Publications by authors named "Karin Stana-Kleinschek"

59 Publications

Influence of Charge and Heat on the Mechanical Properties of Scaffolds from Ionic Complexation of Chitosan and Carboxymethyl Cellulose.

ACS Biomater Sci Eng 2021 08 15;7(8):3618-3632. Epub 2021 Jul 15.

Institute of Chemistry and Technology of Biobased System (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.

As one of the most abundant, multifunctional biological polymers, polysaccharides are considered promising materials to prepare tissue engineering scaffolds. When properly designed, wetted porous scaffolds can have biomechanics similar to living tissue and provide suitable fluid transport, both of which are key features for in vitro and in vivo tissue growth. They can further mimic the components and function of glycosaminoglycans found in the extracellular matrix of tissues. In this study, we investigate scaffolds formed by charge complexation between anionic carboxymethyl cellulose and cationic protonated chitosan under well-controlled conditions. Freeze-drying and dehydrothermal heat treatment were then used to obtain porous materials with exceptional, unprecendent mechanical properties and dimensional long-term stability in cell growth media. We investigated how complexation conditions, charge ratio, and heat treatment significantly influence the resulting fluid uptake and biomechanics. Surprisingly, materials with high compressive strength, high elastic modulus, and significant shape recovery are obtained under certain conditions. We address this mostly to a balanced charge ratio and the formation of covalent amide bonds between the polymers without the use of additional cross-linkers. The scaffolds promoted clustered cell adhesion and showed no cytotoxic effects as assessed by cell viability assay and live/dead staining with human adipose tissue-derived mesenchymal stem cells. We suggest that similar scaffolds or biomaterials comprising other polysaccharides have a large potential for cartilage tissue engineering and that elucidating the reason for the observed peculiar biomechanics can stimulate further research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsbiomaterials.1c00534DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8396805PMC
August 2021

Water-based carbodiimide mediated synthesis of polysaccharide-amino acid conjugates: Deprotection, charge and structural analysis.

Carbohydr Polym 2021 Sep 20;267:118226. Epub 2021 May 20.

Institute of Chemistry and Technology of Biobased System (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria; Institute of Automation, Faculty of Electrical Engineering and Computer Science, University of Maribor, Koroška cesta 46, 2000 Maribor, Slovenia. Electronic address:

We report here a one-step aqueous method for the synthesis of isolated and purified polysaccharide-amino acid conjugates. Two different types of amino acid esters: glycine methyl ester and L-tryptophan methyl ester, as model compounds for peptides, were conjugated to the polysaccharide carboxymethylcellulose (CMC) in water using carbodiimide at ambient conditions. Detailed and systematic pH-dependent charge titration and spectroscopy (infrared, nuclear magnetic resonance: H, C- DEPT 135, H- C HMBC/HSQC correlation), UV-vis, elemental and ninhydrin analysis provided solid and direct evidence for the successful conjugation of the amino acid esters to the CMC backbone via an amide bond. As the concentration of amino acid esters increased, a conjugation efficiency of 20-80% was achieved. Activated charcoal aided base-catalyzed deprotection of the methyl esters improved the solubility of the conjugates in water. The approach proposed in this work should have the potential to tailor the backbone of polysaccharides containing di- or tri-peptides.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2021.118226DOI Listing
September 2021

Hybrid 3D Printing of Advanced Hydrogel-Based Wound Dressings with Tailorable Properties.

Pharmaceutics 2021 Apr 16;13(4). Epub 2021 Apr 16.

Department of Pharmacology, Faculty of Medicine, University of Maribor, Taborska Ulica 8, SI-2000 Maribor, Slovenia.

Despite the extensive utilization of polysaccharide hydrogels in regenerative medicine, current fabrication methods fail to produce mechanically stable scaffolds using only hydrogels. The recently developed hybrid extrusion-based bioprinting process promises to resolve these current issues by facilitating the simultaneous printing of stiff thermoplastic polymers and softer hydrogels at different temperatures. Using layer-by-layer deposition, mechanically advantageous scaffolds can be produced by integrating the softer hydrogel matrix into a stiffer synthetic framework. This work demonstrates the fabrication of hybrid hydrogel-thermoplastic polymer scaffolds with tunable structural and chemical properties for applications in tissue engineering and regenerative medicine. Through an alternating deposition of polycaprolactone and alginate/carboxymethylcellulose gel strands, scaffolds with the desired architecture (e.g., filament thickness, pore size, macro-/microporosity), and rheological characteristics (e.g., swelling capacity, degradation rate, and wettability) were prepared. The hybrid fabrication approach allows the fine-tuning of wettability (approx. 50-75°), swelling (approx. 0-20× increased mass), degradability (approx. 2-30+ days), and mechanical strength (approx. 0.2-11 MPa) in the range between pure hydrogels and pure thermoplastic polymers, while providing a gradient of surface properties and good biocompatibility. The controlled degradability and permeability of the hydrogel component may also enable controlled drug delivery. Our work shows that the novel hybrid hydrogel-thermoplastic scaffolds with adjustable characteristics have immense potential for tissue engineering and can serve as templates for developing novel wound dressings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/pharmaceutics13040564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8073841PMC
April 2021

Anticoagulant Activity of Cellulose Nanocrystals from Isora Plant Fibers Assembled on Cellulose and SiO Substrates via a Layer-by-Layer Approach.

