Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Use of Snps With Controlled Size & Shape for Enhanced Surface Hydrophobicity & Hardness for Coil Coating Applications(01. Izmir Institute of Technology, 2023) Sulubaş, Şevval; Polat, Mehmet; Polat, HürriyetIncreasing the hardness of surface while improving hydrophobicity simultaneously has important implications in coating applications. The use of nano sized particles for this purpose is an interesting area of research. SNPs with mono and multi size distributions in a wide size range were successfully synthesized using the Stöber Method directly or after proper modifications such as utilizing seed particles as in Stöber growth solutions. The synthesized monosize and bi-modal silica particles were then employed in coating studies. The silica nanoparticles were added to a clear coat without pigments and fillers, followed by the introduction of a pigmented topcoat. The addition of 25% monosize silica nanoparticles led to a contact angle (CA) of 92°, while an equal amount of bi-modal silica particles increased the CA to 106°. Notably, the highest CA value of 116.7° was achieved with a 40% addition of bi-modal silica particles. When measured CA was converted to actual CA by incorporating the roughness parameter, the maximum effective CA was calculated as 140°. In terms of mechanical properties, loading monosize silica nanoparticles up to 35% resulted in a surface hardness of 2H. Further increasing the loading to 45% improved the surface hardness to 3H. While a 40% addition of monosize silica was necessary to achieve a pencil hardness of 3H, 20% addition of bi-modal sample was sufficient. The findings above demonstrate that addition of nanosized silica particles simultaneously improve hardness and surface hydrophobicity and that a bi-modal particle size distribution results in a superior performance compared to mono-modal particle size distribution.Master Thesis Development of Sub-Cellular Organelle Targeted Fluorescent Silica Nanoparticles(Izmir Institute of Technology, 2019) Yüksel, Almila; Özçelik, Serdar; Özçelik, SerdarSilica nanoparticles have been studied extensively in cellular applications due to their physicochemical properties. The surface of silica nanoparticles represent the key parameter in biological studies. Owing to their versatile surface chemistry, have ability to increase bioavailability and selectivity. Therefore, it is significant to understand how biomolecules interact with the surface of silica nanoparticles. The study reviews how synthesized both negative and positive potential silica nanoparticles and can transfer their properties to the cells. In the second part, our synthesized silica nanoparticles were characterized physicochemically using some instrumental devices. To answer the role of silica nanoparticles in the cells, some outcomes such as viability test, image analysis, colocalization analysis and mitochondrial membrane potential were investigated. A549 (adenocarcinomic human alveolar basal epithelial cells) and BEAS-2B (human bronchial epithelial cells) cell lines were selected in our studies. Our results showed the cytotoxicity was dose and time dependent in direct proportion. Mitochondrial accumulation were observed in cells treated with the silica nanoparticles according to Pearson’s Coefficient Correlation and Image J analysis. The study concluded that the silica nanoparticles can be used in the field of targeted delivery and bioimaging in cellular studies.Master Thesis Investigations on Surface Electric Charge of Silica Nanoparticles With Different Surface Roughnesses(Izmir Institute of Technology, 2019) Alan, Büşra Öykü; Barışık, MuratSilica nanoparticles have been receiving more attention from diverse research areas recently due to their significant physical properties such as large pore volume and high internal surface area, colloidal stability, high biocompatibility, and tunable pore sizes. These silica nanoparticles are great candidates for drug delivery applications because they can transport a large amount of drugs into selective organs and tissues due to their high surface area and large pore volume. However, there are important drug delivery mechanisms that need to be understood properly such as cellular uptake, endosomal escape, drug loading and release, and crossing physical barriers. Physicochemical properties of nanoparticles (size, shape, surface charge, or surface chemistry) are important for understanding these mechanisms in order to develop successful drug delivery applications. This research investigates how these surface charge properties change with different particle, pore diameters, roughness structure on the nanoparticle surface, and different temperature and solution conditions. Also, we investigate how the surface charging behavior of rough nanoparticles interacts with a flat plate. Rough nanoparticles and their interactions with surfaces theoretical assumptions can be wrong and ionic distribution can show variation locally. In order to calculate ionic distribution and surface charge properties in these systems, proper equations and boundary conditions were employed. The charge regulation model was used as a boundary condition because of the electric double layer overlap effect. Results showed that there was a considerable variation on surface charge properties due to the roughness structure with different roughness and particle sizes and temperature difference.