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1.
Energy demand distribution and environmental impact assessment of chitosan production from shrimp shells
Filipa A. Vicente, Robert Hren, Uroš Novak, Lidija Čuček, Blaž Likozar, Annamaria Vujanović, 2024, izvirni znanstveni članek

Opis: Step towards resilience and sustainability through exploring renewable biomass and waste streams to produce higher-added value products and energy is among key aspects for closing the loops, saving resources, and reducing the resource and emission footprints. In that respective, crustacean shells waste can offer rich spectre of valuable compounds such as proteins, chitin, carotenoids. This waste is produced in large quantities worldwide, thus allowing for commercial valorisation. An overview of technologies is undertaken for more sustainable and environmentally friendly chitosan production via chitin isolation and conversion and compared to the conventional processes. Furthermore, an assessment of the environmental burden and energy demand distribution for conventional and more sustainable alternative processes was performed, based on lab-scale experimental data. Three different chitin extraction routes and three distinct chitosan conversion processes were considered and compared for their greenhouse gas footprint, abiotic depletion, acidification, eutrophication and other potentials. Finally, the energy demand distribution was analysed considering electricity production patterns from three European countries, Slovenia, Portugal and Norway. The results showed that alternatives 3-A and 3-B (conventional eco-solvents - conventional deacetylation with 40 % and 50 % NaOH) generate the lowest environmental burden (184 g CO2 eq./g chitosan). Electricity was the main hotspot of the processes, used either for extraction, plasma treatment or deacetylation. The sensitivity analysis proved that the Norwegian electricity mix has the lowest environmental impact (4.2 g CO2 eq./g chitosan). This study highlights the impact of blue biorefineries by transforming marine waste to valuable biopolymers such as chitin and chitosan.
Ključne besede: shrimp shells waste, blue biorefinery, value-added products, chitosan, sustainable production, comparative environmental assessment
Objavljeno v DKUM: 08.01.2025; Ogledov: 1; Prenosov: 1
.pdf Celotno besedilo (2,16 MB)

2.
Nanodelci hitozana kot potencialni protimikrobni premaz
Zdenka Peršin Fratnik, Uroš Maver, Metod Kolar, Olivera Šauperl, Lidija Fras Zemljič, Boštjan Vihar, 2024, izvirni znanstveni članek

Opis: Namen študije je bil ugotoviti protimikrobno učinkovitost hitozanskih nanodelcev v primerjavi s hitozansko raztopino in sled temu njihovo učinkovito rabo na medicinskih tekstilnih materialih.
Ključne besede: chitosan, nanoparticles, antimicrobial activity, coatings, medical textile materials
Objavljeno v DKUM: 07.01.2025; Ogledov: 0; Prenosov: 17
.pdf Celotno besedilo (903,83 KB)
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3.
A method for the immobilization of chitosan onto urinary catheters
Alenka Vesel, Nina Recek, Rok Zaplotnik, Albert Kurinčič, Katja Kuzmič, Lidija Fras Zemljič, 2022, izvirni znanstveni članek

Opis: A method for the immobilization of an antibacterial chitosan coating to polymeric urinary medical catheters is presented. The method comprises a two-step plasma-treatment procedure, followed by the deposition of chitosan from the water solution. In the first plasma step, the urinary catheter is treated with vacuum-ultraviolet radiation to break bonds in the polymer surface film and create dangling bonds, which are occupied by hydrogen atoms. In the second plasma step, polymeric catheters are treated with atomic oxygen to form oxygen-containing surface functional groups acting as binding sites for chitosan. The presence of oxygen functional groups also causes a transformation of the hydrophobic polymer surface to hydrophilic, thus enabling uniform wetting and improved adsorption of the chitosan coating. The wettability was measured by the sessile-drop method, while the surface composition and structure were measured by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Non-treated samples did not exhibit successful chitosan immobilization. The effect of plasma treatment on immobilization was explained by noncovalent interactions such as electrostatic interactions and hydrogen bonds.
Ključne besede: polymer, chitosan immobilization, adhesion, plasma-surface modification, biopolymers
Objavljeno v DKUM: 05.12.2024; Ogledov: 0; Prenosov: 2
.pdf Celotno besedilo (6,47 MB)
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4.
Films based on TEMPO-oxidized chitosan nanoparticles: Obtaining and potential application as wound dressings
Matea Korica, Katarina Mihajlovski, Tamilselvan Mohan, Mirjana M. Kostić, 2024, izvirni znanstveni članek