Polymers (Basel) 2021 Mar 18;13(6). Epub 2021 Mar 18.

Institute for Chemistry and Technology of Biobased Systems (IBioSys), Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.

In this study, we report the isolation of cellulose nanocrystals (CNCs) from Isora plant fibers by sulfuric acid hydrolysis and their assembly on hydrophilic cellulose and silicon-di-oxide (SiO) surfaces via a layer-by-layer (LBL) deposition method. The isolated CNCs were monodispersed and exhibited a length of 200-300 nm and a diameter of 10-20 nm, a negative zetapotential (-34-39 mV) over a wide pH range, and high stability in water at various concentrations. The multi-layered structure, adsorbed mass, conformational changes, and anticoagulant activity of sequentially deposited anionic (sulfated) CNCs and cationic polyethyleneimine (PEI) on the surfaces of cellulose and SiO by LBL deposition were investigated using a quartz crystal microbalance technique. The organization and surface features (i.e., morphology, thickness, wettability) of CNCs adsorbed on the surfaces of PEI deposited at different ionic strengths (50-300 mM) of sodium chloride were analysed in detail by profilometry layer-thickness, atomic force microscopy and contact angle measurements. Compared to cellulose (control sample), the total coagulation time and plasma deposition were increased and decreased, respectively, for multilayers of PEI/CNCs. This study should provide new possibilities to fabricate and tailor the physicochemical properties of multilayer films from polysaccharide-based nanocrystals for various biomedical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym13060939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003298PMC
March 2021

Protein repellent anti-coagulative mixed-charged cellulose derivative coatings.

Carbohydr Polym 2021 Feb 25;254:117437. Epub 2020 Nov 25.

Institute for Chemistry and Technology of Biobased Systems, Graz University of Technology, Stremayrgasse 9, A-8010, Graz, Austria.

This study describes the formation of cellulose based polyelectrolyte charge complexes on the surface of biodegradable polycaprolactone (PCL) thin films. Anionic sulphated cellulose (CS) and protonated cationic amino cellulose (AC) were used to form these complexes with a layer-by-layer coating technique. Both polyelectrolytes were analyzed by charge titration methods to elucidate their pH-value dependent protonation behavior. A quartz crystal microbalance with dissipation (QCM-D) in combination with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to follow the growth, stability and water content of up to three AC/CS bi-layers in aqueous environment. This was combined with coagulation studies on one, two and three bilayers of AC/CS, measuring the thrombin formation rate and the total coagulation time of citrated blood plasma with QCM-D. Stable mixed charged bilayers could be prepared on PCL and significantly higher masses of AC than of CS were present in these complexes. Strong hydration due to the presence of ammonium and sulphate substituents on the backbone of cellulose led to a significant BSA repellent character of three bilayers of AC/CS coatings. The total plasma coagulation time was increased in comparison to neat PCL, indicating an anticoagulative nature of the coatings. Surprisingly, a coating solely composed of an AC layer significantly prolonged the total coagulation time on the surfaces although it did not prevent fibrinogen deposition. It is suggested that these cellulose derivative-based coatings can therefore be used to prevent unwanted BSA deposition and fibrin clot formation on PCL to foster its biomedical application.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2020.117437DOI Listing
February 2021

Defluorination of Polytetrafluoroethylene Surface by Hydrogen Plasma.

Polymers (Basel) 2020 Nov 29;12(12). Epub 2020 Nov 29.

Institute of Chemistry and Technology of Biobased Systems, Graz University of Technology, Rechbauerstraße 12, 8010 Graz, Austria.

Defluorination of polytetrafluoroethylene (PTFE) surface film is a suitable technique for tailoring its surface properties. The influence of discharge parameters on the surface chemistry was investigated systematically using radio-frequency inductively coupled H plasma sustained in the E- and H-modes at various powers, pressures and treatment times. The surface finish was probed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The measurements of water contact angles (WCA) showed increased wettability of the pristine PTFE; however, they did not reveal remarkable modification in the surface chemistry of the samples treated at various discharge parameters. By contrast, the combination of XPS and ToF-SIMS, however, revealed important differences in the surface chemistry between the E- and H-modes. A well-expressed minimum in the fluorine to carbon ratio F/C as low as 0.2 was observed at the treatment time as short as 1 s when plasma was in the H-mode. More gradual surface chemistry was observed when plasma was in the E-mode, and the minimal achievable F/C ratio was about 0.6. The results were explained by the synergistic effects of hydrogen atoms and vacuum ultraviolet radiation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym12122855DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7760809PMC
November 2020

Comparison of Trimethylsilyl Cellulose-Stabilized Carbonate and Hydroxide Nanoparticles for Deacidification and Strengthening of Cellulose-Based Cultural Heritage.

