Lidija Fras Zemljič

Improvement of chitosan adsorption onto cellulosic fabrics by plasma treatment.

Oxygen plasma treatment was applied in order to improve the adsorption of chitosan onto viscose fabric. Modification of the surface and adsorption of chitosan was monitored by determination of XPS spectra, determination of contact angles from rates of water imbibition, and conductometric titration. The plasma treatment resulted in hydrophilization of the surfaces through oxidation. The hydrophilic surfaces were stable for at least 24 h. The treatment also yielded binding sites that resulted in over 20% increase of the amount of chitosan adsorbed over that adsorbed on nontreated fabric. Layers of chitosan adsorbed after plasma treatment were substantially more active as antimicrobial agents than those on nontreated surfaces.

Characterization of amino groups for cotton fibers coated with chitosan

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.

Antimicrobial and antioxidant functionalization of viscose fabric using chitosan–curcumin formulations:

The purpose of this work was to develop new additive combinations between chitosan and curcumin in solutions as a fiber-coating. Diverse additive combinations between chitosan and curcumin in solutions were adsorbed onto viscose fabrics in order to reach the essential antimicrobial and antioxidant functionalization for medical textiles. The goal of this paper was to examine the adsorption of these two compounds as an additive formulation on viscose textile material as well as to analyze the desorptions of both substances from the fabric surface. Finally, the antimicrobial and antioxidant properties of viscose fabrics functionalized by chitosan–curcumin formulations were respectively examined. Curcumin as an adsorbate for textiles in combination with chitosan represents an added-value because of its anti-oxidative properties, and showing the potential to enhance existing antimicrobial performance of chitosan when applied using the preferred procedure.

One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate

Correction for ‘One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate’ by Sergiu Coseri et al., RSC Adv., 2015, 5, 85889–85897.

Viscose material functionalized by chitosan as a potential treatment in gynecology

This paper presents the functionalization of viscose cellulose material with chitosan for potential application in cellulose tampons for everyday use that would not display negative side effects, such as irritation of the vaginal wall, toxic shock syndrome, etc. The technological parameters of tampons, amount of amino groups due to chitosan adsorption, and the antimicrobial activity of the tampons were analyzed. Aqueous chitosan solutions buffered with lactic or acetic acid were sprayed on viscose fibers, from which tampons were prepared and dried at 40°C in an air chamber or at room temperature. Adsorption of chitosan was determined by conductometric titration. The absorptivity and antimicrobial activity of the tampons were determined by standard methods. It is concluded that tampons prepared in this way possess the following new properties: maintenance of the physiological pH of the vagina together with its moisturizing effect, good technical properties, and antimycotic, as well as antibacterial, activity.

A novel synergistic formulation between a cationic surfactant from lysine and hyaluronic acid as an antimicrobial coating for advanced cellulose materials

Abstract In this investigation, a novel coating for viscose fabric surface modification was developed using a synergistic formulation between a natural antimicrobial cationic surfactant from lysine (MKM) and a biopolymer hyaluronic acid (HA). The interaction between MKM and HA in aqueous solutions, as well as the interactions between their synergistic formulation (HA-MKM) and viscose fabric (CV) were studied using pH-potentiometric titrations’, turbidity measurements, the Kjeldahl method for the determination of nitrogen amounts, attenuated total reflectance fourier transform infrared spectroscopy, and scanning electron microscopy. The hydrophilic and antimicrobial properties of the functionalised CV were examined in order to evaluate its usages for medical applications. The results of the interaction studies showed that MKM and HA interact with each other by forming a precipitate when the binding sites of HA are saturated. The precipitate has a slightly positive charge at neutral pH due to excess binding of the MKM to HA. The excess positive charge was also detected on CV coated with HA-MKM. This was proven to be very beneficial for the antimicrobial properties of the functionalised CV. The antimicrobial tests showed exceptional antimicrobial activity of the functionalised CV against Escherichia Coli, StaphylococcusAureus, StreptococcusAgalactiae, Candida Albicans, and Candida Glabrata, making the CV fabric highly interesting for potential use in medicine.

