LEE- Nano Bilim ve Nano Mühendislik Lisansüstü Programı

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http://hdl.handle.net/11527/19415

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Konu "Biotechnology" ile LEE- Nano Bilim ve Nano Mühendislik Lisansüstü Programı'a göz atma
  • Öge
    Designing, developing and using the anode of a microbial fuel cell by containing PDMS,carbon nanotubes and graphene
    (Graduate School, 2022) Şakar, Elif Hazal ; Trabzon, Levent ; 713487 ; Nano Science& Nano Enginering Programme
    In the last few years, micro/nano electromechanical systems are an area that has been rising very rapidly and attracting a lot of attention of researchers. Microbial fuel cells, which is also a subject covered by the MEMS/NEMS field, is also a very interesting field of study. The reason for this is the increase in energy consumption in the world with each passing day and the search for a renewable energy source has become a necessity. The anodes and cathodes of MFCs are intended to operate at both low cost and high efficiency. Graphene, carbon nanotubes and PDMS, an organic polymer, can be counted among the materials that are widely used in this field and are trying to be developed. In our own study, we used these materials as hybrid nanocomposites. In addition to the MFC anode electrode studies in the literature, we tried to obtain electrical conductivity with lower cost and higher efficiency. In order to achieve these goals, we designed a special pattern in the anode electrode, which will increase the electrode surface area in a way that the microbial flora can be used most effectively, ensure the efficient adhesion of the microbial flora, and to attract electrons with the highest capacity, and we have produced it by photolithography. In order to find the optimum electrode, PDMS/MWCNT/GNP hybrid nanocomposite samples were produced at different ratios. In addition, the effect of treating the produced anode electrodes with sulfuric acid on the electrical conductivity was investigated. As a result of our production, we analyzed the anode electrodes with a few characterization devices that are widely used in nanotechnology studies. As a result of the analyzes made, it was observed that the produced electrodes had a very successful electrical conductivity when compared with the examples in the literature. It has been observed that the treatment with sulfuric acid causes a very successful increase in electrical conductivity within a certain treatment time. As an important result, it has been observed that the electrical conductivity can vary greatly depending on the mixing ratios and the type of nanofiller used. As a result of this experimental study, it has been concluded that the electrodes produced at low cost and at certain rates have successful electrical conductivity compared to previous studies in the literature.
  • Öge
    Development of microfluidic based single cell capturing systems for early detection of diseases
    (Fen Bilimleri Enstitüsü, 2020) Altınağaç, Emre ; Kızıl, Hüseyin ; 650348 ; Nanobilim ve Nanomühendislik Ana Bilim Dalı
    It is known that cancer cells in the bloodstream are quite low compared to other cells in the blood. Microfluidic based systems have been studied for diagnosis, follow-up of the disease and new drug tests to be performed on this disease. A microfluidic based system with two successive regions for separation and analysis has been developed. In the first region, the target cell type is differentiated from a complex mixture containing multiple cells by dielectrophoresis, which allows an insulating particle to be polarized under an electric field. Since different cell types can be polarized at different rates under the same electric field, this method allows the separation of the cells from each other under suitable conditions. In this study, a microfluidic system consists of two consecutive regions, namely the separation and analysis regions are demonstrated. In the first region, the target cell type is separated by dielectrophoresis from a complex cell mixture. The target cells collected in the first region are continuously transferred to the second region and are captured in a single cell array formation at the hydrodynamic capture stations placed on the measuring electrodes. Impedance analysis was performed to establish a platform for detection and drug screening. While both regions were integrated on a single chip in the final device, each region were examined separately during our study. The results of impedance analysis obtained from different cells based on different medium conductivities with a frequency range of 0.1kHz – 500kHz are presented here. We recorded impedance measurements at stations where cells were individually captured before and after cell entrapment. Experimental results are divided into cases where the conductivity of the medium is higher and lower than the cell conductance. Overall magnitude of impedance shift is significantly higher when the medium conductivity is lower than the cell conductance. When all results are evaluated, it can be seen that depending on the target cell type, an optimum medium conductivity and frequency range can be selected so as to obtain the measurement result with the highest sensitivity. A microfluidic cell culture platform, named as organ-on-a-chip in the literature, has been increasingly studied over the last few years to mimic tissue and organ-level physiology, containing a membrane with a continuous and porous structure inhabited by living cells, and with microfluidic channels to mimic the mechanical effects and to supply the necessary nutrients. These platforms create tissue and organ environments that are not possible with traditional 2D or 3D culture systems, and enable real time imaging and analysis of biochemical, genetic and metabolic activities of living cells. In this project, present fabrication techniques of microfluidic devices are used for the fabrication of organ-on-a-chip platforms. The tissue structure was imitated by coating a single-layer cell on the upper and lower sides of the membrane in the structures of the renal chip tubules and lung alveoli on organ-on-a-chip platforms. The cell viability was characterized by MTT test and the cell viability was maintained by providing oxygen, carbon dioxide and nutrient exchange under incubation conditions by means of nutrient medium flow provided into the upper and lower channels, and the barrier property of the cell tissue was measured by electrical resistance (TEER) measurements. The viability of the renal tubules cultured in the microfluidic system between 0-48 hours was recorded by MTT assay. TEER results showed that the tight-junctions of cell tissue were different under static and dynamic conditions in the kidney-on-chip systems. The results obtained by MTT test to measure cell viability were in agreement with TEER and the viability of kidney cells was higher in 48 hours under dynamic conditions compared to static conditions. With the successful culturing of two different cell types under static conditions in lung-on-chip systems, their viability and cell barrier resistance values were recorded by TEER measurement for 0-48 hours. The results obtained by MTT test and TEER measurements showed that lung cells under shear stress and mechanical stress had higher viability than cells under static conditions.