ACS Omega 2020 Nov 6;5(45):29243-29256. Epub 2020 Nov 6.

Laboratory for Characterization and Processing of Polymers, Faculty of Mechanical Engineering, University of Maribor, Smetanova Ulica 17, 2000 Maribor, Slovenia.

Herein, colloidal dispersions of alkaline nanoparticles (NPs: CaCO and Mg(OH)) are stabilized by trimethylsilyl cellulose (TMSC) in hexamethyldisiloxane and employed to treat historical wood pulp paper by an effortless dip-coating technique. Both alkaline NPs exhibit high stability and no size and shape changes upon stabilization with the polymer, as shown by UV-vis spectroscopy and transmission electron microscopy. The long-term effect of NP/TMSC coatings is investigated in detail using accelerated aging. The results from the pH-test and back-titration of coated papers show a complete acid neutralization (pH ∼ 7.4) and introduction of adequate alkaline reserve even after prolonged accelerated aging. Scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and infrared and water contact angle measurements showed the introduction of a thin and smooth hydrophobic NP/TMSC coating on the paper fibers. Acid-catalyzed desilylation of TMSC was observed by declining C-Si infrared absorbance peaks upon aging. The CaCO coatings are superior to Mg(OH) with respect to a reduced yellowing and lower cellulose degradation upon aging as shown by colorimetric measurements and degree of polymerization analysis. The tensile strength and folding endurance of coated and aged papers are improved to 200-300 and 50-70% as illustrated by tensile strength and double folding endurance measurements.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsomega.0c03997DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7676302PMC
November 2020

How can we understand the influence of nanoparticles on the coagulation of blood?

Nanomedicine (Lond) 2020 08 17;15(20):1923-1926. Epub 2020 Jul 17.

Institute for Chemistry & Technology of Biobased Systems (IBIOSYS), Graz University of Technology, Stremayrgasse 9, Graz, 8010, Austria.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2217/nnm-2020-0177DOI Listing
August 2020

Polysaccharide-Based Bioink Formulation for 3D Bioprinting of an In Vitro Model of the Human Dermis.

Nanomaterials (Basel) 2020 Apr 11;10(4). Epub 2020 Apr 11.

Institute of Biomedical Sciences, Faculty of Medicine, University of Maribor, Taborska ulica 8, 2000 Maribor, Slovenia.

Limitations in wound management have prompted scientists to introduce bioprinting techniques for creating constructs that can address clinical problems. The bioprinting approach is renowned for its ability to spatially control the three-dimensional (3D) placement of cells, molecules, and biomaterials. These features provide new possibilities to enhance homology to native skin and improve functional outcomes. However, for the clinical value, the development of hydrogel bioink with refined printability and bioactive properties is needed. In this study, we combined the outstanding viscoelastic behavior of nanofibrillated cellulose (NFC) with the fast cross-linking ability of alginate (ALG), carboxymethyl cellulose (CMC), and encapsulated human-derived skin fibroblasts (hSF) to create a bioink for the 3D bioprinting of a dermis layer. The shear thinning behavior of hSF-laden bioink enables construction of 3D scaffolds with high cell density and homogeneous cell distribution. The obtained results demonstrated that hSF-laden bioink supports cellular activity of hSF (up to 29 days) while offering proper printability in a biologically relevant 3D environment, making it a promising tool for skin tissue engineering and drug testing applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nano10040733DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7221685PMC
April 2020

Chemical Structure-Antioxidant Activity Relationship of Water-Based Enzymatic Polymerized Rutin and Its Wound Healing Potential.

Polymers (Basel) 2019 Sep 26;11(10). Epub 2019 Sep 26.

Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.

The flavonoid rutin (RU) is a known antioxidant substance of plant origin. Its potential application in pharmaceutical and cosmetic fields is, however, limited, due to its low water solubility. This limitation can be overcome by polymerization of the phenolic RU into polyrutin (PR). In this work, an enzymatic polymerization of RU was performed in water, without the addition of organic solvents. Further, the chemical structure of PR was investigated using H NMR, and FTIR spectroscopy. Size-exclusion chromatography (SEC) was used to determine the molecular weight of PR, while its acid/base character was studied by potentiometric charge titrations. Additionally, this work investigated the antioxidant and free radical scavenging potential of PR with respect to its chemical structure, based on its ability to (i) scavenge non biological stable free radicals (ABTS), (ii) scavenge biologically important oxidants, such as O•, NO•, and OH•, and (iii) chelate Fe. The influence of PR on fibroblast and HaCaT cell viability was evaluated to confirm the applicability of water soluble PR for wound healing application.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym11101566DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835416PMC
September 2019

Affinity of Serum Albumin and Fibrinogen to Cellulose, Its Hydrophobic Derivatives and Blends.