Interaction of Sodium Hyaluronate with a Biocompatible Cationic Surfactant from Lysine: A Binding Study

Mixtures of natural and biodegradable surfactants and ionic polysaccharides have attracted considerable research interest in recent years because they prosper as antimicrobial materials for medical applications. In the present work, interactions between the lysine-derived biocompatible cationic surfactant N(ε)-myristoyl-lysine methyl ester, abbreviated as MKM, and the sodium salt of hyaluronic acid (NaHA) are investigated in aqueous media by potentiometric titrations using the surfactant-sensitive electrode and pyrene-based fluorescence spectroscopy. The critical micelle concentration in pure surfactant solutions and the critical association concentration in the presence of NaHA are determined based on their dependence on the added electrolyte (NaCl) concentration. The equilibrium between the protonated (charged) and deprotonated (neutral) forms of MKM is proposed to explain the anomalous binding isotherms observed in the presence of the polyelectrolyte. The explanation is supported by theoretical model calculations of the mixed-micelle equilibrium and the competitive binding of the two MKM forms to the surface of the electrode membrane. It is suggested that the presence of even small amounts of the deprotonated form can strongly influence the measured electrode response. Such ionic-nonionic surfactant mixtures are a special case of mixed surfactant systems where the amount of the nonionic component cannot be varied independently as was the case for some of the earlier studies.

Characterization of viscose fibers modified with 6-deoxy-6-amino cellulose sulfate

Cellulose viscose fibres were functionalized by novel amino cellulose sulfates (ACS), namely 6-deoxy-6-(ω-aminoethyl) amino cellulose-2,3(6)-O-sulfate (AECS), and 6-deoxy-6-(2-(bis-N′,N′-(2-aminoethyl)aminoethyl)) amino cellulose-2,3(6)-O-sulfate (BAECS). In this way an amphoteric characteristics were introduced onto cellulose viscose fibers which is extremely important by fiber applications. Whilst cellulose fibers possess only negligible carboxyl groups’ content, the coating of fibers by AECS and BAECS, respectively, introduces new functional groups to the fibers; as positively-charged amino groups and negatively-charged sulfate groups. The typical functional groups within the non-coated fibers, as well in the ACS-coated fibers, were characterized by means of X-ray photoelectron spectroscopy, conductometric-, potentiometric and polyelectrolyte titrations, as well as conventionally by the spectroscopic methylene-blue method. The electro-kinetic behavior was evaluated by measuring the zeta-potential of the fibers as a function of pH. The amounts of the positive-charges (introduced protonated amino groups) determined by potentiometric titration agreed with the amounts of the positive charges determined by conductometric titration. The total amounts of negatively-charged fiber groups (sulfate and carboxyl) determined by polyelectrolyte titration were 38.8 and 32.1 mMol kg−1 for AECS-Vis and BAECS-Vis, respectively, and these results were in accordance with the conventional methylene-blue method.

Chitosan nanoparticles as a potential drug delivery system attached to viscose cellulose fibers

Chitosan and its water-soluble N,N,N-trimethyl derivative were attached to cellulose fibers in the form of nanoparticle dispersions. The attachment of the chitosan nanoparticles to the fiber surface was studied by evaluation of the quantity of chitosan amino groups using a conventional spectrophotometric method supported by X-ray photoelectron spectroscopy. The desorption kinetics of the chitosan nanoparticles from the fiber surface was also examined indirectly by the spectrophotometric method. Additionally, a model drug was incorporated into the optimal chitosan nanoparticles for subsequent attachment to fibers to create a potential fibrous drug delivery system aimed at gynecological use, i.e., tampons as antimicrobial agents themselves or as drug reservoirs.

Chemical modification and characterization of poly(ethylene terephthalate) surfaces for collagen immobilization

AbstractThe functionalization of poly(ethylene terephthalate) (PET) surface films by reactions with multifunctional amines such as triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) was investigated. For the functionalization of PET films surface we used a new way of treatment, a “sandwich model”. Physical-chemical properties of functionalized PET films were analysed. Qualitative and quantitative determination of the introduced amine groups were examined by means of Fourier Transform Infrared Attenuated Total Reflexion (FTIR — ATR), X-ray photoelectron spectroscopy (XPS), and potentiometric titration. Gained wetting properties were determined by using contact angle measurements and thoroughly analysed by acid-base approach. In addition, surface topography was investigated by atomic force microscopy (AFM). The amount of the introduced amino groups after TETA incorporation has been found to be two times higher as compared to TEPA. Wetting properties were significantly improved after aminolysis. Surface free energy was higher for PET — TETA treated film than that observed for PET — TEPA treated which is in accordance with titration results. The collagen immobilization onto PET treated films was evidenced by using AFM and subsequently by using XPS.