1. High oxygen barrier chitosan films neutralized by alkaline nanoparticlesUrška Jančič, Mojca Božič, Silvo Hribernik, Tamilselvan Mohan, Rupert Kargl, Karin Stana-Kleinschek, Selestina Gorgieva, 2021, original scientific article Abstract: The most frequent neutralisation procedure, applied on chitosan (CS) films includes treatment with NaOH base. Such treatment endows CS films with stability in water, yet, same can significantly decrease the film performance. In the present paper, we investigate Mg(OH)2 nanoparticles as a neutralisation agent for CS solutions followed by casting into films. This is combined and compared with classical casting and film drying from nonneutralized solutions followed by NaOH treatment after film formation. The influence on the properties of resulting films is investigated in detail and large differences are found for structure and barrier properties. The stable, opaque-to-transparent CS films (depending on Mg(OH)2 content and post-treatment) were obtained by facile casting method of neat CS or CS–Mg(OH)2 dispersions, in the complete absence of cross-linkers and plasticizers. FTIR data demonstrate
the Mg(OH)2 and NaOH deprotonation effect, and strongly suggest intensive H-bonding interaction between CS and Mg(OH)2. X-ray photoelectron spectroscopy showed differences in the hydroxide content and protonation of CS nitrogen. The reduction of surface roughness and increase of homogeneity, the tensile strength and elongation, as well as thermal stability and excellent oxygen barrier properties were measured for CS enclosing the Mg(OH)2 nanoparticles. Further treatment with 1 M NaOH causes repacking of CS polymer chains, improving the crystallinity and water vapour barrier properties, degrading the mechanical properties by increasing the films brittleness and increasing the char formation due to reduced thermal stability.
Keywords: CS films, Mg(OH)2, neutralization, oxygen barrier properties
Published in DKUM: 14.10.2025; Views: 0; Downloads: 0
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2. Razvoj protimikrobnih lastnosti bakterijske nanoceluloze z uporabo bio-osnovanih komponentKatja Ravnjak, 2025, master's thesis Abstract: Trajnostnost je trenutno eden izmed najpomembnejših konceptov, kamor sodi načelo zaščite pred izčrpavanjem naravnih virov ter koncept zelene kemije. Z željo po implementaciji le-tega se razvijajo nove tehnologije pridobivanja naravnih materialov, uporaba le-teh ter vpeljava ponovne uporabe odpadnih materialov. Bakterijska nanoceluloza (BC) zaradi skladnosti s tem konceptom ter njenih ugodnih lastnostih pridobiva vse več pozornosti za uporabo. Kljub ugodnim lastnostim pa se pojavlja pomanjkljivost na področju uporabe medicinskih aplikacij ter drugih tehnoloških področij, kjer je zahtevano protimikrobno delovanje, ki ga BC sama po sebi ne izkazuje. V raziskovalnem delu smo se tako osredotočili na modifikacijo BC s protimikrobnimi sredstvi. V ta namen smo si izbrali uporabo kvaternega hitozana (HTCC) ter odpad papirne industrije, ki vsebuje lignosulfonat (O-LS), kar je v skladu s konceptom trajnostnosti. Uporabljen HTCC je bil komercialno pridobljen kemijsko očiščen proizvod, medtem ko smo O-LS uporabili v obliki odpada papirne industrije podjetja Mondi, zaradi česar predvidevamo, da so poleg le-tega v sledovih prisotne še druge kemijske spojine. BC membrane, ki smo jih uporabili za modifikacijo so bile komercialno pridobljene, ki smo jih nadalje pripravili v dveh različnih oblikah – kot membrane in kot niti. Modifikacijo smo potrdili s sledečimi metodami: atenuirana popolna refleksija infrardeče spektroskopije s Fourierevo transformacijo (ATR-FTIR), rentgenska praškovna difrakcija (XRD), potenciometrična titracija, goniometrija, optična mikroskopija, vrstična elektronska mikroskopija (SEM), navzemanje vode (WU),
mehanska testiranja, protimikrobna testiranja. S pomočjo poglobljene analize smo potrdili spremembe v lastnostih BC v odvisnosti od strukture (membrana vs. nit) ter protimikrobno delovanje BC membran za S. aureus in S. epidermidis pri BC membrani modificirani z O-LS ter protimikrobno delovanje za S. aureus pri BC membrani modificirani s HTCC. Protimikrobno delovanje pri BC modificirani s HTCC je zagotovila kvaterna dušikova skupina v molekuli HTCC, pri BC modificirani z O-LS pa prisotnost fenolne spojine (prisotnost obeh smo potrdili z ATR-FTIR analizo). Z modifikacijo smo pridobili ultra čist, trajnostni material s protimikrobnim delovanjem, ki ima potencialno uporabno vrednost v medicini, kot tudi na drugih področjih kjer je tovrstna aktivnost zaželena.