Front Chem 2019 6;7:581. Epub 2019 Sep 6.

Laboratory for Characterization and Processing of Polymers, Faculty of Mechanical Engineering, University of Maribor, Maribor, Slovenia.

This work describes the preparation of spin-coated thin polymer films composed of cellulose (CE), ethyl cellulose (EC), and cellulose acetate (CA) in the form of bi- or mono-component coatings on sensors of a quartz crystal microbalance with dissipation monitoring (QCM-D). Depending on the composition and derivative, hydrophilicity can be varied resulting in materials with different surface properties. The surfaces of mono- and bi-component films were also analyzed by atomic force microscopy (AFM) and large differences in the morphologies were found comprising nano- to micrometer sized pores. Extended protein adsorption studies were performed by a QCM-D with 0.1 and 10 mg mL bovine serum albumin (BSA) and 0.1 and 1 mg mL fibrinogen from bovine plasma in phosphate buffered saline. Analysis of the mass of bound proteins was conducted by applying the Voigt model and a comparison was made with the Sauerbrey wet mass of the proteins for all films. The amount of deposited proteins could be influenced by the composition of the films. It is proposed that the observed effects can be exploited in biomaterial science and that they can be used to extent the applicability of bio-based polymer thin films composed of commercial cellulose derivatives.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fchem.2019.00581DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6743410PMC
September 2019

Functional dextran amino acid ester particles derived from N-protected S-trityl-L-cysteine.

Colloids Surf B Biointerfaces 2019 Sep 4;181:561-566. Epub 2019 Jun 4.

Laboratory for Characterization and Processing of Polymers (LCPP), Faculty of Mechanical Engineering, University of Maribor, Smetanova ulica 17, SI-2000, Maribor, Slovenia; Institute of Paper, Pulp and Fibre Technology (IPZ), Graz University of Technology, Inffeldgasse 23, A - 8010, Graz, Austria. Electronic address:

This work describes the derivatization of dextran using N-(tert-butyloxycarbonyl)-S-(trityl)-L-cysteine in the presence of N,N'-carbonyldiimidazole (CDI) as a coupling agent. Homogeneous reactions in dimethyl sulfoxide allowed for an efficient coupling of the amino acid derivative to the polymer backbone. Derivatization was confirmed by infrared and C NMR spectroscopy, size exclusion chromatography and elemental analysis. The presence of hydrophobic protecting groups resulted in a product that can be shaped into water-insoluble particles stable in an aqueous environment and non-toxic for lung epithelial cells. It is suggested that materials composed of ester bonds between amino acids and polysaccharides are useful for targeted drug delivery, bio-imaging or surface functionalization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.colsurfb.2019.06.005DOI Listing
September 2019

Nano- and Micropatterned Polycaprolactone Cellulose Composite Surfaces with Tunable Protein Adsorption, Fibrin Clot Formation, and Endothelial Cellular Response.

Biomacromolecules 2019 06 29;20(6):2327-2337. Epub 2019 May 29.

Laboratory for Characterisation and Processing of Polymers, Faculty of Mechanical Engineering , University of Maribor , Smetanova ulica17 , 2000 Maribor , Slovenia.

This work describes the interaction of the human blood plasma proteins albumin, fibrinogen, and γ-globulins with micro- and nanopatterned polymer interfaces. Protein adsorption studies were correlated with the fibrin clotting time of human blood plasma and with the growth of primary human pulmonary artery endothelial cells (hECs) on these patterns. It was observed that blends of polycaprolactone (PCL) and trimethylsilyl-protected cellulose form various thin-film patterns during spin coating, depending on the mass ratio of the polymers in the spinning solutions. Vapor-phase acid-catalyzed deprotection preserves these patterns but yields interfaces that are composed of hydrophilic cellulose domains enclosed by hydrophobic PCL. The blood plasma proteins are repelled by the cellulose domains, allowing for a suggested selective protein deposition on the PCL domains. An inverse proportional correlation is observed between the amount of cellulose present in the films and the mass of irreversibly adsorbed proteins. This results in significantly increased fibrin clotting times and lower masses of deposited clots on cellulose-containing films as revealed by quartz crystal microbalance with dissipation measurements. Cell viability of hECs grown on these surfaces was directly correlated with higher protein adsorption and faster clot formation. The results show that presented patterned polymer composite surfaces allow for a controllable blood plasma protein coagulation and a significant biological response from hECs. It is proposed that this knowledge can be utilized in regenerative medicine, cell cultures, and artificial vascular grafts by a careful choice of polymers and patterns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.biomac.9b00304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750646PMC
June 2019

Polysaccharide Thin Solid Films for Analgesic Drug Delivery and Growth of Human Skin Cells.

