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Cellulose–chitosan functional biocomposites
Simona Strnad, Lidija Fras Zemljič, 2023, review article

Abstract: Here, we present a detailed review of recent research and achievements in the field of combining two extremely important polysaccharides; namely, cellulose and chitosan. The most important properties of the two polysaccharides are outlined, giving rise to the interest in their combination. We present various structures and forms of composite materials that have been developed recently. Thus, aerogels, hydrogels, films, foams, membranes, fibres, and nanofibres are discussed, alongside the main techniques for their fabrication, such as coextrusion, co-casting, electrospinning, coating, and adsorption. It is shown that the combination of bacterial cellulose with chitosan has recently gained increasing attention. This is particularly attractive, because both are representative of a biopolymer that is biodegradable and friendly to humans and the environment. The rising standard of living and growing environmental awareness are the driving forces for the development of these materials. In this review, we have shown that the field of combining these two extraordinary polysaccharides is an inexhaustible source of ideas and opportunities for the development of advanced functional materials.
Keywords: biocomposites, functional materials, cellulose–chitosan, fibers, films, hydrogels, nanofibers
Published in DKUM: 19.02.2024; Views: 43; Downloads: 1
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Razvoj novih funkcionalnih plastičnih filmov za različne produkte : magistrsko delo
Tanja Labohar, 2023, master's thesis

Abstract: Plastični materiali imajo velik pomen v pakirnem segmentu za pakiranje farmacevtskih, kozmetičnih in prehrambnih produktov, kjer želimo podaljšati rok trajanja živil. Vedno večje zavedanje podjetij in potrošnikov o negativnem vplivu petrokemijske plastike na okolje in povečano tveganje za zdravje, ki ga predstavljajo sintetični aditivi v plastični embalaži, so privedli do razvoja biorazgradljive aktivne embalaže. V magistrskem delu smo želeli razviti antioksidativne, protimikrobne in biorazgradljive funkcionalne plastične filme. Folije PLA smo funkcionalizirali s premazom iz formulacije ekstrakta brina in hitozana, ki smo ga na površino folije nanesli s petimi različnimi metodami, in sicer z metodo pršenja, valjčkanja, omakanja, impregniranja in tehnologijo superkritičnih fluidov. Učinkovitost uporabljenih snovi in metod smo preučili z analiznimi metodami: FTIR, goniometrija, pregradne lastnosti – prepustnost kisika, antioksidativnost, XPS, SEM, transparentnost, protimikrobna aktivnost ter LCA in LCC analiza. Z analiznimi metodami smo potrdili odlično antioksidativno delovanje ekstrakta brina in protimikrobno delovanje hitozana. Izkazalo se je, da je za praktično uporabo z vidika okoljske in cenovne ustreznosti najprimernejši funkcionalni plastični film, kjer smo premaz nanesli z metodo omakanja. Dosegli smo odlično protimikrobno delovanje predvsem na bakterijo Staphylococcus aureus, izvrstne pregradne in antioksidativne lastnosti, potrjene s FTIR, XPS in SEM analizo, ter zelo dobre protikondenzacijske lastnosti.
Keywords: funkcionalni plastični filmi, folija PLA, hitozan, ekstrakt brina, tehnologije nanosa, fizikalno-kemijske analize, protimikrobna aktivnost, LCA, LCC
Published in DKUM: 06.12.2023; Views: 191; Downloads: 25
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Efficient and Green Isolation of Keratin from Poultry Feathers by Subcritical Water
Mojca Škerget, Maja Čolnik, Lidija Fras Zemljič, Lidija Gradišnik, Tanja Živković Semren, Blanka Tariba Lovaković, Uroš Maver, 2023, original scientific article

Abstract: The isolation of keratin from poultry feathers using subcritical water was studied in a batch reactor at temperatures (120–250 °C) and reaction times (5–75 min). The hydrolyzed product was characterized by FTIR and elemental analysis, while the molecular weight of the isolated product was determined by SDS-PAGE electrophoresis. To determine whether disulfide bond cleavage was followed by depolymerization of protein molecules to amino acids, the concentration of 27 amino acids in the hydrolysate was analyzed by GC/MS. The optimal operating parameters for obtaining a high molecular weight protein hydrolysate from poultry feathers were 180 °C and 60 min. The molecular weight of the protein hydrolysate obtained under optimal conditions ranged from 4.5 to 12 kDa, and the content of amino acids in the dried product was low (2.53% w/w). Elemental and FTIR analyses of unprocessed feathers and dried hydrolysate obtained under optimal conditions showed no significant differences in protein content and structure. Obtained hydrolysate is a colloidal solution with a tendency for particle agglomeration. Finally, a positive influence on skin fibroblast viability was observed for the hydrolysate obtained under optimal processing conditions for concentrations below 6.25 mg/mL, which makes the product interesting for various biomedical applications.
Keywords: poultry feathers, subcritical water hydrolysis, keratin, physico-chemical characterization, cytotoxicity
Published in DKUM: 28.11.2023; Views: 193; Downloads: 9
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Kraft lignin/tannin as a potential accelerator of antioxidant and antibacterial properties in an active thermoplastic polyester-based multifunctional material
Klementina Pušnik Črešnar, Alexandra Zamboulis, Dimitrios Bikiaris, Alexandra Aulova, Lidija Fras Zemljič, 2022, original scientific article

