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Now showing items 1 - 16 of 28

  • METHOD OF GROWING CARBON NANOWALLS ON A SUBSTRATE

    A method for growing carbon nanowalls on a substrate of an implantable medical device by means of a processing chamber is provided, said method comprising: providing said substrate in said processing chamber, evacuating said processing chamber to a processing pressure, entering a gas mixture inside the processing chamber, providing radicals inside said chamber and adsorbing said radicals on said substrate leading to growing of carbon nanowalls on said substrate.
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  • Polysaccharide Based Wound Care Materials

    Maver, Tina   Maver, Uros   Pivec, Tanja   Kurecic, Manja   Persin, Zdenka   Kleinschek, Karin Stana  

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  • Emerging Techniques in the Preparation of Wound Care Products

    Maver, Tina   Maver, Uros   Pivec, Tanja   Kurecic, Manja   Persin, Zdenka   Kleinschek, Karin Stana  

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  • Advanced Wound Care

    Maver, Tina   Maver, Uros   Pivec, Tanja   Kurecic, Manja   Persin, Zdenka   Kleinschek, Karin Stana  

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  • Bio-nanofibrous mats as potential delivering systems of natural substances

    Persin, Zdenka   Ravber, Matej   Kleinschek, Karin Stana   Knez, Zeljko   Skerget, Mojca   Kurecic, Manja  

    Considering the increasing resistance of numerous bacteria to antibiotics, a novel wound dressing material was developed with naturally acquired olive leaf extract, which shows not only good antimicrobial activity, but also very good antioxidant activity. Besides that, the leaves are treated as waste in agriculture, giving an impact on waste management. An environmentally friendly procedure, electrospinning, was used for the first time to prepare polysaccharide nanofibrous mats with incorporated olive leaf extract, with the unique property of releasing the active phenolic components in a prolonged manner over 24 hours. The developed electrospun mats were characterized using scanning electron microscopy, high-performance liquid chromatography and ultraviolet-visible spectroscopy for determination of free radical scavenging activity by 2,2-diphenyl-1-picrylhydrazyl, antimicrobial testing and release kinetics. Antimicrobial tests have shown that electrospun mats with olive leaf extract achieve reduction towards the tested microorganisms: Staphylococcus aureus (G+), Escherichia coli (G-), Enterococcus faecalis (G+) and Pseudomonas aeruginosa (G-), while the high antioxidant activity of olive leaf extract was preserved during the electrospinning procedure. Release of olive leaf extract from electrospun mats was mathematically modeled, and the release kinetics evaluation indicates the appropriateness of the Korsmeyer-Peppas model for fitting the obtained results of release ability due to erosion of polysaccharide nanofiber mats.
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  • Cellulose thin films from ionic liquid solutions

    Kargl, Rupert   Mohan, Tamilselvan   Ribitsch, Volker   Saake, Bodo   Puls, Juergen   Kleinschek, Karin Stana  

    The solution properties of cellulose, dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc), were analysed using rheology and turbidity measurements. The influence of dimethylsulfoxide addition and temperature change on the viscosity of these solutions was studied in detail. Subsequently, crystallinity measurements of precipitated powders from EMIMAc solutions were conducted. Additionally, the stability of cellulose during storage in the ionic liquid solution was proven by molecular weight analysis. Thin films of cellulose were prepared by spin coating from EMIMAc/DMSO mixtures and subsequent precipitation on silicon wafers and quartz crystal microbalance gold coated sensors. Atomic force microscopy and profilometry gave insights into the morphology and thickness of the prepared films and their possible application in the study of surface properties of cellulose.
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  • Advanced therapies of skin injuries.

    Maver, Tina   Maver, Uros   Kleinschek, Karin Stana   Rascan, Irena Mlinaric   Smrke, Dragica Maja  

    The loss of tissue is still one of the most challenging problems in healthcare. Efficient laboratory expansion of skin tissue to reproduce the skins barrier function can make the difference between life and death for patients with extensive full-thickness burns, chronic wounds, or genetic disorders such as bullous conditions. This engineering has been initiated based on the acute need in the 1980s and today, tissue-engineered skin is the reality. The human skin equivalents are available not only as models for permeation and toxicity screening, but are frequently applied in vivo as clinical skin substitutes. This review aims to introduce the most important recent development in the extensive field of tissue engineering and to describe already approved, commercially available skin substitutes in clinical use. =20
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  • Antithrombotic properties of sulfated wood-derived galactoglucomannans

    Doliska, Ales   Willfor, Stefan   Strnad, Simona   Ribitsch, Volker   Kleinschek, Karin Stana   Eklund, Patrik   Xu, Chunlin  