Front Chem 2019 9;7:217. Epub 2019 Apr 9.

Department of Pharmacology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.

Chronic wounds not only lower the quality of patient's life significantly, but also present a huge financial burden for the healthcare systems around the world. Treatment of larger wounds often requires the use of more complex materials, which can ensure a successful renewal or replacement of damaged or destroyed tissues. Despite a range of advanced wound dressings that can facilitate wound healing, there are still no clinically used dressings for effective local pain management. Herein, alginate (ALG) and carboxymethyl cellulose (CMC), two of the most commonly used materials in the field of chronic wound care, and combination of ALG-CMC were used to create a model wound dressing system in the form of multi-layered thin solid films using the spin-assisted layer-by-layer (LBL) coating technique. The latter multi-layer system was used to incorporate and study the release kinetics of analgesic drugs such as diclofenac and lidocaine at physiological conditions. The wettability, morphology, physicochemical and surface properties of the coated films were evaluated using different surface sensitive analytical tools. The influence of incorporated drug molecules on the surface properties (e.g., roughness) and on the proliferation of human skin cells (keratinocytes and skin fibroblasts) was further evaluated. The results obtained from this preliminary study should be considered as the basis for the development "real" wound dressing materials and for 3D bio-printing applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fchem.2019.00217DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6466929PMC
April 2019

Systematic Evaluation of a Diclofenac-Loaded Carboxymethyl Cellulose-Based Wound Dressing and Its Release Performance with Changing pH and Temperature.

AAPS PharmSciTech 2019 Jan 2;20(1):29. Epub 2019 Jan 2.

Faculty of Medicine, Department of Pharmacology, University of Maribor, 2000, Maribor, Slovenia.

Development of drug-loaded wound dressings is often performed without systematic consideration of the changing wound environment that can influence such materials' performance. Among the crucial changes are the wound pH and temperature, which have an immense effect on the drug release. Detailed release studies based on the consideration of these changing properties provide an important aspect of the in vitro performance testing of novel wound dressing materials. A sodium carboxymethyl cellulose-based wound dressing, with the incorporated non-steroidal anti-inflammatory drug diclofenac, was developed and characterised in regard to its physico-chemical, structural and morphological properties. Further, the influence of pH and temperature were studied on the drug release. Finally, the biocompatibility of the wound dressing towards human skin cells was tested. Incorporation of diclofenac did not alter important properties (water retention value, air permeability) of the host material. Changes in the pH and temperature were shown to influence the release performance and have to be accounted for in the evaluation of such dressings. Furthermore, the knowledge about the potential changes of these parameters in the wound bed could be used potentially to predict, and potentially even to control the drug release from the developed wound dressing. The prepared wound dressing was also proven biocompatible towards human skin cells, making it interesting for potential future use in the clinics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1208/s12249-018-1236-4DOI Listing
January 2019

Chitin nanowhisker - Inspired electrospun PVDF membrane for enhanced oil-water separation.

J Environ Manage 2018 Dec 15;228:249-259. Epub 2018 Sep 15.

International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, 686560, Kerala, India. Electronic address:

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jenvman.2018.09.039DOI Listing
December 2018

Nanofibrous polysaccharide hydroxyapatite composites with biocompatibility against human osteoblasts.

Carbohydr Polym 2017 Dec 30;177:388-396. Epub 2017 Aug 30.

University of Maribor, Faculty of Mechanical Engineering, Laboratory for Characterisation and Processing of Polymers, Smetanova 17, SI-2000 Maribor, Slovenia.

Regenerative medicine has a high demand for defined scaffold materials that promote cell growth, stabilize the tissue during maturation and provide a proper three dimensional structure that allows the exchange of nutrients. In many instances nanofiber composites have already shown their potential for such applications. This work elaborates the development of polysaccharide based nanofibers with integrated hydroxyapatite nanoparticles. A detailed study on the formation of electrospun nanofibres from aqueous mixtures of carboxymethyl cellulose polyethylene oxide was performed. The influence of different processing conditions and spinning solution properties using a nozzle-less electrospinning device was systematically studied. Optimized parameters were used to incorporate hydroxyapatite nanoparticles into the fibers. Nanofibers were additionally hydrophobized with alkenyl succinic anhydride (ASA) to render them insoluble in water. The nanofiber webs were thoroughly investigated with respect to morphology, chemical composition and inorganic content. Time dependent biocompatibility testing of the materials with human bone-derived osteoblasts showed no significant reduction in cell viability for the developed materials composed of carboxymethyl cellulose/polyethyleneoxide. Cells grown on hydrophobized materials show similar viability as those grown on a commercial collagen/apatite matrix.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2017.08.111DOI Listing
December 2017

Multilayered Polysaccharide Nanofilms for Controlled Delivery of Pentoxifylline and Possible Treatment of Chronic Venous Ulceration.

