1. 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: 18
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2. Ekologija plemenitilnih procesovAlenka Ojstršek, Darinka Fakin, Selestina Gorgieva, 2024 Abstract: Skripta z naslovom »Ekologija plemenitilnih procesov« je namenjena študentom visokošolskega študijskega programa Tehnologije tekstilnega oblikovanja. Pripravljena je tako, da študente v prvih poglavjih seznani z osnovami tehnoloških procesov plemenitenja tekstilij in njihovo ekološko problematiko. Poseben problem v tekstilni industriji predstavljajo odpadne tehnološke vode, saj so močno obremenjene, vsebujejo različne kemikalije in tekstilna pomožna sredstva, različne tipe organskih barvil, imajo ekstremne pH-vrednosti in visoke vrednosti kemijske potrebe po kisiku (KPK) in biokemijske potrebe po kisiku (BPK), vsebujejo fosfate, sulfate in ostale soli, tenzide, maščobe in olja ter različne tipe težkih kovin. V nadaljevanju so v gradivu predstavljeni alternativni mediji in postopki plemenitenja, ki za dosego izbranega učinka plemenitenja porabijo manj kemikalij in tekstilnih pomožnih sredstev, manj energije in tako vplivajo na manjšo obremenitev okolja. Poseben poudarek je na alternativnih tehnikah obdelave, ki vključujejo avtomatizacijo, ki dodatno vpliva na nižjo porabo vode in energije, manjšo količino odpadkov, odpadnih vod in emisij toplogrednih plinov ter na večjo produktivnost, varnost pri delu in optimalno izrabo delovnega časa. Pridobljeno znanje bo študentom omogočilo, da bodo poleg temeljnih znanj poznali tudi napredne pristope in tehnologije pri razvoju in plemenitenju sodobnih inženirskih materialov. Keywords: ekologija, plemenitenje, tekstilni materiali, napredni postopki, odpadne vode Published in DKUM: 16.12.2024; Views: 0; Downloads: 22
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3. Production efficiency and properties of bacterial cellulose membranes in a novel grape pomace hydrolysate by Komagataeibacter melomenusus ▫$AV436^T$▫ and Komagataeibacter xylinus LMG 1518Selestina Gorgieva, Urška Jančič, Eva Cepec, Janja Trček, 2023, original scientific article Abstract: The microbial production of cellulose using different bacterial species has been extensively examined for various
industrial applications. However, the cost-effectiveness of all these biotechnological processes is strongly related to the culture medium for bacterial cellulose (BC) production. Herein, we examined a simple and modified
procedure for preparing grape pomace (GP) hydrolysate, without enzymatic treatment, as a sole growth medium
for BC production by acetic acid bacteria (AAB). The central composite design (CCD) was used to optimise the GP
hydrolysate preparation toward the highest reducing sugar contents (10.4 g/L) and minimal phenolic contents
(4.8 g/L). The experimental screening of 4 differently prepared hydrolysates and 20 AAB strains identified the
recently described species Komagataeibacter melomenusus AV436T as the most efficient BC producer (up to 1.24 g/
L dry BC membrane), followed by Komagataeibacter xylinus LMG 1518 (up to 0.98 g/L dry BC membrane). The
membranes were synthesized in only 4 days of bacteria culturing, 1 st day with shaking, followed by 3 days of
static incubation. The produced BC membranes in GP-hydrolysates showed, in comparison to the membranes
made in a complex RAE medium 34 % reduction of crystallinity index with the presence of diverse cellulose
allomorphs, presence of GP-related components within the BC network responsible for the increase of hydrophobicity, the reduction of thermal stability and 48.75 %, 13.6 % and 43 % lower tensile strength, tensile
modulus, and elongation, respectively. Here presented study is the first report on utilising a GP-hydrolysate
without enzymatic treatment as a sole culture medium for efficient BC production by AAB, with recently
described species Komagataeibacter melomenusus AV436T as the most efficient producer in this type of food-waste
material. The scale-up protocol of the scheme presented here will be needed for the cost-optimisation of BC
production at the industrial levels. Keywords: grape pomace hydrolysate, bacterial cellulose, acetic acid bacteria, Komagataeibacter melomenusus Published in DKUM: 26.07.2024; Views: 98; Downloads: 11
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4. Efficiency of neat and quaternized-cellulose nanofibril fillers in chitosan membranes for direct ethanol fuel cellsMaša Hren, Damjan Makuc, Janez Plavec, Michaela Roschger, Viktor Hacker, Boštjan Genorio, Mojca Božič, Selestina Gorgieva, 2023, original scientific article Keywords: chitosan, cellulose nanofibrils, anion exchange membrane, direct alkaline alcohol fuel cells Published in DKUM: 10.04.2024; Views: 222; Downloads: 18