Keywords: bakterijska nanoceluloza, hitozan, lignosulfonat, protimikrobne lastnosti
Published in DKUM: 08.09.2025; Views: 0; Downloads: 0
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3. Bralni kotiček na prostem kot rezultat projektnega dela v osnovni šoli : magistrsko deloMarko Bračič, 2025, master's thesis Abstract: Projektno učno delo je sodoben pedagoški pristop, ki učencem omogoča aktivno vlogo pri reševanju izzivov iz vsakdanjega življenja. Pri tem razvijajo ključne kompetence, kot so ustvarjalnost, samostojnost, sodelovanje in odgovornost. Zunanji prostori šole ponujajo številne možnosti za učenje, vendar pogosto ostajajo neizkoriščeni.
Devetošolci so v okviru interesne dejavnosti, ki je potekala po načelih projektnega dela, oblikovali in izvedli projekt bralnega kotička v šolskem parku. Z mislijo na mlajše učence so izdelali ergonomsko oblikovano klop, knjigobežnico in lesen podest s cvetlično gredo ter uredili okolico. Ob tem so pridobivali tehnično znanje, spoznavali materiale, orodja in delovne postopke ter krepili občutek pripadnosti šolskemu prostoru. Čeprav je končni izdelek uspešno narejen, največjo vrednost predstavlja proces, ki je učencem omogočil izkustveno učenje, sodelovanje in aktivno sooblikovanje šolskega okolja.
Keywords: projektno učno delo, tehnika in tehnologija, knjigobežnica, bralni kotiček, osnovna šola
Published in DKUM: 16.07.2025; Views: 0; Downloads: 10
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4. Fizikalno-Kemijska in morfološka primerjava celuloze iz različnih virov : diplomsko deloMichela Sossi, 2025, undergraduate thesis Abstract: V diplomskem delu je bila narejena primerjava med celuloznimi materiali iz treh različnih virov, t. j. bombaža, lesa in bakterij glede na fizikalno-kemijske in morfološke lastnosti. Cilj raziskave je bil ugotoviti, kako izvor in način priprave materiala na osnovi celuloze vplivata na določene lastnosti, zlasti na sposobnost absorpcije barvil. Zastavljena hipoteza je predvidevala značilne razlike med vzorci glede na vir in pripravo. Za karakterizacijo materiala je bilo uporabljenih več metod, t.j. FTIR, SEM, optična mikroskopija, UV-VIS, gravimetrija, in goniometrija. Na podlagi rezultatov je bilo ugotovljeno, da vir in način priprave celuloze izrazito vpliva na morfološko strukturo, hidrofilnost in zmožnost adsorpcije barvila, pri čem je bilo potrjeno, da material iz bombažne celuloze je najbolj učinkovit in ima najvišjo kapaciteto adsorpcije barvila.
