Browsing by Author "Uz, Metin"

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Preparation and characterization of nanoparticles as carriers for gene delivery
(Izmir Institute of Technology, 2014-06) Uz, Metin; Altınkaya, Sacide
In the first part of this thesis, a comprehensive characterization of polyethylene glycol (PEG) modified AuNPs designed for imaging or diagnostic purposed was carried out to investigate the effect of the size, PEG layer conformation and grafting density on the cellular uptake, toxicity and cell cycle phases against prostate (PC3), colon (CaCo2) cancer cell lines and 3T3 Swiss fibroblast cells. It was noticed that the cellular uptake and toxicity profiles of the particles varied depending on the size, surface properties and cell type. The particles were found to show alterations in cell cycle phases by causing DNA damage without apoptotic behavior at certain doses. In the second part of this thesis, efficient multilayer small interfering RNA (siRNA) delivery systems based on gold nanoparticles (AuNPs), cationic pentablock copolymers or fusogenic peptides were developed using cleavable disulfide bonds and electrostatic interactions. siRNA/Polymer (polyplexes) and siRNA/Peptide (peptideplexes) complexes formed by direct electrostatic complexation between siRNA and the cationic pentablock copolymers or peptides were used as controls, respectively. In addition, a conjugate siRNA delivery system based on the cleavable disulfide bonds between siRNA and fusogenic peptide was also proposed as an alternative system. The siRNA activity, toxicity, cellular uptake and intracellular distribution of the developed systems were investigated against luciferase-expressing SKOV3 ovarian cancer cell line. The use of cationic block copolymers or fusogenic peptides in AuNP based multilayer systems and complex systems, provided efficient siRNA condensation and protection from nuclease enzyme and serum protein degradation, in addition to cellular uptake, endosomal escape and siRNA activity in the cytoplasm.
Preparation of controlled release antimicrobial food packaging materials
(Izmir Institute of Technology, 2009) Uz, Metin; Alsoy Altınkaya, Sacide
In this study, potassium sorbate (Psb) incorporated cellulose acetate (CA) films were developed for antimicrobial food packaging applications. The most significant characteristics of these films were their asymmetric porous structure. To achieve appropriate controlled release of Psb, the structure of the films were changed by manipulating the initial casting composition, wet casting thickness, drying temperature and number of layers. The effectiveness of the films was tested through measurement of release kinetics and antimicrobial activity on selected microorganism, Penicillium commune. It was found that as the initial casting composition, wet casting thickness and drying temperature increase, porosity and pore size of the films reduce leading to slower release rates. The most significant parameter affecting the release was found as the number of layers. The diffusion coefficient of Psb through multilayer films decreased by two orders of magnitude compared with single layer. Drying-induced crystallization was observed in single layer films. Higher number and larger size of crystals were observed in more porous films. Fast initial release of Psb from the single layer films which is controlled by Fickian diffusion was followed by a decreasing release rate due to slow crystal dissolution. However, in multilayer films, release rate is regulated onl by diffusion of Psb through the film. All the films prepared showed growth inhibition on P. commune. The antimicrobial activities of single layer films were found higher than the multilayer films. The results of this study demonstrated that Psb incorporated CA films show promising potential for controlled release in antimicrobial packaging.