Biomacromolecules 2017 Sep 22;18(9):2732-2746. Epub 2017 Aug 22.

University of Maribor , Faculty of Medicine, Institute of Biomedical Sciences, Taborska ulica 8, SI-2000 Maribor, Slovenia.

Local drug delivery systems made from nontoxic polysaccharide nanofilms have an enormous potential in wound care. A detailed understanding of the structural, surface, physicochemical, and cytotoxic properties of such systems is crucial to design clinically efficacious materials. Herein, we fabricated polysaccharide-based nanofilms onto either a 2D model (SiO and Au sensors) or on nonwoven alginate 3D substrates using an alternating assembly of N,N,N-trimethylchitosan (TMC) and alginic acid (ALG) by a spin-assisted layer-by-layer (LbL) technique. These TMC/ALG multilayered nanofilms are used for a uniform encapsulation and controlled release of pentoxifylline (PTX), a potent anti-inflammatory drug for treatment of the chronic venous ulceration. We show a tailorable film growth and mass, morphology, as well as surface properties (charge, hydrophilicity, porosity) of the assembled nanofilms through control of the coating during the spin-assisted assembly. The uniform distribution of the encapsulated PTX in the TMC/ALG nanofilms is preserved even with when the amount of the incorporated PTX increases. The PTX release mechanism from the model and real systems is studied in detail and is very comparable for both systems. Finally, different cell-based assays illustrated the potential of the TMC/ALG multilayer system in wound care (e.g., treatment chronic venous ulceration) applications, including a decrease of TNF-α secretion, a common indicator of inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.biomac.7b00523DOI Listing
September 2017

Environmentally friendly procedure for in-situ coating of regenerated cellulose fibres with silver nanoparticles.

Carbohydr Polym 2017 May 20;163:92-100. Epub 2017 Jan 20.

Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, SI-2000 Maribor, Slovenia. Electronic address:

This study introduces a novel green in-situ procedure for introduction of silver nanoparticles (Ag NPs) on and into cellulose fibres in a three-stage process. First-stage of the process includes the activation of cellulose fibres in alkaline solution, followed by reduction of silver nitrate to Ag NPs in the second stage, while the last stage of process involves washing and neutralization of fibres. Efficiency of the method towards incorporation of silver particles into the fibres' internal structure was characterized; the coatings' morphology and determination of spatial presence of Ag particles were imagining by the scanning electron microscopy and accompanying energy dispersive x-ray spectroscopy analysis; prepared fibres have superior durability of particles' coating against washing and excellent antimicrobial activity even after 20 washing cycles. Additionally, the water retention of silver treated fibres was improved, while the mechanical properties were not significantly impaired.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2017.01.060DOI Listing
May 2017

Synthesis and film formation of furfuryl- and maleimido carbonic acid derivatives of dextran.

Carbohydr Polym 2017 Apr 26;161:1-9. Epub 2016 Dec 26.

Center of Excellence for Polysaccharide Research, Institute for Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, Humboldtstraße 10, D-07743 Jena, Germany. Electronic address:

Carbonic acid derivatives of dextran possessing furfuryl- and maleimido moieties were synthesized and processed into thin films by spin coating. First, products with different degrees of substitution (DS) of up to 3.0 and substitution patterns were obtained and characterized by NMR- and FTIR spectroscopy, as well as elemental analysis. Thin films possessing maleimide groups were obtained by spin coating of maleimido dextran (furan-protected) and dextran furfuryl carbamate that was converted with bismaleimide. The removal of the protecting group (furan) on the thin film was monitored by QCM-D and compared with gravimetric analysis of the bulk material. Film morphology and wettability were determined by means of AFM and contact angle measurements.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2016.12.038DOI Listing
April 2017

Interaction of Tissue Engineering Substrates with Serum Proteins and Its Influence on Human Primary Endothelial Cells.

Biomacromolecules 2017 02 24;18(2):413-421. Epub 2017 Jan 24.

Institute for Chemistry and Technology of Materials, Graz University of Technology , Stremayrgasse 9, 8010 Graz, Austria.

Polymer-based biomaterials particularly polycaprolactone (PCL) are one of the most promising substrates for tissue engineering. The surface chemistry of these materials plays a major role since it governs protein adsorption, cell adhesion, viability, degradation, and biocompatibility in the first place. This study correlates the interaction of the most abundant serum proteins (albumin, immunoglobulins, fibrinogen) with the surface properties of PCL and its influence on the morphology and metabolic activity of primary human arterial endothelial cells that are seeded on the materials. Prior to that, thin films of PCL are manufactured by spin-coating and characterized in detail. A quartz crystal microbalance with dissipation (QCM-D), a multiparameter surface plasmon resonance spectroscopy instrument (MP-SPR), wettability data, and atomic force microscopy are combined to elucidate the pH-dependent protein adsorption on the PCL substrates. Primary endothelial cells are cultured on the protein modified polymer, and conclusions are drawn on the significant impact of type and form of proteins coatings on cell morphology and metabolic activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.biomac.6b01504DOI Listing
February 2017

Tuning of cellulose fibres' structure and surface topography: Influence of swelling and various drying procedures.