Abstract: This research focuses on key priorities in the field of sustainable plastic composites that will lead to a reduction in CO2 pollution and support the EU’s goal of becoming carbon neutral by 2050. The main challenge is to develop high-performance polyphenol-reinforced thermoplastic composites, where the use of natural fillers replaces the usual chemical additives with non-toxic ones, not only to improve the final performance but also to increase the desired multifunctionalities (structural, antioxidant, and antibacterial). Therefore, poly (lactic acid) (PLA) composites based on Kraft lignin (KL) and tannin (TANN) were investigated. Two series of PLA composites, PLA-KL and PLA-TANN, which contained natural fillers (0.5%, 1.0%, and 2.5% (w/w)) were prepared by hot melt extrusion. The effects of KL and TANN on the PLA matrices were investigated, especially the surface physicochemical properties, mechanical properties, and antioxidant/antimicrobial activity. The surface physicochemical properties were evaluated by measuring the contact angle (CA), roughness, zeta potential, and nanoindentation. The results of the water contact angle showed that neither KL nor TANN caused a significant change in the wettability, but only a slight increase in the hydrophilicity of the PLA composites. The filler loading, the size of the particles with their available functional groups on the surfaces of the PLA composites, and the interaction between the filler and the PLA polymer depend on the roughness and zeta potential behavior of the PLA-KL and PLA-TANN composites and ultimately improve the surface mechanical properties. The antioxidant properties of the PLA-KL and PLA-TANN composites were determined using the DPPH (2,2′-diphenyl-1-picrylhydrazyl) test. The results show an efficient antioxidant behavior of all PLA-KL and PLA-TANN composites, which increases with the filler content. Finally, the KL- and PLA-based TANN have shown resistance to the Gram-negative bacteria, E. coli, but without a correlation trend between polyphenol filler content and structure.
Keywords: poly (lactic acid), Kraft lignin, tannin, multifunctionality of PLA composites, surface mechanical properties, antioxidant/antibacterial activity
Published in DKUM: 18.09.2023; Views: 303; Downloads: 9
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Pullulan-based films impregnated with silver nanoparticles from the Fusarium culmorum strain JTW1 for potential applications in the food industry and medicine
Magdalena Wypij, Mahendra Rai, Lidija Fras Zemljič, Matej Bračič, Silvo Hribernik, Patrycja Golińska, 2023, original scientific article

Abstract: Introduction: Biopolymers, such as pullulan, a natural exopolysaccharide from Aureobasidium pullulans, and their nanocomposites are commonly used in the food, pharmaceutical, and medical industries due to their unique physical and chemical properties. Methods: Pullulan was synthesized by the A. pullulans ATCC 201253 strain. Nanocomposite films based on biosynthesized pullulan were prepared and loaded with different concentrations of silver nanoparticles (AgNPs) synthesized by the Fusarium culmorum strain JTW1. AgNPs were characterized by transmission electron microscopy, Zeta potential measurements, and Fourier-transform infrared spectroscopy. In turn, the produced films were subjected to physico-chemical analyses such as goniometry, UV shielding capacity, attenuated total reflection–Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, and their mechanical and degradation properties were assessed. The antibacterial assays of the nanoparticles and the nanocomposite films against both food-borne and reference pathogens, including Listeria monocytogenes, Salmonella infantis, Salmonella enterica, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, were performed using standard methods. Results: AgNPs were small (mean 15.1 nm), spherical, and displayed good stability, being coated with protein biomolecules. When used in higher concentrations as an additive to pullulan films, they resulted in reduced hydrophilicity and light transmission for both UV-B and UV-A lights. Moreover, the produced films exhibited a smooth surface. Therefore, it can be concluded that the addition of biogenic AgNPs did not change the morphology and texture of the films compared to the control film. The nanoparticles and nanocomposite films demonstrated remarkable antibacterial activity against both food-borne and reference bacteria. The highest activity of the prepared films was observed against L. monocytogenes. Discussion: The obtained results suggest that the novel nanocomposite films prepared from biosynthesized pullulan and AgNPs can be considered for use in the development of medical products and food packaging. Moreover, this is the first report on pullulan-based nanocomposites with mycogenic AgNPs for such applications.
Keywords: Aureobasidium pullulans, pullulan, nanocomposite films, silver nanoparticles, mycosynthesis, nanobiotechnology, applied microbiology, antibacterial activity
Published in DKUM: 08.09.2023; Views: 252; Downloads: 14
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Seasonal changes in chemical profile and antioxidant activity of Padina pavonica extracts and their application in the development of bioactive chitosan/PLA bilayer film
Martina Čagalj, Lidija Fras Zemljič, Tjaša Kraševac Glaser, Eva Mežnar, Meta Sterniša, Sonja Smole Možina, María del Carmen Razola-Díaz, Vida Šimat, 2022, original scientific article