Keywords: bakterijska nanoceluloza, bombaž, karakterizacija, lastnosti, morfologija
Published in DKUM: 08.07.2025; Views: 0; Downloads: 16
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5. Metallisation of textiles and protection of conductive layers: An overview of application techniquesAlenka Ojstršek, Olivija Plohl, Selestina Gorgieva, Manja Kurečič, Urška Jančič, Silvo Hribernik, Darinka Fakin, 2021, review article Abstract: The rapid growth in wearable technology has recently stimulated the development of
conductive textiles for broad application purposes, i.e., wearable electronics, heat generators, sensors,
electromagnetic interference (EMI) shielding, optoelectronic and photonics. Textile material, which
was always considered just as the interface between the wearer and the environment, now plays
a more active role in different sectors, such as sport, healthcare, security, entertainment, military,
and technical sectors, etc. This expansion in applied development of e-textiles is governed by a
vast amount of research work conducted by increasingly interdisciplinary teams and presented
systematic review highlights and assesses, in a comprehensive manner, recent research in the field of
conductive textiles and their potential application for wearable electronics (so called e-textiles), as
well as development of advanced application techniques to obtain conductivity, with emphasis on
metal-containing coatings. Furthermore, an overview of protective compounds was provided, which
are suitable for the protection of metallized textile surfaces against corrosion, mechanical forces,
abrasion, and other external factors, influencing negatively on the adhesion and durability of the
conductive layers during textiles’ lifetime (wear and care). The challenges, drawbacks and further
opportunities in these fields are also discussed critically.
Keywords: metallization, conductive textiles, e-textiles, coatings techniques, protective coatings, durability
Published in DKUM: 16.06.2025; Views: 0; Downloads: 1
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6. Bioactive bacterial nanocellulose membranes for non-surgical debridement and infection prevention in burn wound healingUrška Jančič, Isabella Nacu, Liliana Vereştiuc, Fiorenza Rancan, Selestina Gorgieva, 2025, original scientific article Abstract: Novel bioactive bacterial nanocellulose (BnC) membranes were developed for effective, non-surgical debridement and infection-prevention in burn wound healing. Membranes were modified in situ with carboxymethyl cellulose (CMC) and ex situ with the proteolytic enzyme bromelain (Br) and antimicrobial peptide nisin (N). Post-processing into stable cellulose nanocrystal dispersions (ζ = -26 mV), enables assembly of model films for demonstration of high, irreversible bromelain (95 %) and nisin (99.5 %) adsorption. The BnC-CMC and BnC-CMC-N membranes were in vitro cytocompatible for HaCaT cells and induced faster cell proliferation with cell viability exceeding 100 % after 24 h incubation. The innovative aspect of this study lies in the ex vivo evaluation using an advanced human skin explant model with induced burns, providing a realistic, physiologically relevant assessment of membrane performance. Ex vivo experiments indicated the cytocompatibility of the BnC-CMC membrane with no acute toxicity or skin irritation, while nisin presence resulted in moderate irritating effect. Notably, the BnC-CMC-Br membrane showed digestion of intercellular junctions in the epidermis, while not inducing acute toxicity and skin irritation. By leveraging this innovative ex vivo human skin model in novel BnC-based membranes testing, the study provides a crucial translational step, bridging in vitro assessments and clinical applications for burn wound treatment.
Keywords: bacterial nanocellulose, Bromelain, Nisin, Carboxymethyl cellulose, antimicrobial function, bioactive, burn wound treatment
Published in DKUM: 01.04.2025; Views: 0; Downloads: 10
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7. Bromelain and nisin: The natural antimicrobials with high potential in biomedicineUrška Jančič, Selestina Gorgieva, 2022, review article Abstract: Infectious diseases along with various cancer types are among the most significant public
health problems and the leading cause of death worldwide. The situation has become even more
complex with the rapid development of multidrug-resistant microorganisms. New drugs are urgently
needed to curb the increasing spread of diseases in humans and livestock. Promising candidates
are natural antimicrobial peptides produced by bacteria, and therapeutic enzymes, extracted from
medicinal plants. This review highlights the structure and properties of plant origin bromelain and
antimicrobial peptide nisin, along with their mechanism of action, the immobilization strategies, and
recent applications in the field of biomedicine. Future perspectives towards the commercialization of
new biomedical products, including these important bioactive compounds, have been highlighted.
