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1.
Cellulose fibres functionalised by chitosan : characterization and application
Simona Strnad, Olivera Šauperl, Lidija Fras Zemljič, 2010, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Ključne besede: cellulose fibers, medical applications, chitosan, antimicrobic properties
Objavljeno: 31.05.2012; Ogledov: 965; Prenosov: 13
URL Povezava na celotno besedilo

2.
Adsorption and antibacterial activity of soluble and precipitated chitosan on cellulose viscose fibers
Lidija Fras Zemljič, Tijana Ristić, Tina Tkavc, 2012, izvirni znanstveni članek

Opis: The aim and novelty of this work was to compare the adsorption of totally-soluble chitosan (acidic solution) against the adsorption of precipitated chitosan, onto cellulose fibers. The influences of both these chitosan-adsorption procedures on a final amino groupćs content in functionalized cellulose fibers were studied, using potentiometric titration and the conventional spectrophotometric C.I. Acid Orange 7 method. Surface modification and adsorption of chitosan were, in addition, monitored by determining XPS spectra. The antimicrobial activities of both chitosan- functionalised cellulose fibers were examined, in regard to pathogen bacteria and fungus.
Ključne besede: functionalized viscose, chitosan solution, precipitates, potentiometric titration, spectrophotometry, antimicrobial activity
Objavljeno: 01.06.2012; Ogledov: 1345; Prenosov: 212
.pdf Celotno besedilo (372,02 KB)
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3.
Characterization of amino groups for cotton fibers coated with chitosan
Lidija Fras Zemljič, Simona Strnad, Olivera Šauperl, Karin Stana-Kleinschek, 2009, izvirni znanstveni članek

Opis: The adsorption of chitosan onto cellulose cotton fibers introduces antimicrobial properties, mainly created by the amount and location of amino groups. Therefore, it is important to be able to analyze both parameters, especially in a heterogeneous system, namely cotton fibers coated with chitosan. In this research, three different analytical techniques were applied to determine amino groups of cotton fibers coated with chitosan. The number of positively charged groups was determined indirectly by the spectrophotometric method using Acid Orange 7 dye, and the use of polyelectrolyte titration. In addition, the chemical surface composition regarding non-modified, as well as modified cotton fibers (coated with chitosan), was investigated using X-ray Photoelectron Spectroscopy (XPS). The results from a combination of these methods show that chitosan treatment introduces more than 14 mmol/kg of accessible amino groups onto the cotton fibers. The results were in good agreement with the results of XPS. The use of spectrophotometric and titration methods in combination with XPS appears to be a very useful tool for identifying the formation of amino groups in modified cotton fibers and their surfaces.
Ključne besede: cotton, cellulose, oxidation, chitosan, amino-groups, titration, XPS
Objavljeno: 01.06.2012; Ogledov: 1023; Prenosov: 99
URL Povezava na celotno besedilo

4.
Adsorption of fucoidan and chitosan sulfate on chitosan modified PET films monitored by QCM-D
Tea Indest, Janne Laine, Leena Sisko Johansson, Karin Stana-Kleinschek, Simona Strnad, Renate Dworczak, Volker Ribitsch, 2009, izvirni znanstveni članek

Opis: The adsorption behavior of fucoidan as well as chitosan derivatives (chitosan sulfate) on poly(ethylene terephthalate) (PET) model film surface was studied using the quartz crystal microbalance technique. These systems were chosen for this study due to their promising biocompatible properties. Moreover, fucoidan and chitosan sulfate have promising anticoagulant properties and represent an alternative to heparin treatment of vascular grafts. As a first step, PET foils were activated by alkaline hydrolysis to increase their hydrophilicity. From these foils, model PET films were prepared by the spin coating technique on a silica quartz crystal. The selected polysaccharides (chitosan, fucoidan, and chitosan sulfate) were adsorbed from aqueous solutions on the PET surfaces. The adsorption was monitored using a quartz crystal microbalance with a dissipation unit. The surface chemistry and morphology of the chitosan/fucoidan or chitosan/chitosan sulfate coated PET-H films was analyzed using XPS and AFM. It was found that chitosan/fucoidan films were thinner and more compressed, while in the case of chitosan/chitosansulfate, large amounts of chitosan sulfate were adsorbed, indicating a loose and thick adsorbed film.
Ključne besede: PET films, fucoidan, chitosan sulfate, adsorption, anticoagulant properties
Objavljeno: 01.06.2012; Ogledov: 1102; Prenosov: 50
URL Povezava na celotno besedilo

5.
Antimicrobial medical textiles based on chitosan nanoparticles for gynaecological treatment
Tijana Ristić, 2014, doktorska disertacija

