1. Protein adsorption on various plasma-treated polyethylene-terephthalate substratesNina Recek, Morana Jaganjac, Metod Kolar, Lidija Milković, Miran Mozetič, Karin Stana-Kleinschek, Alenka Vesel, 2013, original scientific article Abstract: Protein adhesion and cell response to plasma-treated polymer surfaces were studied. The polymer polyethylene terephthalate (PET) was treated in either an oxygen plasma to make the surface hydrophilic, or a tetrafluoromethane CF4 plasma to make the surface hydrophobic. The plasma source was radiofrequency (RF) discharge. The adsorption of albumin and other proteins from a cell-culture medium onto these surfaces was studied using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The cellular response to plasma-treated surfaces was studied as well using an MTT assay and scanning electron microscopy (SEM). The fastest adsorption rate was found on the hydrophilic oxygen plasma-treated sample, and the lowest was found on the pristine untreated sample. Additionally, the amount of adsorbed proteins was higher for the oxygen-plasma-treated surface, and the adsorbed layer was more viscoelastic. In addition, cell adhesion studies support this finding because the best cell adhesion was observed on oxygen-plasma-treated substrates.
Keywords: oxygen and fluorine plasma treatment, polymer surface modification, protein adsorption, cell adhesion, quartz crystal microbalance, QCM
Published in DKUM: 22.06.2017; Views: 707; Downloads: 327
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2. Covalent binding of heparin to functionalized PET materials for improved haemocompatibilityMetod Kolar, Miran Mozetič, Karin Stana-Kleinschek, Mirjam Fröhlich, Boris Turk, Alenka Vesel, 2015, original scientific article Abstract: The hemocompatibility of vascular grafts made from poly(ethylene terephthalate) (PET) is insufficient due to the rapid adhesion and activation of blood platelets that occur upon incubation with whole blood. PET polymer was treated with NHx radicals created by passing ammonia through gaseous plasma formed by a microwave discharge, which allowed for functionalization with amino groups. X-ray photoelectron spectroscopy characterization using derivatization with 4-chlorobenzaldehyde indicated that approximately 4% of the –NH2 groups were associated with the PET surface after treatment with the gaseous radicals. The functionalized polymers were coated with an ultra-thin layer of heparin and incubated with fresh blood. The free-hemoglobin technique, which is based on the haemolysis of erythrocytes, indicated improved hemocompatibility, which was confirmed by imaging the samples using confocal optical microscopy. A significant decrease in number of adhered platelets was observed on such samples. Proliferation of both human umbilical vein endothelial cells and human microvascular endothelial cells was enhanced on treated polymers, especially after a few hours of cell seeding. Thus, the technique represents a promising substitute for wet-chemical modification of PET materials prior to coating with heparin.
Keywords: poly(ethylene terephthalate), vascular graft, biocompatibility, heparin, plasma, functionalization, haemolysis, platelet adhesion, endothelization
Published in DKUM: 21.06.2017; Views: 741; Downloads: 295
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3. Synthesis of micro-composite beads with magnetic nano-particles embedded in porous CaCO[sub]3 matrixAlenka Vesel, Aljoša Košak, David Haložan, Kristina Eleršič, 2012, original scientific article Abstract: A method for synthesis of soft magnetic microbeads is presented. The microbeads are made from magnetic nanoparticles dispersed in CaCO3 (calcium carbonate) matrix. The composite beads are almost perfectly spherical with a diameter of few micrometers. The majority of the composite beads consists of a porous CaCO3 matrix. Magnetic nanoparticles with a size of about 10-15 nm are made of Fe2O3. They are captured inside the pores of CaCO3 matrix during its formation. CaCO3 matrix is formed by crystallization from saturated solution of sodium carbonate and calcium chloride. The composite beads are coated with a layer of functionalized polymer. The magnetic microbeads were characterized by SEM and XPS. Different functional groups were detected by XPS measurements including SO3–,NH3+,NH2,CO32– and OH groups. The results indicate that the iron oxide particles are absent on the surface and that the polymer coating serves as a good biocompatible film.
Keywords: composite, surface characterization, XPS, functionalization, Fe nanoparticles, microbeads
Published in DKUM: 23.03.2017; Views: 801; Downloads: 81
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4. Polymer characterization with the atomic force microscopeUroš Maver, Tina Maver, Zdenka Peršin, Miran Mozetič, Alenka Vesel, Miran Gaberšček, Karin Stana-Kleinschek, 2013, independent scientific component part or a chapter in a monograph Keywords: atomic force microscope, polymer characterization, polymer molecules
Published in DKUM: 10.07.2015; Views: 1108; Downloads: 83
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5. Razvoj naprednih procesov za doseganje visoko učinkovitih nano modificiranih tekstilnih materialov : zaključno poročilo ARRS projekta: L2-4101Karin Stana-Kleinschek, Darinka Fakin, Alenka Ojstršek, Manja Kurečič, Silvo Hribernik, Rupert Kargl, Majda Sfiligoj-Smole, Lidija Fras Zemljič, Zdenka Peršin, Tanja Kos, Miran Mozetič, Alenka Vesel, Vladimir Vrečko, Denis Jahič, Nika Veronovski, 2015, final research report Keywords: tekstilni materiali, nanotehnologija, modifikacija vlaken
Published in DKUM: 15.06.2015; Views: 1639; Downloads: 64
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