified glass substrates can be integrated in 3D-printed channels using the presented fabrication technique without disturbing protein functionality. Finally, in order to design a 3D-printed micropump having membranes that can be activated with compressed air, membrane deformation was characterized with different dimension.