    Galactoglucomannans (GGMs) are water-soluble polysaccharides released and accumulated in process waters in the production of thermomechanical pulp. The general trend in the forestry industry is moving towards bio-refineries, for example utilizing these hemicelluloses as bioactive substances. At present, there is no industrial use of wood-derived mannans. In this study, GGMs extracted from thermomechanical pulp, as well as further carboxymethylated galactoglucomannans (CM-GGMs), were sulfated to increase their antithrombotic properties. The products were characterized with Fourier transform infrared spectroscopy, nuclear magnetic resonance and capillary electrophoresis. The carbohydrate composition and sulfur amounts were determined. The products' total charges were determined by polyelectrolyte titrations and their antithrombotic effect was measured based on the activated partial thromboplastin time. The results showed a significant increase in the antithrombotic effect of the sulfated galactoglucomannans from spruce wood and thus a potential new use for wood-derived mannans.
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  • Chitin nanowhisker - Inspired electrospun PVDF membrane for enhanced oil-water separation

    Gopi, Sreerag   Kargl, Rupert   Kleinschek, Karin Stana   Pius, Anitha   Thomas, Sabu  

    The requirement of promoting a revolution in filtration technology has led to growing devotion in advanced functional materials such as electrospun membranes for filtering devices as a solution for providing water at lower energy costs. In this study, electrospun polyvinylidene fluoride membranes were fabricated by reinforcing 0.5 and 1 wt. % of chitin nanowhiskers in order to improve their thermal stability, mechanical properties, pure water flux and oil-water filtration performance for the possible application as filtration membranes. Morphological analysis revealed the porous and fibrous structure of membranes which confirmed by BET surface area analysis. Incorporation of chitin nanowhiskers improved the mechanical properties of the membranes such as elongation at break and tensile strength (specifically at 1 wt. % of chitin nanowhisker) while resulted in substantial enhancement of their thermal properties. Furthermore, polyvinylidene fluoride/chitin nanowhisker membranes showed enhanced oil-water separation ability, while reinforcement of chitin nanowhisker led to increase pure water flux rate, which measured as a crucial point in filtration membranes. The oil-water separation results compared with a commercial polyvinylidene fluoride membrane and the results signified the potential of electrospun polyvinylidene fluoride/chitin nanowhisker to be used for filtration application.
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  • Reactive cellulose-based thin films - a concept for multifunctional polysaccharide surfaces

    Elschner, Thomas   Reishofer, David   Kargl, Rupert   Griesser, Thomas   Heinze, Thomas   Kleinschek, Karin Stana  

    Reactive coatings of hydroxyethyl cellulose furoate in the form of thin films, suitable for the covalent immobilization of functional molecules, were developed and characterized in this work. The cellulose furoate derivatives were synthesized under homogeneous conditions by esterification of hydroxyethyl cellulose with 2-furoic acid. Reactive platform layers of these furoates were obtained by chemical surface modification of spin coated thin films with N, N'-carbonyldiimidazole. This chemistry allowed the covalent immobilization of functional molecules bearing primary and secondary amines on the films. The degree of substitution of the furoate thin films and their amino functionalized counterparts was determined gravimetrically by a quartz crystal microbalance (QCM-D) and correlated with infrared and X-ray photoelectron spectroscopy and zeta-potential measurements. Scanning electron-and atomic force microscopy showed changes in the morphologies that were influenced by the chemical reactions on the surface. The concept presented can be seen as a versatile method for immobilizing amine-containing (bio-) molecules to polysaccharide surfaces with the furoates having the potential for further reversible cross-linking in Diels-Alder reactions.
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  • Analysis of galactoglucomannans from spruce wood by capillary electrophoresis

    Doliska, Ales   Strnad, Simona   Ribitsch, Volker   Kleinschek, Karin Stana   Willfor, Stefan   Saake, Bodo  

    The aim of this study was to setup a method for detection and quantification of monosaccharide components in technical galactoglucomannas (T-GGM) from spruce wood using capillary zone electrophoresis (CZE). CZE technique was optimised regarding borate buffer concentrations, EOF modifier application, and system pH. Aqueous solution of T-GGM was chemically hydrolysed by sulphuric acid, in an autoclave. In this way obtained monosaccharides were derivatized with 4-amino benzoic acid ethyl ester via reductive amination using sodium cyanoborohydride. The results of the optimisation procedure showed that the borate buffers at lowest concentrations (100 and 200 mM) with acetonitrile addition as EOF modifier gave the optimal measurement results, as it showed sufficient separation at relatively short migration times. The amounts of single monosaccharide components in the T-GGM samples obtained by the optimised CZE procedure were practically the same in comparison to the results of the well established HPLC-anion exchange chromatography. On the basis of this research, it was concluded that the capillary zone electrophoresis is an efficient analytical procedure for the characterisation of galactoglucomannans derived from softwoods.
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  • Functional dextran amino acid ester particles derived from N-protected S-trityl-L-cysteine

    Bratu拧a, Ana   Elschner, Thomas   Heinze, Thomas   Fr枚hlich, Eleonore   Hribernik, Silvo   Bo啪i膷, Mojca   沤agar, Ema   Kleinschek, Karin Stana   Thonhofer, Martin   Kargl, Rupert  