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5. From nature to lab : sustainable bacterial cellulose production and modification with synthetic biologyVid Potočnik, Selestina Gorgieva, Janja Trček, 2023, review article Abstract: Bacterial cellulose (BC) is a macromolecule with versatile applications in medicine, pharmacy, biotechnology, cosmetology, food and food packaging, ecology, and electronics. Although many bacteria synthesize BC, the most efficient BC producers are certain species of the genera Komagataeibacter and Novacetimonas. These are also food-grade bacteria, simplifying their utilization at industrial facilities. The basic principles of BC synthesis are known from studies of Komagataeibacter xylinus, which became a model species for studying BC at genetic and molecular levels. Cellulose can also be of plant origin, but BC surpasses its purity. Moreover, the laboratory production of BC enables in situ modification into functionalized material with incorporated molecules during its synthesis. The possibility of growing Komagataeibacter and Novacetimonas species on various organic substrates and agricultural and food waste compounds also follows the green and sustainable economy principles. Further intervention into BC synthesis was enabled by genetic engineering tools, subsequently directing it into the field of synthetic biology. This review paper presents the development of the fascinating field of BC synthesis at the molecular level, seeking sustainable ways for its production and its applications towards genetic modifications of bacterial strains for producing novel types of living biomaterials using the flexible metabolic machinery of bacteria. Keywords: acetic acid bacteria, bacterial cellulose, sustainable production, agricultural waste, food waste, genetic engineering, synthetic biology, biomaterial, Komagataeibacter, Novacetimonas Published in DKUM: 28.03.2024; Views: 279; Downloads: 44
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6. Study on commercially available membranes for alkaline direct ethanol fuel cellsMichaela Roschger, Sigrid Wolf, Andreas Billiani, Kurt Mayer, Maša Hren, Selestina Gorgieva, Boštjan Genorio, Viktor Hacker, 2023, original scientific article Abstract: This study provides a comparison of different commercially available low-cost anion exchange membranes (AEMs), a microporous separator, a cation exchange membrane (CEM), and an anionic-treated CEM for their application in the liquid-feed alkaline direct ethanol fuel cell (ADEFC). Moreover, the effect on performance was evaluated taking two different modes of operation for the ADEFC, with AEM or CEM, into consideration. The membranes were compared with respect to their physical and chemical properties, such as thermal and chemical stability, ion-exchange capacity, ionic conductivity, and ethanol permeability. The influence of these factors on performance and resistance was determined by means of polarization curve and electrochemical impedance spectra (EIS) measurements in the ADEFC. In addition, the influence of two different commercial ionomers on the structure and transport properties of the catalyst layer and on the performance were analyzed with scanning electron microscopy, single cell tests, and EIS. The applicability barriers of the membranes were pointed out, and the ideal combinations of membrane and ionomer for the liquid-feed ADEFC achieved power densities of approximately 80 mW cm–2 at 80 °C. Keywords: bioethanol, electrodes, fluoropolymers, ionomers, membranes Published in DKUM: 26.03.2024; Views: 189; Downloads: 17
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7. Funkcionalizacija tekstilij z izoliranimi gradniki jajčnih lupin in izdelava nanovlaken iz le - teh : magistrsko deloRosvita Pliberšek, 2024, master's thesis Abstract: Glavna tema magistrske naloge je izolacija gradnikov jajčnih lupin kokoši in prepelice ter obdelava sintetičnih (poliester, PES) ter naravnih (bombaž) tekstilij z le-tem. Izbira teme je temeljila na pogledu na jajčne lupine kot odpadek in hkrati kot uporabno surovino, ki lahko izboljša lastnosti drugih surovin oz. materialov, pri tem pa lahko ustvarimo napredek na področju ognjevarnih, medicinskih ter UV-zaščitnih oblačil.
V nalogi smo preverjali izbrane funkcionalne lastnosti vodne raztopine jajčnih lupin, kot so: velikosti delcev in zeta potencial, pH vrednost, motnost, površinska napetost, stični kot, električna prevodnost in antioksidativnost; ter analizirali učinkovitost obdelave poliestrnih (PES) in bombažnih tkanin s pridobljenimi raztopinami, pri čemer smo uporabili napredne preparativne (hidrotermična razgradnja- hidroliza) in analitske metode (merjenje pH, spektroskopija).
