Kateřina Kolářová

Antibacterial wound dressing: plasma treatment effect on chitosan impregnation and in situ synthesis of silver chloride on cellulose surface

The treatment of wounds often deals with bacterial infections which complicate healing. Our aim was to prepare cellulose wound dressings with antibacterial properties. A cellulose dressing was exposed to argon plasma discharge, impregnated with chitosan and then silver chloride particles were precipitated in situ on the dressings surface. The effect of plasma treatment on both the chitosan impregnation and silver chloride precipitation was studied, together with the antibacterial properties of the prepared dressings. The materials were characterized by optical microscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), goniometry, absorption atomic spectroscopy (AAS) and zeta potential measurement. The antibacterial potency of the dressings was assessed using environmental bacterial strains of Escherichia coli and Staphylococcus epidermidis. Plasma treatment had a positive effect on both chitosan impregnation and the silver chloride precipitation. The antibacterial tests performed on these wound dressings exhibited growth prevention of the two representative strains of Gram-positive and Gram-negative bacteria. These results are of medical interest.

Transfer of metallic nanostructures from solid-state substrates

A novel technique for transferring dimensionally diverse metallic nanostructures from different kinds of substrates into chitosan foil is described. We were able to obtain nanoparticles of different sizes and shapes incorporated into the surface of a biocompatible polymer with no restrictions on the process used to manufacture the structures supported on the initial substrate. We successfully transferred silver nanowires (NWs) from a nano-patterned polyethyleneterephthalate (PET) foil, and silver nanoparticles (NPs) from a microscope cover glass.

Cell Adhesion and Proliferation on Modified Polyethylene

The interaction of cells with polymers is important for their potential applications in medicine and various areas of biotechnology. Their physico-chemical surface properties strongly influence the cell morphology, adhesion and growth. Physical and chemical properties of pristine and modified polyethylene (PE) films were studied. PE was modified by Ar plasma (0–400 s, 2.0 W) and than grafted with amino acid (glycine). Structural and morphological changes of polymer were studied by goniometry and Rutherford back-scattering (RBS). The interaction of these samples with vascular smooth muscle cell (VSMC) from the rat aorta was studied. Number and morphology of the adhered and proliferated cell on the pristine and modified PE was studied in vitro method. It was found that wetting angle of the modified films decreased with exposure time. Experiments in vitro indicated that the adhesion and proliferation of VSMC is increasing function of degradation time and glycine grafting.

Effect of VUV-excimer lamp treatment on cellulose fiber

ABSTRACT Vacuum ultra-violet-excimer lamp effect on cellulose fiber was studied to examine the effect on surface chemistry of cellulose. We focused on composition of a superficial layer of cellulose, which was studied by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Along with the surface composition, surface morphology was studied by scanning electron microscopy. The vacuum ultra-violet-excimer exposure in various atmospheres can be advantageously utilized as cellulose pre-treatment with tailored properties. N2 atmosphere is suitable for cleaning of cellulose surface, NH3 atmosphere for functionalization with amine and amide groups, and air atmosphere for increase or decrease of wettability, depending on exposure time.

Preparation of surfaces of composite samples for tip based micro-analyses using ion beam milling

Ion beam milling, as a method of surface design for tip analytical techniques, was explored. A sample of clay, embedded in a resin, was treated by the ion beam and allowed AFM (a typical tip technique) to be successfully applied. The method is suitable for advanced tip analyses based on AFM, like TERS or SNOM, and for samples that are not possible to prepare by standard mechanical methods. The approach can be useful for characterisation of the surfaces of many different types of materials in versatile applications such as catalysis, corrosion science or advanced material characterisation.

Reaction parameters of in situ silver chloride precipitation on cellulose fibres

In the present work, non-woven, non-regenerated cellulose wound dressing was subjected to in situ silver (Ag) deposition in the form of silver chloride (AgCl) under various reaction conditions. The studied reaction parameters were as follows: time, temperature, and reactants´ concentration. AgCl was bound on the cellulose via two-step process. Firstly, the silver ions (Ag+) were attracted to cellulose in the solution of silver nitrate (AgNO3). Secondly, Ag+ were precipitated directly on the cellulose by immersing the samples into the solution of sodium chloride (NaCl). The prepared samples were examined on the amount of bound and released Ag, and the release was studied both in water and in simulated body fluids. The reaction parameters significantly affected the amount of bound and released Ag, the difference of released Ag was as high as 75%. The key parameter in the process was reactants´ concentration. Non-regenerated cellulose modified with AgCl was antibacterially active.

Antimicrobial and optical properties of PET chemically modified and grafted with borane compounds

Polyethylene terephthalate (PET) foils were activated with piranha solution and grafted with selected amino compounds (cysteamine, ethylenediamine or chitosan) and then with borane compounds. Changes in their surface properties after particular modification steps were examined using electrokinetic analysis, X-ray photoelectron spectroscopy (XPS), goniometry and UV-vis spectroscopy. Several tests showed that the presence of some amino compounds and one borane cluster significantly improved the antimicrobial properties of the composites investigated. In particular, they exhibited strong antibacterial activity against Staphylococcus epidermidis but only weak activity against Escherichia coli. The samples modified with amino compounds and subsequently with borane clusters were luminescent under UV lamp irradiation. Therefore, the nanocomposites consisting of (cheap) polymer and (more expensive) borane could be used in luminophore development, medicine or environmental protection.

Deposition of thin metal layers on chitosan films

ABSTRACT The presented work is focused on preparation of chitosan films which were modified by plasma treatment and sputtering of silver nanoparticles (AgNPs) which made silver layers. The films were doped with AgNPs for enhancement of antibacterial properties. The presence of AgNPs was studied by X-ray photoelectron spectroscopy. Wettability and surface morphology of the films were evaluated. Antibacterial activity of solid films with AgNPs was tested by drip test on two bacterial strains, Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli. The films exhibited strong antibacterial activity against both bacterial strains. Solid films were dissolved and analyzed by transmission electron microscopy. Concentration of the AgNPs released into the solution during dissolution was studied by atomic absorption spectroscopy. The presence of AgNPs was confirmed both in the solid films and in the solutions by the above mentioned methods. Our research was aiming on use of these films in medicine as a new type of wound dressing with antibacterial properties.

Surface Structure and Cells Adhesion on Doped Polyethylene

The properties of polyethylene doped with Ca2+ salt of oxidized cellulose was studied by different techniques. FTIR spectroscopy was used for the determination of crystalline phase in polymer film, surface wettability was determined by standard goniometry and surface morphology was examined by SEM microscopy. Adhesion of mouse 3T3 fibroblasts on the doped polymer was studied in vitro. It was found that the polyethylene doped with the cellulose derivative can be sterilized in boiling water. The number and homogeneity of adhering cells were shown to depend on the surface wettability and morphology.

Surface Modification of Hydrogels and Cell Adhesion

Polymer hydrogels have many different functions in the field of tissue engineering and medicine. Modification of 2-hydroxy-ethyl-methacrylate (HEMA) and 2-ethyl-oxy-ethylmethacrylate (EOEMA) by plasma treatment performed in Ar atmosphere at RT for 0-400 s was studied using different techniques. Sample ablation was determined by gravimetry, surface wettability and aging by goniometry, chemical structure by FTIR spectroscopy and surface morphology by AFM microscopy. The plasma modification changes the sample surface morphology. In vitro cultivation shows that the plasma treatment changes the proliferation of human LEP cells.