Abstract: Seaweeds are a potentially sustainable source of natural antioxidants that can be used in the food industry and possibly for the development of new sustainable packaging materials with the ability to extend the shelf-life of foods and reduce oxidation. With this in mind, the seasonal variations in the chemical composition and antioxidant activity of brown seaweed (Padina pavonica) extracts were investigated. The highest total phenolic content (TPC) and antioxidant activity (measured by ferric reducing/antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and oxygen radical absorbance capacity (ORAC)) were found for P. pavonica June extract. The TPC of 26.69 ± 1.86 mg gallic acid equivalent/g, FRAP of 352.82 ± 15.41 µmole Trolox equivalent (TE)/L, DPPH of 52.51 ± 2.81% inhibition, and ORAC of 76.45 ± 1.47 µmole TE/L were detected. Therefore, this extract was chosen for the development of bioactive PLA bilayer film, along with chitosan. Primary or quaternary chitosan was used as the first layer on polylactic acid (PLA) films. A suspension of chitosan particles with entrapped P. pavonica extract was used as the second layer. X-ray photoelectron spectroscopy confirmed the presence of layers on the material surface. The highest recorded antioxidant activity of the newly developed films was 63.82% inhibition. The developed functional films exhibited antifogging and antioxidant properties, showing the potential for application in the food industry.
Keywords: functional PLA films, seaweed and chitosan bilayer, sustainable natural antioxidants, microwave-assisted extraction
Published in DKUM: 23.08.2023; Views: 203; Downloads: 17
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Amoxicillin doped hyaluronic acid/fucoidan multifunctional coatings for medical grade stainless steel orthopedic implants
Matej Bračič, Sanja Potrč, Matjaž Finšgar, Lidija Gradišnik, Uroš Maver, Hanna Budasheva, Dorota Korte, Mladen Franko, Lidija Fras Zemljič, 2023, original scientific article

Abstract: This work investigated the potential of amoxicillin-doped hyaluronic acid/fucoidan multifunctional coatings on medical grade stainless steel as biocompatible, osteointegration enhancing, antimicrobial, and bacterial biofilm inhibiting coatings for orthopedic implants. The coatings were prepared by layer-by-layer spin coating and confirmed by optical contact angle goniometry and infrared spectroscopy. Time-of-flight secondary ion mass spectrometry showed a homogeneous distribution of the individual layers. In contrast, thermal diffusivity, and thermal conductivity measurements by photothermal beam deflection spectrometry showed diffusion of the amoxicillin into the hyaluronic acid and fucoidan layers. In vitro release of amoxicillin showed complete release within one hour, as reflected by the formation of inhibition zones against Staphylococcus aureus and Escherichia coli. Synergistic effects were observed between the hyaluronic acid and amoxicillin in inhibiting S.Aureus biofilm, and between the fucoidan and amoxicillin in improving the antioxidant properties by an ABTS radical scavenging assay. Biocompatibility was determined with human osteoblasts, confirming the potential of such multifunc- tional coatings to enhance the bioactivity of steel-based orthop edic implants.
Keywords: orthopedic implant, medical grade stainless steel, amoxicillin, hyaluronic acid, fucoidan, multifunctional coating
Published in DKUM: 18.08.2023; Views: 323; Downloads: 56
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Two-layer functional coatings of chitosan particles with embedded catechin and pomegranate extracts for potential active packaging
Sanja Potrč, Tjaša Kraševac Glaser, Alenka Vesel, Nataša Poklar Ulrih, Lidija Fras Zemljič, 2020, original scientific article