Opis: The aim of this dissertation was to develop a novel medical tampon for alternative gynaecological treatment using chitosan nanoparticles as an antimicrobial agent or as a drug delivery system. For this purpose viscose tampon band was used and functionalized with chitosan and trimethyl chitosan nanoparticles. A comprehensive of interactions between chitosan and cellulose as well as characterization of prepared materials were done. At the beginning, chitosan (CS) and trimethyl chitosan (TMC) solutions, as well as nanoparticles synthesised by ionic gelation were studied. Their characterization was focused on determining the charge and antimicrobial properties against common pathogenic microorganism. The influence of cationic charge on the inhibition of microbial growth was confirmed. Since CS and TMC solutions and nanoparticles dispersions exhibited antibacterial activity against Lactobacillus, a detailed investigation in chitosan’s antimicrobial mode of action was performed using a novel diffusion nuclear magnetic resonance (D-NMR). D-NMR allowed the monitoring of intra- and extracellular water exchange from the cells indicating the membrane alteration and leakage of intracellular constituencies. Further, in order to study the adsorption phenomena and molecular interactions between CS/TMC (solution or nanoparticles) and cellulose material, model cellulose surfaces were used, and adsorption was studied by quartz crystal microbalance with dissipation. CS and TMC were favourably deposited onto cellulose model surface at higher ionic strength, higher pH values, i.e. factors causing lower solubility, where the presence of electrostatic interactions was negligible and non-electrostatic interactions were dominant. The knowledge gained from the model surfaces was extremely helpful in characterization of real systems, i.e. functionalized cellulose fibres and for understanding the obtained results. Immobilization of CS and TMC (in the form of solution and/or nanoparticles) onto cellulose viscose fibres was confirmed with several analytical methods. The attachment of chitosan onto fibres was reversible, as endorsed with desorption studies mimicking the conditions of vaginal usage. Evaluation of antimicrobial properties was performed using two different techniques, both revealing a high inhibition of the tested microorganism. In addition, Lactobacillus susceptibility testing has shown that chitosan-coated fibres do not have any negative influence on the resident microbiota. Assessment of in-vitro cytotoxicity demonstrated that samples do not cause a cytotoxic effect in direct contact. Additionally, model drug was incorporated into chitosan nanoparticles and subsequently attached onto fibres in order to create modern, vaginal drug delivery systems. Antimicrobial medical textiles investigated in the scope of this dissertation show the potential for their exploitation in gynaecological field as preventive or curative treatment without triggering any adverse effects for the user.
Ključne besede: chitosan, N, N, N-trimethyl chitosan, nanoparticles, antimicrobial activity, cellulose model films, regenerated cellulose fibres, diffusion nuclear magnetic resonance, quartz crystal microbalance, vaginal infections, drug delivery systems, cytotoxicity
Objavljeno: 13.02.2014; Ogledov: 1941; Prenosov: 75
URL Povezava na celotno besedilo

6.
Manipulation of chitosan binding on the polyethylene terephthalate (PET) surface and study of coatings on poultry meat shelf life-time
Tina Tkavc, 2014, doktorska disertacija

Opis: The aim of this study was to activate inert PET surfaces in order to introduce the surfaces’ carboxyl groups and to obtain its hydrophilic character, which was important for the chitosan bonding to it. Films where chitosan was attached to the PET could be used as active packaging material for food like fresh poultry meat. For PET activation two advanced and environmentally friendly techniques were used: 1) O2 plasma activation; and 2) CO2 plasma activation. Differently treated PET foils deposited on Au quartz crystals (model studies - adsorption and desorption) and real films were characterized. Later on, real films were studied in the terms of carboxylic/amino group content, hydrophobic/hydrophilic character, surface composition and adsorption/desorption of chitosan onto/from the surface. Results clearly showed that the use of both surfaces’ activation processes increased the ability of PET foils to adsorb chitosan, but CO2 plasma gave a higher concentration of carboxyl groups on the PET surface and consequently, due to the chemical bonding the chitosan layers were more stable. Even though CO2 plasma pre-treated PET foils gave better results during the experimental work, we could not avoid layer by layer adhesion of chitosan which resulted in non-bound molecules. Pre-treated foils and with chitosan functionalized foils were tested preliminarily with ASTME E1 (2002) microbiological tests. Functionalized CO2 plasma pre-treated foils gave the broadest spectra of antimicrobial activity, and therefore they were chosen for further microbiological analyses, where chitosan`s influence on inoculated poultry models towards selected standard strains, typical for poultry meat, was being tested. By determining the MIC (minimal inhibitory concentration) for selected microorganisms we have proven, that chitosan possesses antimicrobial properties at low concentrations. During the transfer of the experiment to a larger scale (food models, which are a very complex environment), it has been shown that on PET bonded chitosan did not have the inhibitory effect to that extent, with the exception of Staphylococcus aureus, as was expected. Similar results were expressed using both these methods: Colony count technique and real-time PCR. In the end, the organoleptic properties of the chicken models exposed to foils have shown that chitosan changes the color and taste of meat immediately after exposure, but samples were staying edible longer. Therefore, functionalized PET, which has an inhibitory influence towards variety of microorganisms, may be applied as an active packaging system for poultry meat after some optimization of the coating procedure in binding chitosan onto the PET surfaces.
Ključne besede: PET/chitosan/antimicrobial packaging/adsorption-desorption kinetics/microbiological tests
Objavljeno: 22.10.2014; Ogledov: 1301; Prenosov: 124
.pdf Celotno besedilo (3,65 MB)