Ugotovili smo, da je vzorec v obliki vodne raztopine pokazal dobre lastnosti na področju površinske lastnosti, prav tako je pokazalo dobre rezultate pri meritvah zeta potenciala ter pri merjenju električne prevodnosti. Pri obdelanih PES in bombažnih vzorcih s to raztopino jajčnih lupin, pa lahko poudarim, da so bili vidni rezultati na področju ognjevarnosti, protimikrobnosti in UZF. Rezultati sicer niso bili izraziti, ampak bili opazni in so mejili v dobro smer. Keywords: jajčne lupine, hidroliza, funkcionalizacija, izolirani gradniki, PES in bombažne tekstilije, ognjevarnost, medicinske tekstilije, UV zaščita Published in DKUM: 22.03.2024; Views: 334; Downloads: 28
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8. Dopamine-assisted modification of polypropylene film to attain hydrophilic mineral-rich surfacesAlenka Ojstršek, Angela Chemelli, Azra Osmić, Selestina Gorgieva, 2023, original scientific article Abstract: The presented study focuses on the modification of polypropylene (PP) film with tetraethyl orthosilicate (TEOS) under heterogeneous conditions via polydopamine/polyethylene imine (PDA/PEI) chemistry using a facile dip-coating procedure to attain hydrophilic mineral-rich surfaces. Thus, the resulting PP-based films were further immersed in ion-rich simulated body fluid (SBF) to deposit Ca-based minerals onto the film’s surfaces efficiently. In addition, the chemical reaction mechanism on PP film was proposed, and mineralisation potential inspected by determination of functional groups of deposits, zeta potential, hydrophilicity and surface morphology/topography using Fourier transform infrared (FTIR) spectroscopy, streaming potential, water contact angle (WCA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained results show the improved wettability of samples on account of PDA inclusion (WCA was reduced from 103° for pure PP film to 28° for PDA-modified film), as well as the presence of functional groups, due to the PDA/PEI/TEOS surface functionalisation, increased the ability of minerals to nucleate on the PP film’s surface when it was exposed to an SBF medium. Moreover, the higher surface roughness due to the silica coatings influenced the enhanced anchoring and attachment of calcium phosphate (CaP), revealing the potential of such a facile approach to modify the chemically inert PP films, being of particular interest in different fields, including regenerative medicine. Keywords: polypropylene film, dopamine-assisted modification, hydrophilicity, mineralization Published in DKUM: 15.03.2024; Views: 300; Downloads: 5
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9. GO-enabled bacterial cellulose membranes by multistep, in situ loading : effect of bacterial strain and loading pattern on nanocomposite propertiesTobiasz Gabryś, Beata Fryczkowska, Urška Jančič, Janja Trček, Selestina Gorgieva, 2023, original scientific article Abstract: This paper presents the results of research on the preparation and properties of GO/BC nanocomposite from bacterial cellulose (BC) modified with graphene oxide (GO) using the in situ method. Two bacterial strains were used for the biosynthesis of the BC: Komagataeibacter intermedius LMG 18909 and Komagataeibacter sucrofermentans LMG 18788. A simple biosynthesis method was developed, where GO water dispersion was added to reinforced acetic acid-ethanol (RAE) medium at concentrations of 10 ppm, 25 ppm, and 50 ppm at 24 h and 48 h intervals. As a result, a GO/BC nanocomposite membrane was obtained, characterized by tensile strength greater by 150% as compared with the pure BC (̴ 50 MPa) and lower volume resistivity of ~4 ∙ 109 Ω × cm. Moreover, GO addition increases membrane thickness up to ~10% and affects higher mass production, especially with low GO concentration. All of this may indicate the possibility of using GO/BC membranes in fuel cell applications. Keywords: bacterial cellulose, graphene oxide, nanocomposite, structural analysis Published in DKUM: 13.03.2024; Views: 341; Downloads: 13
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10. Cellulose nanofibrils-reinforced pectin membranes for the adsorption of cationic dyes from a model solutionAlenka Ojstršek, Selestina Gorgieva, 2024, original scientific article Abstract: In the presented research, a facile, one-step method for the fabrication of cellulose nanofibrils/pectin (CNFs/PC) membranes is described, which were tested further for their ability to remove cationic dyes from the prepared model solutions. For this purpose, ten membranes were prepared with different quantities of CNFs and PC with/without citric acid (CA) or CaCl2 as mediated crosslinking agents, and they were characterised comprehensively in terms of their physical, chemical, and hydrophilic properties. All the prepared CNFs/PC membranes were hydrophilic with a Water Contact Angle (WCA) from 51.23◦ (without crosslinker) up to 78.30◦ (CaCl2 ) and swelling of up to 485% (without crosslinker), up to 437% (CaCl2 ) and up to 270% (CA). The stability of membranes was decreased with the increase in PC; thus, only four membranes (M1, M2, M3 and M5) were stable enough in water after 24 h, and these were additionally applied in the adsorption trials, using two structurally different cationic dyes, i.e., C.I. Basic Yellow 28 (BY28) and C.I. Basic Blue 22 (BB22), in four concentrations. The highest total surface charge of M3 (2.83 mmol/g) as compared to the other membranes influenced the maximal removal efficiency of both dyes, up to 37% (BY28) and up to 71% (BB22), depending on the initial dye concentration. The final characteristics of the membranes and, consequently, the dye’s absorption ability could be tuned easily by changing the ratio between the CNFs and PC, as well as the type and amount of crosslinker. Keywords: cellulose nanofibrils, pectin, cationic dyes, adsorption, dye removal Published in DKUM: 12.03.2024; Views: 320; Downloads: 18
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