Abstract: Two-layer functional coatings for polyethylene (PE) and polypropylene (PP) films were developed for the active packaging concept. Prior to coating, the polymer films were activated by O$_2$ and NH$_3$ plasma to increase their surface free energy and to improve the binding capacity and stability of the coatings. The first layer was prepared from a macromolecular chitosan solution, while the second (upper) layer contained chitosan particles with embedded catechin or pomegranate extract. Functionalized films were analyzed physico-chemically to elemental composition using ATR-FTIR spectroscopy and XPS. Further, oxygen permeability and wettability (Contact Angle) were examined. The antimicrobial properties were analyzed by the standard ISO 22196 method, while the antioxidative properties were determined with an ABTS assay. Functionalized films show excellent antioxidative and antimicrobial efficacy. A huge decrease in oxygen permeability was achieved in addition. Moreover, a desorption experiment was also performed, confirming that the migration profile of a compound from the surfaces was in accordance with the required overall migration limit. All these properties indicate the great potential of the developed active films/foils for end-uses in food packaging.
Keywords: plazma, citozan, polifenoli, aktivno pakiranje, plasma, chitosan, polyphenols, coating, active package
Published in DKUM: 12.07.2023; Views: 368; Downloads: 22
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Razvoj in priprava biorazgradljive aktivne embalaže : magistrsko delo
Žan Jankovič, 2023, master's thesis

Abstract: V magistrskem delu smo razvili biorazgradljivo aktivno embalažo ter fizikalno-kemijsko karakterizirali in ocenili aktivni učinek (antioksidativni in protimikrobni) PLA folij. Nanosi plasti biopolimera hitozana in ekstraktov na PLA folije so bili potrjeni z metodami ATR-FTIR in XPS. Fizikalno-kemijska karakterizacija folij je potekala tudi z določevanjem omočljivosti in prepustnosti kisika. Metode so dokazale, da je z vidika omočljivosti in prepustnosti kisika zelo pomemben premaz iz ekstraktov, ki vpliva na izboljšanje omočljivosti in slabšo prepustnost kisika. Potrdili smo tudi desorpcijo hitozanov in ekstraktov iz površine folij v desorpcijsko kopel. Z analiznima spektrofotometričnima metodama DPPH in ABTS pa smo analizirali antioksidativno aktivnost folij in dokazali, da so vzorci PLA folij premazanih s hitozanoma in ekstraktoma robide ali brina izboljšale antioksidativno aktivnost. Slabše so se odrezale PLA folije premazane s hitozanoma in ekstraktom alge pri obeh metodah. Protimikrobno aktivnost smo določevali na gram pozitivno bakterijo Staphylococcus aureus in gram negativno bakterijo Escherichia coli. Vse testirane folije so imele zelo dobro protimikrobno aktivnost na bakterijo Staphylococcus aureus. Dobro protimikrobno aktivnost na bakterijo Escherichia coli pa je imel le vzorec PLA folije, ki je bil premazan s kvarternim hitozanom in premazom brina. Ker smo v PLA folijah uporabili naravne in okolju prijazne materiale za izdelavo funkcionaliziranih folij prepostavljamo, da so kompozitne folije z okoljskega vidika spremeljive, saj so biorazgradljive.
Keywords: aktivna embalaža, PLA folije, primarni hitozan, kvarterni hitozan, ekstrakti, antioksidativna embalaža, protimikrobna embalaža
Published in DKUM: 12.06.2023; Views: 420; Downloads: 58
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Analiza biorazgradljivosti sanitetnih materialov iz organskega bombaža : magistrsko delo
Viktorija Šega, 2023, master's thesis

Abstract: Magistrsko delo temelji na testiranju biorazgradljivosti sanitetnih materialov, iz organskega bombaža. S tamponi in vložki iz organskega bombaža želimo v prihodnosti zagotoviti vse manjše kopičenje sanitetnih odpadkov za enkratno uporabo na odlagališčih. Prav tako pa želimo, da se ti izdelki biorazgradijo in za okolje ne predstavljajo nevarnosti. Biorazgradljivost sanitetnih materialov iz organskega bombaža smo ovrednotili s pomočjo različnih testnih metod.
Keywords: Biorazgradljivost, organski bombaž, sanitetni materiali, razpad, okolje.
Published in DKUM: 10.05.2023; Views: 374; Downloads: 24
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