Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Development of Plasmonic Nanostructures for Photothermal Therapy of Prostate and Breast Cancer(Izmir Institute of Technology, 2019) Tomak, Aysel; Bulmuş, Volga; Şahin, HasanThe aim of this thesis is to synthesize gold nanorods (AuNRs) and lipid-stabilized nanobubbles containing AuNRs and investigate the potential of these plasmonic nanostructures as photothermal therapy agents for breast and prostate cancer through in vitro cell culture experiments. For this aim, firstly, AuNRs were synthesized at varying aspect ratios (ARs) and characterized via several techniques including UV-Vis/NIR spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), inductively coupled plasma-mass spectroscopy (ICP-MS), electrophoretic light scattering (ELS) and X-ray photoelectron spectroscopy (XPS). The surface of AuNRs was modified with a biocompatible polymer, poly(ethylene glycol) (PEG), via ligand exchange method. Cytotoxicity, cell uptake and photothermal effects of AuNRs were investigated via in vitro cell culture experiments using human prostate cancer (DU 145) and epithelial (RWPE-1), breast cancer (MCF7) and epithelial (MCF 10A) cell lines. It was concluded that AuNRs (AR=4.0) were superior than AuNRs (AR=7.0) in terms of cell viability and photothermal effect. Separately, a non-commercial antibody (Ab) targeting a specific sialic acid derivative on the plasma membrane of DU 145 and MCF7 cancer cells was conjugated to AuNRs. Conjugations were characterized with the same techniques and investigated via in vitro cytotoxicity and cell uptake experiments. The Ab-conjugated AuNRs displayed the capability of selective targeting prostate cancer cells. Additionally, lipid-stabilized AuNRs and lipid-stabilized nanobubbles containing AuNRs (AuNBs) were synthesized for the first time and characterized using UV-Vis/NIR spectroscopy, SEM, ICP-MS and ELS techniques. Lipid-stabilized AuNRs were successfully synthesized using varying lipid mixtures instead of cationic, toxic surfactant. Separately, AuNBs were synthesized by combining PEG modified AuNRs with DPPC: DSPE-PEG lipid film under sonication and gas stream. AuNBs showed the same or significantly lower toxicity depending on the cell types and the same photothermal effect with respect to AuNRs (AR=4.0) upon irradiation under laser at 808 nm.Doctoral Thesis Nanosized zing borate production(Izmir Institute of Technology, 2009) Gönen, Mehmet; Balköse, DevrimThe present study covers both zinc borate synthesis from boric acid-zinc oxide and borax decahydrate-zinc nitrate hexahydrate pairs; treatment of those samples by supercritical carbon dioxide drying, supercritical ethanol drying, and freeze drying techniques to obtain nanosized products. Zinc borate samples before and after supercritical drying were characterized by analytical titration, SEM, XRD, TGA, DSC, FTIR, and N2 adsorption at 77 K.The use of oleic acid as a modifying agent, ultrasonic treatment and nanosized zinc oxide in the reaction of zinc oxide and boric acid did not make significant effect in controlling the particle size. However, particle size of zinc borate produced from borax and zinc nitrate has increased with reaction time. Interaction of zinc borates with CO2 or ethanol at supercritical conditions or compression of crystals by high pressure created by the expansion of water during freezing are possible side effects of the nanoparticle producing processes. Zinc borate (2ZnO.3B2O3.7H2O) having water of crystallization in its structure reacted partially with CO2 to produce zinc carbonate, however zinc borate (2ZnO.3B2O3.3H2O) containing only hydroxyl groups did not react with CO2 in supercritical CO2 drying. While zinc borate (2ZnO.3B2O3.3H2O) decomposed partially and formed anhydrous zinc borate and zinc oxide, zinc borate (ZnO.B2O3.2H2O) decomposed completely and formed only zinc oxide in the supercritical ethanol drying that was carried out at 6.5 MPa and 250aC. Boric acid formed from the decomposition of both zinc borates was separated by ethanol extraction. If the initial particle size of zinc borate sample was at nano level, it would be possible to obtain nano particles by freeze drying.Doctoral Thesis Synthesis and Control of Exciton Dynamics in Cdte, Cdte/Cds and Znxcd1-Xte Colloidal Nanocrystals(İzmir Institute of Technology, 2012) Eral Doğan, Leyla; Özçelik, SerdarThe aim of this study is to synthesize cadmium-based semiconductor colloidal nanocrystals and to control their exciton dynamics by tuning the size and composition of the nanocrystals (NCs). CdTe, CdTe/CdS binary, and ZnxCd1-xTe ternary semiconductor NCs are prepared by wet chemistry. The reactions are thoroughly optimized to enhance the optical properties. The optical properties of CdTe and CdTe/CdS are tuned by the size of the NCs by adjusting the reaction (the growth) time. Coating CdTe NCs with CdS layer enhances the photoluminescence quantum yields up to 45%. ZnxCd1-xTe ternary nanoalloys were synthesized by varying the initial mole ratios of metals (Zn/Zn+Cd) and the growth time. The size and the composition-tunable ZnxCd1-xTe nanoalloys exhibit highly luminescent optical properties. When the amount of initial Zn precursor is low, the nanoalloys have Cd-rich and Zn-poor internal crystal structure. However, at higher amount of Zn precursor, the nanoalloys have Zn-rich and Cd-poor core exhibiting gradient composition. The exciton interactions and dynamics are investigated as a function of the size of CdTe/CdS, and the composition and the size of ZnxCd1-xTe nanoalloys. The exciton interaction yields amplification in the output signal at the threshold of 1015 photon/cm2s per laser pulse. The exciton lifetimes are in the range of picoseconds to nanoseconds. The decay associated spectra are affected by the laser power, size and composition of the NCs. As the laser power increases new excitonic states are created especially in ZnxCd1-xTe nanoalloys. Multiexcitons were created in the NCs depending on the laser power. Small NCs exhibit stronger exciton-exciton interactions under high laser power compared to larger NCs. However larger NCs have lesser exciton density, therefore reducing the exciton-exciton interactions.