Carbohydr Polym 2016 Sep 13;148:227-35. Epub 2016 Apr 13.

Faculty of Mechanical Engineering, University of Maribor, 2000 Maribor, Slovenia. Electronic address:

Presented study deals with the pre-treatment of cellulose fibres with the aim to activate their surface and to enlarge their pore system, leading to an enhancement of fibres' affinity for subsequent functionalization processes. Swelling of fibres in aqueous solutions of sodium hydroxide opens their fibrillar structure, while freezing and freeze-drying retain this enlargement of the pore system, in contrast with conventional air or elevated temperature drying. Effect of different pre-treatment procedures on fibres' supramolecular structure, enlargement of their pore system, surface topography, zeta potential and mechanical properties was investigated. Degree of enhancement of the pore system depends on the concentration of sodium hydroxide and type of freezing; higher alkali concentrations are more effective, but at the cost of extensive deterioration of mechanical properties. Swelling of fibres in lower concentrations of NaOH, in combination with freeze drying, offers an acceptable compromise between enhancement of the fibres' pore system, changes in surface potential and tensile properties of treated fibres. Design of a suitable regime of swelling and drying of cellulose fibres results in an effective procedure for controlled tuning of their surface topography in combination with an increase of the available internal surface area and pore volume.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2016.04.053DOI Listing
September 2016

Exploring Nonspecific Protein Adsorption on Lignocellulosic Amphiphilic Bicomponent Films.

Biomacromolecules 2016 Mar 18;17(3):1083-92. Epub 2016 Feb 18.

Institute for Chemistry and Technology of Materials, Graz University of Technology , Stremayrgasse 9, 8010 Graz, Austria.

In this contribution, we explore the interaction of lignocellulosics and proteins aiming at a better understanding of their synergistic role in natural systems. In particular, the manufacturing and characterization of amphiphilic bicomponent thin films composed of hydrophilic cellulose and a hydrophobic lignin ester in different ratios is presented which may act as a very simplified model for real systems. Besides detailed characterizations of the films and mechanisms to explain their formation, nonspecific protein adsorption using bovine serum albumin (BSA) onto the films was studied using a quartz crystal microbalance with dissipation (QCM-D). As it turns out, the rather low nonspecific protein adsorption of BSA on cellulose is further reduced when these hydrophobic lignins are incorporated into the films. The lignin ester acts in these blend films as sacrificial component, probably via an emulsification mechanism. Additionally, the amphiphilicity of the films may prevent the adsorption of BSA as well. Although there are some indications, it remains unclear whether any kind of protein interactions in such systems are of specific nature.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.biomac.5b01700DOI Listing
March 2016

Advanced therapies of skin injuries.

Wien Klin Wochenschr 2015 Dec 24;127 Suppl 5:S187-98. Epub 2015 Sep 24.

University Medical Centre Ljubljana, Ljubljana, Slovenia.

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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00508-015-0859-7DOI Listing
December 2015

Designing Hydrophobically Modified Polysaccharide Derivatives for Highly Efficient Enzyme Immobilization.

Biomacromolecules 2015 Aug 31;16(8):2403-11. Epub 2015 Jul 31.

βInstitute for Engineering Materials and Design, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia.

In this contribution, a hydrophobically modified polysaccharide derivative is synthesized in an eco-friendly solvent water by conjugation of benzylamine with the backbone of the biopolymer. Owing to the presence of aromatic moieties, the resulting water-soluble polysaccharide derivative self-assembles spontaneously and selectively from solution on the surface of nanometric thin films and sheets of polystyrene (PS). The synthetic polymer modified in this way bears a biocompatible nanolayer suitable for the immobilization of horseradish peroxidase (HRP), a heme-containing metalloenzyme often employed in biocatalysis and biosensors. Besides the detailed characterization of the polysaccharide derivative, a quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM) are used to investigate the binding efficiency and interaction of HRP with the tailored polysaccharide interfaces. Subsequent enzyme activity tests reveal details of the interaction of HRP with the solid support. The novel polysaccharide derivative and its use as a material for the selective modification of PS lead to a beneficial, hydrophilic environment for HRP, resulting in high enzymatic activities and a stable immobilization of the enzyme for biocatalytic and analytic purposes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.biomac.5b00638DOI Listing
August 2015

Covalent Binding of Heparin to Functionalized PET Materials for Improved Haemocompatibility.