Keywords: bromelain, nisin, bioactivity, antimicrobial agent, biomedicine, carrier
Published in DKUM: 27.03.2025; Views: 0; Downloads: 5
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8. Decontamination efficiency of thermal, photothermal, microwave, and steam treatments for biocontaminated household textilesBranko Neral, Selestina Gorgieva, Manja Kurečič, 2022, original scientific article Abstract: With the outbreak of the COVID-19 pandemic, textile laundering hygiene has proved to be
a fundamental measure in preventing the spread of infections. The first part of our study evaluated
the decontamination efficiency of various treatments (thermal, photothermal, and microwave) for
bio contaminated textiles. The effects on textile decontamination of adding saturated steam into
the drum of a household textile laundering machine were investigated and evaluated in the second
part of our study. The results show that the thermal treatment, conducted in a convection heating
chamber, provided a slight reduction in efficiency and did not ensure the complete inactivation of
Staphylococcus aureus on cotton swatches. The photothermal treatment showed higher reduction
efficiency on contaminated textile samples, while the microwave treatment (at 460 W for a period of
60 s) of bio contaminated cotton swatches containing higher moisture content provided satisfactory
bacterial reduction efficiency (more than 7 log steps). Additionally, the treatment of textiles in the
household washing machine with the injection of saturated steam into the washing drum and a mild
agitation rhythm provided at least a 7 log step reduction in S. aureus. The photothermal treatment
of bio contaminated cotton textiles showed promising reduction efficiency, while the microwave
treatment and the treatment with saturated steam proved to be the most effective.
Keywords: household textiles, thermal treatment, decontamination, reduction efficiency
Published in DKUM: 24.03.2025; Views: 0; Downloads: 1
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9. Nisin-loaded gelatin microparticles for the enhanced bioactivity of bacterial nanocelluloseMaša Hren, Janja Trček, Aleksandra Šakanović, Hristina Obradović, Mateja Erdani-Kreft, Silvo Hribernik, Selestina Gorgieva, 2025, original scientific article Abstract: Bacterial nanocellulose (BnC) is of immense importance in medicine, although its lack of bioactivity present intriguing issue. We propose a method to modify BnC with gelatin and nisin biomolecules, and explore their synergistic effect on the antimicrobial activity. Gelatin microparticles (without/with nisin loading) with a size ~0.5 μm and ~ 1.3 μm were prepared by spray drying and stabilised by dehydrothermal treatment. Modified BnC-based membranes supported the formation of biologically relevant minerals and were non-cytotoxic to human gingival fibroblast cells (HGF). The presence of gelatin microparticles improved the viability of HGF by approximately 20 %, due to the effect of gelatin alone, independent of the addition of nisin. BnC coated with a nisin/gelatin solution reduces the viability of HGF by about 20 %, but this negative effect is not observed by nisin coated gelatin microparticles. The cell viability of BnC membranes was above 90 % in both porcine and human urothelial cells. The antimicrobial activity study confirmed an inhibitory effect of membranes modified with nisin-coated microparticles or a gelatin/nisin solution against Staphylococcus aureus at a non-cytotoxic nisin dose (150 μg/mL). The study demonstrates the structural effects of gelatin and gelatin/nisin mixtures on the bioactivity of BnC and provides a rationale for the modification procedure.