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  • Electrokinetic Properties of Polypropylene-Layered Silicate Nanocomposite Fibers

    Smole, Majda Sfiligoj   Stakne, Kristina   Kleinschek, Karin Stana   Kurecic, Mania   Bele, Marjan   Svetec, Diana Gregor   Ribitsch, Volker  

    Nanocomposite fibers based on polypropylene (PP) polymer were prepared with different content of nanofiller. Filaments were spun from an isotactic iPP homopolymer. Montmorillonite modified by N,N-dimethyl-N,N dioctadecylammonium cations was used for preparation of PP nanocomposite fibers. A PP grafted with acrylic acid was added as a coupling agent. Nanocomposite fibers were characterized, i.e., the surface morphology of PP nanocomposite fibers was observed and surface properties were defined by electrokinetic properties determination by zeta potential measurements. For particle distribution observation the plasma etching was involved as a method for sample preparation. The addition of nanoparticles has an impact on ZP value of nanofilled fibers, however, isoelectric point IEP is not significantly influenced by different concentrations of nanofiller. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1276-1281, 2009
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  • Carboxyl groups in pre-treated regenerated cellulose fibres

    Zemljic, Lidija Fras   Persin, Zdenka   Stenius, Per   Kleinschek, Karin Stana  

    The influence of peroxide bleaching and slack-mercerization on the amount of acidic groups in regenerated fibres (viscose, modal and lyocell) were studied. Conductometric titration was used to determine the total content of acidic carboxylic groups. Polyelectrolyte titration was used for surface and total charge determination, and to obtain information about the charge distribution and accessibilities of charged groups. Changes in fibre crystallinity to pre-treatment processes were characterized using iodine sorption (Schwertassek method) and correlated to treatments and the amount of carboxylic groups. For all three types of fibres the amount of accessible carboxyl groups was lowered by an increase in the degree of crystallinity. Bleaching with hydrogen peroxide causes some oxidative cellulose damage and, therefore, a larger amount of carboxyl groups (presumably formed at the end of cellulose chains). Slack-mercerization did not significantly change the total amount of acidic groups in the fibres, but their accessibility to cationic polyelectrolytes, in particular to polymers with high molecular weight was substantially lowered.
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  • Flame retardant activity of SiO2-coated regenerated cellulose fibres

    Hribernik, Silvo   Smole, Majda Sfiligoj   Kleinschek, Karin Stana   Bele, Marjan   Jamnik, Janez   Gaberscek, Miran  

    An alternative route to lower the flammability of viscose fibres is presented. Instead of adding a flame retardant to the viscose dope chemically, we have grown a layer of silica (SiO2) on the surface of a regenerated cellulose fibre via a sol-gel process. One set of samples was used as-received, while the other was pre-treated in an 18% NaOH solution, giving a rough, etched surface to the fibre. The different surface morphology of both fibre types triggered a different growth of silica layers. On an untreated fibre, silica formed a 300-400 nm thick surface layer containing a high density of cracks and holes. Conversely, on a NaOH pre-treated fibre, the silica layer intruded into fibre interior, adhered more tightly to the fibre structure and formed an almost defect-free, thin (100 nm) layer on the outer fibre surface. This type of silica layer increased the temperature at which the fibre started to decompose by 20 degrees C. It also hindered significantly the flow of oxygen to the generated volatiles during the thermal decomposition, and increased the temperature of glowing combustion of the residual char; the temperature of the corresponding exothermic peaks increased by ca. 20 degrees C and 40 degrees C. In contrast, the thermal effects of silica coatings that grew on an untreated fibre were much smaller. (c) 2007 Elsevier Ltd. All rights reserved.
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  • Characterization of nano-sized TiO2 suspensions for functional modification of polyester fabric

    Ojstrsek, Alenka   Kleinschek, Karin Stana   Fakin, Darinka  

    Three industrially-prepared (via the sulphate synthesis process) and commercially-available nanoTiO(2) colloidal suspensions were coated on polyester fabric using the conventional pad-dry-cure procedure, in order to enhance fabric functionalities by imparting self-cleaning and UV-protection ability. Various characterization techniques, i.e. transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and UV/Vis spectroscopy of the suspensions revealed the presence of anatase TiO2 spherical-shaped nanoparticles of different crystallite sizes, as well as its prominent absorption capacity within the UV region. Scanning electron microscopy (SEM) was adopted to analyse the morphological structure of nanoTiO(2)-modified PES fabrics. Furthermore, the photocatalytic activity was investigated through the discolourations of red wine and red beet stains under two types of light sources, i.e. direct day light and artificial UV light, by means of a spectrophotometiy. The UV-protective properties were also evaluated by calculating the ultraviolet protective factors of individual coated fabric. The obtained results show acceptable blocking properties against UV-rays, as well as the adequate self-cleaning abilities of TiO2-modified PES fabrics as governed by the types and concentrations of applied TiO2 suspension. (c) 2013 Elsevier B.V. All rights reserved.
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