Materials (Basel) 2015 Mar 31;8(4):1526-1544. Epub 2015 Mar 31.

Plasma Laboratory, Institute Jozef Stefan, Jamova 39, Ljubljana 1000, Slovenia.

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 NH 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ma8041526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507051PMC
March 2015

A review of herbal medicines in wound healing.

Int J Dermatol 2015 Jul 24;54(7):740-51. Epub 2015 Mar 24.

Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia.

Herbs have been integral to both traditional and non-traditional forms of medicine dating back at least 5000 years. The enduring popularity of herbal medicines may be explained by the perception that herbs cause minimal unwanted side effects. More recently, scientists increasingly rely on modern scientific methods and evidence-based medicine to prove efficacy of herbal medicines and focus on better understanding of mechanisms of their action. However, information concerning quantitative human health benefits of herbal medicines is still rare or dispersed, limiting their proper valuation. Preparations from traditional medicinal plants are often used for wound healing purposes covering a broad area of different skin-related diseases. Herbal medicines in wound management involve disinfection, debridement, and provision of a suitable environment for aiding the natural course of healing. Here we report on 22 plants used as wound healing agents in traditional medicine around the world. The aim of this review is therefore to review herbal medicines, which pose great potential for effective treatment of minor wounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/ijd.12766DOI Listing
July 2015

Gold nanoparticles in the engineering of antibacterial and anticoagulant surfaces.

Carbohydr Polym 2015 Mar 22;117:34-42. Epub 2014 Sep 22.

Institute for Chemistry, University of Graz, Graz, Austria.

Simultaneous antibacterial and anticoagulant surfaces have been prepared by immobilization of engineered gold nanoparticles onto different kinds of surfaces. The gold nanoparticle core is surrounded by a hemocompatible, anticoagulant polysaccharide, 6-O chitosan sulfate, which serves as reduction and stabilizing agent for the generation of gold nanoparticles in a microwave mediated reaction. The particle suspension shows anticoagulant activity, which is investigated by aPTT and PT testing on citrated blood samples of three patients suffering from congenital or acquired bleeding disorders. The amount of nanoparticles deposited on the surfaces is quantified by a quartz crystal microbalance with dissipation unit. All gold containing surfaces exhibit excellent antimicrobial properties against the chosen model organism, Escherichia coli MG 1655 [R1-16]. Moreover, blood plasma coagulation times of the surfaces are increased after deposition of the engineered nanoparticles as demonstrated by QCM-D.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2014.08.116DOI Listing
March 2015

Antifouling coating of cellulose acetate thin films with polysaccharide multilayers.

Carbohydr Polym 2015 Feb 26;116:149-58. Epub 2014 Apr 26.

Institute of Chemistry, Karl-Franzens-University Graz, Heinrichstraße 28, 8010 Graz, Austria.

In this investigation, partially deacetylated cellulose acetate (DCA) thin films were prepared and modified with hydrophilic polysaccharides with the layer-by-layer (LbL) technique. As polysaccharides, chitosan (CHI) and carboxymethyl cellulose (CMC) were used. DCA thin films were manufactured by exposing spin coated cellulose acetate to potassium hydroxide solutions for various times. The deacetylation process was monitored by attenuated total reflectance-infrared spectroscopy, film thickness and static water contact angle measurements. A maximum of three bilayers was created from the alternating deposition of CHI and CMC on the DCA films under two different conditions namely constant ionic strengths and varying pH values of the CMC solutions. Precoatings of CMC at pH 2 were used as a base layer. The sequential deposition of CMC and CHI was investigated with a quartz crystal microbalance with dissipation, film thickness, static water contact angle and atomic force microscopy (AFM) measurements. The versatility and applicability of the developed functional coatings was shown by removing the multilayers by rinsing with mixtures containing HCl/NaCl. The developed LbL coatings are used for studying the fouling behavior of bovine serum albumin (BSA).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2014.04.068DOI Listing
February 2015

Film formation of ω-aminoalkylcellulose carbamates--a quartz crystal microbalance (QCM) study.

Carbohydr Polym 2015 Feb 12;116:111-6. Epub 2014 May 12.

Center of Excellence for Polysaccharide Research, Institute for Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, Humboldtstraße 10, D-07743 Jena, Germany. Electronic address:

The film formation of novel ω-aminoalkylcellulose carbamates on gold surface was studied by means of quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). The influence of the pH value of the buffer solution, the concentration, the degree of polymerization, and the structure (spacer length) of the polymers on the coating was investigated. The layer formation was explained based on the pKa value and the degree of substitution of the ω-aminoalkylcellulose carbamates determined by potentiometric titration. This work provides novel supporting materials that might be applied in field of immobilization of biomolecules.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.carbpol.2014.04.101DOI Listing
February 2015
-->