Opis: A series of novel films based on TEMPO-oxidized chitosan nanoparticles were prepared by casting method. Fourier transform infrared spectroscopy (FTIR) was employed to ascertain the chemical structure of TEMPOoxidized chitosan. The surface morphology of the TEMPO-oxidized chitosan nanoparticles was analyzed by atomic force microscopy (AFM). The physicochemical (area density, thickness, iodine sorption, roughness), functional (moisture sorption, liquid absorption capacity, weight loss upon contact with the liquid, and water vapor transmission rate), antibacterial, and antioxidant properties of films based on TEMPO-oxidized chitosan nanoparticles were also investigated. The physicochemical properties of the films varied widely: area density ranged from 77.83 ± 0.06 to184.46 ± 0.05 mg/cm2 , thickness varied between 80.5 ± 1.6 and 200.5 ± 1.6 μm, iodine sorption spanned from 333.7 ± 2.1 to166.4 ± 2.2 mg I2/g, and roughness ranged from 4.1 ± 0.2 to 5.6 ± 0.3 nm. Similarly, the functional properties also varied significantly: moisture sorption ranged from 4.76 ± 0.03 to 9.62 ± 0.11 %, liquid absorption capacity was between 129.04 ± 0.24 and 159.33 ± 0.73 % after 24 h, weight loss upon contact with the liquid varied between 31.06 ± 0.35 and 45.88 ± 0.58 % after 24 h and water vapor transmission rate ranged from 1220.10 ± 2.91to1407.77 ± 5.22 g/m2 day. Despite the wide variations in physicochemical and functional properties, all films showed maximum bacterial reduction of Staphylococcus aureus and Escherichia coli, although they exhibited low antioxidant activity. The results suggest that the films could be effectively utilized as antibacterial wound dressings.
Ključne besede: TEMPO-oxidized chitosan nanoparticles, films, antibacterial activity, wound dressings
Objavljeno v DKUM: 11.09.2024; Ogledov: 56; Prenosov: 44
.pdf Celotno besedilo (4,92 MB)
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5.
Influence of cross-linkers on the wash resistance of chitosan-functionalized polyester fabrics
Tanja Pušić, Tea Bušac, Julija Volmajer Valh, 2024, izvirni znanstveni članek

Opis: This study investigates the wash resistance of polyester fabrics functionalized with chitosan, a biopolymer known for its biocompatibility, non-toxicity, biodegradability and environmentally friendly properties. The interaction of chitosan with synthetic polymers, such as polyester, often requires surface treatment due to the weak natural affinity between the two materials. To improve the interaction and stability of chitosan on polyester, alkaline hydrolysis of the polyester fabric was used as a surface treatment method. The effectiveness of using cross-linking agents 1,2,3,4-butane tetracarboxylic acid (BTCA) and hydroxyethyl methacrylate (HEMA) in combination with ammonium persulphate (APS) to improve the stability of chitosan on polyester during washing was investigated. The wash resistance of polyester fabrics functionalized with chitosan was tested after 1, 5 and 10 washes with a standard ECE detergent. Staining tests were carried out to evaluate the retention of chitosan on the fabric. The results showed that polyester fabrics functionalized with chitosan without cross-linkers exhibited better wash resistance than the fabrics treated with crosslinkers.
Ključne besede: polyster, functionalization, chitosan, cross-linkers, stability, washing
Objavljeno v DKUM: 10.09.2024; Ogledov: 55; Prenosov: 13
.pdf Celotno besedilo (17,25 MB)
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6.
Covalent modification of chitosan surfaces with a sugar amino acid and lysine analogues
Tobias Dorn, Matjaž Finšgar, Karin Stana-Kleinschek, Tobias Alexander Steindorfer, Martin Simon Thonhofer, Tanja Wrodnigg, Rupert Kargl, 2024, izvirni znanstveni članek

Opis: This work explores the modifcation and characterization of chitosan thin flms as a model for functionalized polysaccharide interfaces. The solid–liquid interface of oligo- and polysaccharides is crucial for various biological processes such as cell adhesion and recognition. By covalent surface modifcation of the chitosan via amide formation with diferent small molecules containing carboxylic acids, e.g. specially designed glycoside hydrolase inhibitors, interactions with biomolecules and living cells could potentially be controlled in the future. As a frst step towards this aim, three fuorescent compounds were conjugated onto nanometric chitosan thin flms. The layers were analysed by fuorescence spectroscopy, X-ray photoelectron spectroscopy, time-of-fight secondary ion mass spectrometry, and atomic force microscopy, to proof the covalent attachment of the target molecules. By this analysis, a uniform and chemically stable covalent attachment of the target molecules on the chitosan thin flms could be demonstrated under various conditions. This publication serves as a proof-of-concept-study for further biofunctionalization, pattering, and interaction studies involving polysaccharide interfaces, glycosidase inhibitors, proteins, or living cells.
Ključne besede: carbohydrates, fluorescence spectroscopy, amino acid, chitosan, thin flm modifcation, C-Glycosides
Objavljeno v DKUM: 07.08.2024; Ogledov: 127; Prenosov: 15
.pdf Celotno besedilo (2,03 MB)

7.
Exploring chitosan-plant extract bilayer coatings: Advancements in active food packaging via polypropylene modification
Saša Kaloper, Olivija Plohl, Sonja Smole Možina, Alenka Vesel, Vida Šimat, Lidija Fras Zemljič, 2024, izvirni znanstveni članek