7.
Viscose functionalisation with a combination of chitosan/BTCA using microwaves
Olivera Šauperl, Julija Volmajer Valh, 2013, izvirni znanstveni članek

Opis: Improved hygiene and health care standards have a great impact on the development of hygiene and health care products. For this purpose, viscose is a very popular substrate. One of the most promising anti-microbial compounds of modern times is chitosan. The anti-microbial action of this polysaccharide depends on the amino group amount, which is crucial for ensuring the effectiveness of anti-microbial treated material. In textile finishing, 1,2,3,4-buthanetetracarboxylic acid (BTCA) is usually used as a non-formaldehyde crease-resistant reagent. But, on the other hand, the negatively charged carboxyl groups of BTCA can be explored as additional binding sites for positively-charged protonated amino groups of chitosan. When using microwaves, polar materials (e.g. chitosan) orient and reorient themselves according to the direction of the electro-magnetic field, which means that chitosan chain-bending may have taken place during the drying with microwaves. This could result in a higher specific surface of the chitosan and, consequently, in a higher proportion of available amino groups. It is concluded that the combination chitosan/BTCA supported by microwaves drying represents an ideal combination to increase the proportion of available amino groups.
Ključne besede: viskoza, protimikrobna zaščita, viscose, chitosan/BTCA, microwawes, Acid Orange VII, methylene blue, antimicrobial activity
Objavljeno: 10.07.2015; Ogledov: 654; Prenosov: 15
URL Povezava na celotno besedilo

8.
Chemical binding of chitosan and chitosan nanoparticles onto oxidized cellulose
Olivera Šauperl, Mirjana Kostić, Jovana Milanovic, Lidija Fras Zemljič, 2015, izvirni znanstveni članek

Opis: The aim of this study was to analyze binding of chitosan and chitosan nanoparticles onto cellulose via oxidized cellulose. The ability of chitosan and chitosan nanoparticles to be adsorbed onto surfaces was determined by the use of the XPS spectroscopy which provided information about chemical composition of the fiber surface. On the other hand, the gravimetric method was also used by which the amount of chitosan and chitosan nanoparticles bounded onto surface was calculated based on the difference in masses before and after functionalization. The most important was to study the influence of aldehyde groups on the stability of chitosan binding onto cellulose. Thus, desorption of chitosan/chitosan nanoparticles from the fiber surfaces was evaluated by the presence of total nitrogen (TN) in desorption bath as well as by polyelectrolyte titrations. Together with these two methods, desorption was evaluated also by gravimetric method, where the extent of desorption was evaluated on the basis of the differences in the masses of fibers before and after desorption. It is concluded that the chitosan and chitosan nanoparticles are more efficiently bounded onto oxidized cellulose in comparison with the non-oxidized (reference) ones. Despite the binding of the positively-charged amino groups with the negative groups of cellulose and consequently smaller amount of available/residual protonated amino groups that are responsible for bioactivity, such functionalized fibers are still specifically antimicrobial.
Ključne besede: cellulose, oxidized cellulose, oxidation, chitosan, chitosan nanoparticles, FTIR, XPS, antimicrobial functionalization
Objavljeno: 02.08.2017; Ogledov: 430; Prenosov: 250
.pdf Celotno besedilo (144,32 KB)
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9.
Synthesis comparison and characterization of chitosan-coated magnetic nanoparticles prepared with different methods
Gordana Hojnik Podrepšek, Željko Knez, Maja Leitgeb, 2014, izvirni znanstveni članek

Opis: In this study, magnetic maghemite nanoparticles were prepared with the coprecipitation method, due to its simplicity and productivity. Thereafter, chitosan-coated magnetic nanoparticles were synthesized with three different methods, the micro-emulsion process, the suspension cross-linking technique and the covalent binding. Subsequently, a comparison of the used methods was done using various analyses such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetry (TGA), differential scanning calorimetry (DSC), vibrating-sample magnetometry (VSM) and dynamic light scattering (DLS). The characterization results from Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) indicated a successful binding of chitosan on the magnetic nanoparticles. SEM pictures showed that spherical structured particles with an increased particle size were obtained as the chitosan layer around the particles was increased. Considering that the magnetic-separation technique has the advantages of rapidity, high efficiency, cost-effectiveness and lack of negative effect on the biological activity, these carriers may be applied in enzyme immobilization.
Ključne besede: magnetic nanoparticles, chitosan, surface functionalization
Objavljeno: 23.03.2017; Ogledov: 510; Prenosov: 53
.pdf Celotno besedilo (1022,83 KB)
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10.
Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applications
Matjaž Finšgar, Amra Perva-Uzunalić, Janja Stergar, Lidija Gradišnik, Uroš Maver, 2016, izvirni znanstveni članek

Opis: Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys.
Ključne besede: corrosion, corrosion resistance, chitosan, biocompatibility, biomaterials, biomedical materials, coatings, stainless steel
Objavljeno: 23.06.2017; Ogledov: 577; Prenosov: 179
.pdf Celotno besedilo (2,73 MB)
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