Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Cell Separation in Microfluidic Devices(01. Izmir Institute of Technology, 2022) Öksüz, Cemre; Tekin, Hüseyin CumhurCell separation is used to separate homogeneous and individual cell classes from a heterogeneous cell population. The efficiency and purity of these separated cells are of great importance in personalized medicine, regenerative medicine, disease monitoring and drug testing as well as in the therapeutic and diagnostic research. In this thesis, different microfluidic approaches were presented for cell separation. With this regard, a closed channel vacuum-integrated microfluidic chip was developed using an air permeability of a Polydimethylsiloxane and density-based separation of microparticles was performed. Besides, a centrifugal microfluidic system, Spinochip, was developed with one reservoir as inlet and outlet for the first time and different fluid manipulations were shown in the system. The system was applied to clinical tests of hematocrit measurements and white blood cell estimation using real patient samples. The developed system offered correlated results with clinical results. In addition to closed channel microfluidics, negative-magnetophoresis microfluidic chip was demonstrated for the size-based separation of microparticles and cells. In this regard, capturing rate of breast cancer cells (MCF-7) and human monocyte cells (U937) was investigated. The results showed that the approaches presented here could promote to the microfluidic studies for size-based cell separation.Master Thesis Magnetic-Based Cell Manipulation in Microfluidic Devices(01. Izmir Institute of Technology, 2022) Özçelik, Özge Solmaz; Tekin, Hüseyin CumhurCell manipulation is the concept of altering cell movement. Different manipulation techniques have been demonstrated with microfluidic systems for various studies such as tissue engineering, circulating tumor cell (CTC) filtering, and other biomedical applications. For instance, cell patterning and filtering studies are being developed through different manipulation approaches in microfluidic platforms where one of these approaches is the magnetophoresis principle method. Positive and negative magnetophoresis can be utilized generally through labeling or non-labeling, respectively. In this thesis, two different cell manipulation platforms using negative magnetophoresis were developed for cell patterning and cell filtration applications. These platforms allow several advantages such as simple fabrication, easy control, and low cost. Compared to other devices, the developed microfluidic platforms do not require any labeling process for cells for magnetic manipulation. In the patterning platform, microparticle and cell patterns were formed inside a simple microfluidic channel with different tilted angles in <1.5 hours. Furthermore, in the filtration platform, large microparticles were separated from small microparticles with 98.25% trapping efficiency. Live/dead cell separation of human monocyte macrophage cells (U937) under different flow rates was also investigated. The suggested platforms could be useful for label-free magnetic cell patterning and filtering in biomedical applications.Master Thesis Quantitative Phase Analysis in Lensless Digital Inline Holographic Microscopy(01. Izmir Institute of Technology, 2021) Demir, Ali Aslan; Tekin, Hüseyin Cumhur; Varlıklı, CananComputational imaging modalities replace the bulky, complex, and expensive optical components of traditional imaging procedures with numerical reconstruction steps. Digital holographic microscopy is one of the most prominent ones with the possibility of obtaining quantitative phase information by measuring the phase shift change caused by the refractive index of objects. In the lensless digital holographic microscopy system, a pinhole and a light-emitting diode are sufficient to create a holographic pattern on the camera sensor. Here, the optimization of a digital lensless inline holographic microscopy setup was performed to obtain optimal phase value. Also, to retrieve the lost phase information during the recording step, the numerical solution was performed with the single and multi-shot phase retrieval methods. Then, human breast adenocarcinoma (MDA-MB-231) and human myeloid leukemia (U937) cells were analyzed to obtain phase shift, perimeter, and circularity values. These parameters were used to obtain a quantitative differentiation model to replace the traditional labeling or visual confirmation steps with a direct analysis manner. The analysis of respective cells with the classification, object detection, and conditional generative adversarial models can be used directly with pre-trained weights to lessen the computational workloads. With this study, the quantitative analysis with lensless holographic microscopy setup was shown to be a label-free differentiation mechanism to separate cancer cells from monocytes cells which could be used for the early diagnosis of cancer. Also, the proposed method has the potential to be used to identify other cells with links to the diagnosis of different diseases.