Opis: UV-ozone activated polypropylene (PP) food films were subjected to a novel bilayer coating process involving primary or quaternary chitosan (CH/QCH) as the first layer and natural extracts from juniper needles (Juniperus oxycedrus; JUN) or blackberry leaves (Rubus fruticosus; BBL) as the second layer. This innovative approach aims to redefine active packaging (AP) development. Through a detailed analysis by surface characterization and bioactivity assessments (i.e., antioxidant and antimicrobial functionalities), we evaluated different coating combinations. Furthermore, we investigated the stability and barrier characteristics inherent in these coatings. The confirmed deposition, coupled with a comprehensive characterization of their composition and morphology, underscored the efficacy of the coatings. Our investigation included wettability assessment via contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), which revealed substantial enhancements in surface concentrations of elements and functional groups of CH, QCH, JUN, and BBL. Scanning electron microscopy (SEM) unveiled the coatings' heterogeneity, while time-of-flight secondary ion mass spectrometry (ToF-SIMS) and CA profiling showed moderately compact bilayers on PP, providing active species on the hydrophilic surface, respectively. The coatings significantly reduced the oxygen permeability. Additionally, single-layer depositions of CH and QCH remained below the overall migration limit (OML). Remarkably, the coatings exhibited robust antioxidative properties due to plant extracts and exceptional antimicrobial activity against S. aureus, attributed to QCH. These findings underscore the pivotal role of film surface properties in governing bioactive characteristics and offer a promising pathway for enhancing food packaging functionality.
Ključne besede: chitosan, plant extracts, polypropylene, active packaging, surface characterization, bioactivity
Objavljeno v DKUM: 27.05.2024; Ogledov: 241; Prenosov: 18
.pdf Celotno besedilo (4,75 MB)
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8.
Slot‑die coating of cellulose nanocrystals and chitosan for improved barrier properties of paper
Ylenia Ruberto, Vera Vivod, Janja Juhant Grkman, Gregor Lavrič, Claudia Graiff, Vanja Kokol, 2024, izvirni znanstveni članek

Opis: Cellulose nanocrystals (CNCs) and chitosan (Cht) have been studied extensively for oxygen and water vapour barrier coatings in biodegradable, compostable or recyclable paper packaging. However, rare studies have been performed by using scalable, inexpensive, and fast continuous slot-die coating processes, and none yet in combination with fast' and high-throughput near-infrared (NIR) light energy drying. In this frame, we studied the feasibility of a moderately concentrated (11 wt%) anionic CNC and (2 wt%) cationic Cht coating (both containing 20 wt% sorbitol related to the weight of CNC/Cht), by using plain and pigment pre-treated papers. The effect of coating parameters (injection speed, dry thickness settings) were investigated on coating quantity (dry weight, thickness) and homogeneity (coverage), papers' structure (thickness, grammage, density), whiteness, surface wettability, barrier (air, oxygen and water vapour) properties and adhesion (surface strength). The coating homogeneity was dependent primarily on the suspensions' viscosity, and secondarily on the applied coating parameters, whereby CNCs could be applied at 1–2 times higher injection speeds (up to 80 mL/min) and versatile coating weights, but required a relatively longer time to dry. The CNCs thus exhibited outstanding air (4.2–1.5 nm/Pa s) and oxygen (2.7–1.1 cm3 mm/m2 d kPa) barrier performance at 50% RH and 22–33 g/m2 deposition, whereas on top deposited Cht (3–4 g/m2) reduced its wetting time and improved the water vapour barrier (0.23–0.28 g mm/m2 d Pa). The balanced barrier properties were achieved due to the polar characteristic of CNCs, the hydrophobic nature of Cht and the quantity of the applied bilayer coating that can provide sustainable paper-based packaging.
Ključne besede: paper, nanocellulose, chitosan, slot‑die coating, near-infrared (NIR) drying, barrier properties
Objavljeno v DKUM: 06.05.2024; Ogledov: 227; Prenosov: 12
.pdf Celotno besedilo (1,59 MB)
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9.
10.
Bioactive functional nanolayers of chitosan-lysine surfactant with single- and mixed-protein-repellent and antibiofilm properties for medical implants
Urban Ajdnik, Lidija Fras Zemljič, Olivija Plohl, Lourdes Pérez, Janja Trček, Matej Bračič, Tamilselvan Mohan, 2021, izvirni znanstveni članek

Opis: Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption arethe prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer apromising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to researchand develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties incontact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-freepolyelectrolyte−surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionicsurfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria.We successfully introduced the PESC as bioactive functional nanolayers on the“model”and“real”polydimethylsiloxane (PDMS)surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly depositednanolayers (thickness: 44−61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serumalbumin,fibrinogen, andγ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartzcrystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ:−19 to−30mV at pH 7.4), water content (1628−1810 ng cm−2), and hydration (low viscosity and elastic shear modulus) correlated with themass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed thatthe charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcusaureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatingswith simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leadingto a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents).
Ključne besede: silicone implants, protein-repellent, antimicrobial, chitosan, lysine, bioactive coatings, adsorption, QCM-D
Objavljeno v DKUM: 15.04.2024; Ogledov: 266; Prenosov: 16
.pdf Celotno besedilo (4,24 MB)
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