Keywords: bacterial nanocellulose, gelatin, nisin, spray-drying, antimicrobial function, bioactivity
Published in DKUM: 10.03.2025; Views: 0; Downloads: 10
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10. Razvoj bioaktivnih membran na osnovi bakterijske nanoceluloze za uporabo pri opeklinah : doktorska disertacijaUrška Jančič, 2024, doctoral dissertation Abstract: V doktorski disertaciji smo se osredotočili na razvoj novih bioaktivnih membran na osnovi bakterijske nanoceluloze (BnC), in situ, modificirane s karboksimetil celulozo (CMC), in ex situ, modificirane s proteolitskim encimom bromelainom (Br) in/ali protimikrobnim peptidom nizinom (N) za nekirurško odstranitev mrtvega kožnega tkiva (mrtvine) pri opeklinah ter hitrejše, učinkovitejše in netoksično celjenje opeklin. Membrane BnC smo producirali s pred kratkim opisano novo vrsto ocetnokislinske bakterije Komagataeibacter melomenusus AV436T, saj je bila ta izmed testiranih ocetnokislinskih bakterij najproduktivnejša. Za učinkovito odstranitev ostankov bakterij in komponent gojišča smo optimizirali alkalno obdelavo membran (1 h 0,5 M NaOH), s CMC-Br konjugati pa smo določili optimalno masno razmerje zamreževalca EDC/NHS (2/1) za najvišjo ohranitev specifične proteolitske aktivnosti bromelaina. In situ modifikacijo membran BnC smo izvedli z dodajanjem CMC v gojišče RAE za namnoževanje bakterij, kar je vodilo v nastanek membran BnC-CMC s karboksilnimi skupinami, gostejšo razporeditvijo fibrilov in izboljšanim rehidracijskim razmerjem v primerjavi z membrano BnC. Bromelain smo ex situ imobilizirali na (modificirane) membrane BnC z adsorpcijo in kovalentno vezavo z uporabo zamreževalca EDC/NHS, pri čemer smo za identifikacijo optimalne kombinacije procesnih parametrov (koncentracije CMC, bromelaina in zamreževalca EDC/NHS) z maksimalno specifično proteolitsko aktivnostjo bromelaina uporabili metodologijo odzivnih površin (RSM). S koimobilizacijo bromelaina in nizina smo proučevali sinergistični učinek obeh komponent s ciljem razširitve protimikrobnega delovanja in pridobitve proteolitskega delovanja. Optimalne bioaktivne membrane in njihove reference smo okarakterizirali s fizikalno-kemijskimi analiznimi metodami, kar je vključevalo ATR-FTIR in mikroanalizo FTIR, SEM, EDS, XPS, XRD, stične kote, kapaciteto zadrževanja vode, rehidracijsko razmerje, vsebnost vode, zeta potencial, TGA, mehanske lastnosti in specifično proteolitsko aktivnost. Biološko aktivnost membran smo analizirali s testiranjem protimikrobne aktivnosti in z različnimi in vitro (celična viabilnost in morfologija celic NHDF in HaCaT, celjenje ran) in ex vivo metodami (testiranje bioadhezije na modelu piščančje kože, testiranja toksičnosti na ekspantatih človeške kože – histološke študije, aktivnost LDH, sproščanje IL-8). Optimalni imobilizacijski pogoji (9 mg/mL CMC in 10 mg/mL bromelaina) so omogočili hiperaktivacijo encima s specifično proteolitsko aktivnostjo 2,3 U/mg in 39,1 % učinkovitostjo imobilizacije. Imobilizacija bromelaina in/ali nizina na membrano BnC-CMC je povečala povprečen premer nanovlaken, rehidracijsko razmerje in vsebnost vode ter izboljšala protimikrobno delovanje in adhezijske lastnosti. Membrani BnC-CMC in BnC-CMC-N sta bili in vitro citokompatibilni za celice NHDF in HaCaT ter sta povzročili hitrejšo proliferacijo celic HaCaT in/ali migracijo celic NHDF kot komercialni produkt Vivamel. Ex vivo analiza na ekspantatih človeške kože je za membrano BnC-CMC pokazala citokompatibilnost brez akutne toksičnosti in iritacije kože, membrana BnC-CMC-N je bila prav tako citokompatibilna brez akutne toksičnosti, vendar z zmernim dražilnim učinkom. Membrana BnC-CMC-Br je na ekspantatih človeške kože izkazovala aktivnost, ki se je odražala v razgradnji medceličnih stikov v epidermisu, vendar ni povzročila inducirajoče akutne toksičnosti in iritacije kože. Pripravljene membrane BnC-CMC, BnC-CMC-Br in BnC-CMC-N izkazujejo potencial za uporabo v različnih fazah zdravljenja opeklin.
Keywords: bakterijska nanoceluloza, bioaktivnost, bromelain, nizin, protimikrobna aktivnost, proteolitska aktivnost, membrana, opekline
Published in DKUM: 14.01.2025; Views: 0; Downloads: 119
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