1. Antithrombogenic polysaccharide coatings to improve hemocompatibility, protein-repellence, and endothelial cell responseMatej Bračič, Bence M. Nagy, Olivija Plohl, Florian Lackner, Tobias Alexander Steindorfer, Roland Fischer, Thomas Heinze, Andrea Olschewski, Karin Stana-Kleinschek, Chandran Nagaraj, Tamilselvan Mohan, 2024, izvirni znanstveni članek Opis: Polyester biomaterials play a crucial in vascular surgery, but suffer from unspecific protein adsorption,
thrombogenicity, and inadequate endothelial cell response, which limit their success. To address these issues, we investigated the functionalization of polyester biomaterials with antithrombogenic polysaccharide coatings. A two-step and water-based method was used to coat cationized polycaprolactone with
different sulfated polysaccharides (SPS), which resulted in long-term stability, tunable morphology,
roughness, film thickness, chemical compositions, zeta potential, and water content. The coatings significantly increased the anticoagulant activity and reduced the thrombogenicity of polycaprolactone, particularly with highly sulfated heparin and cellulose sulfate. Less SPS, such as chondroitin sulfate, fucoidan,
and carrageenan, despite showing reduced anticoagulant activity, also exhibited lower fibrinogen adsorption. The adhesion and viability of human primary endothelial cells cultured on modified polycaprolactone
correlated with the type and sulfate content of the coatings.
Ključne besede: polyester biomaterials, vascular surgery, antithrombogenic polysaccharide coatings
Objavljeno v DKUM: 10.09.2024; Ogledov: 65; Prenosov: 10
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2. Decomposition and fragmentation of conventional and biobased plastic wastes in simulated and real aquatic systemsOlivija Plohl, Lidija Fras Zemljič, Alen Erjavec, Noemi Sep, Maja Čolnik, Yee Van Fan, Mojca Škerget, Annamaria Vujanović, Lidija Čuček, Julija Volmajer Valh, 2024, izvirni znanstveni članek Opis: Plastics play a crucial role in our daily lives. The challenge, however, is that they become waste and contribute to a global environmental problem, increasing concerns about pollution and the urgent need to protect the environment. The accumulation and fragmentation of plastic waste, especially micro- and nanoplastics in aquatic systems, poses a significant threat to ecosystems and human health. In this study, the decomposition and fragmentation processes of conventional and biobased plastic waste in simulated water bodies (waters with different pH values) and in real water systems (tap water and seawater) are investigated over a period of one and six months. Three types of plastic were examined: thermoplastic polyethylene terephthalate and thermoset melamine etherified resin in the form of nonwovens and biobased polylactic acid (PLA) in the form of foils. Such a comprehensive study involving these three types of plastics and the methodology for tracking degradation in water bodies has not been conducted before, which underlines the novelty of the present work. After aging of the plastics, both the solid fraction and the leachate in the liquid phase were carefully examined. The parameters studied include mass loss, structural changes and alterations in functional groups observed in the aged plastics. Post-exposure assessment of the fragmented pieces includes quantification of the microplastic, microscopic observations and confirmation of composition by in situ Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. The leachate analysis includes pH, conductivity, turbidity, total carbon and microplastic size distribution. The results highlight the importance of plastic waste morphology and the minor degradation of biobased PLA and show that microfibers contribute to increased fragmentation in all aquatic systems and leave a significant ecological footprint. This study underlines the crucial importance of post-consumer plastic waste management and provides valuable insights into strategies for environmental protection. It also addresses the pressing issue of plastic pollution and provides evidence-based measures to mitigate its environmental impact.
Ključne besede: polylactic acid, polyethylene terephthalate fabric, melamine etherifed resin fabric, aquatic environment, fragmentation, waste disposal
Objavljeno v DKUM: 09.09.2024; Ogledov: 73; Prenosov: 20
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3. Novel magnetic iron oxide-dextran sulphate nanocomposites as potential anticoagulants: Investigating interactions with blood components and assessing cytotoxicityOlivija Plohl, Lidija Fras Zemljič, Boštjan Vihar, Alenka Vesel, Sašo Gyergyek, Uroš Maver, Irena Ban, Matej Bračič, 2024, izvirni znanstveni članek Opis: Examining the critical role of anticoagulants in medical practice, particularly their central function in preventing abnormal blood clotting, is of the utmost importance. However, the study of interactions between blood proteins and alternative anticoagulant nano-surfaces is still understood poorly. In this study, novel approach involving direct functionalisation of magnetic iron oxide nanoparticles (MNPs) as carriers with sulphated dextran (s-dext) is presented, with the aim of evaluating the potential of magnetically-responsive MNPs@s-dext as anticoagulants. The physicochemical characterisation of the synthesised MNPs@s-dext includes crystal structure analysis, morphology study, surface and electrokinetic properties, thermogravimetric analysis and magnetic properties` evaluation, which confirms the successful preparation of the nanocomposite with sulfonate groups. The anticoagulant potential of MNPs@s-dext was investigated using a standardised activated partial thromboplastin time (APTT) test and a modified APTT test with a quartz crystal microbalance with dissipation (QCM-D) which confirmed the anticoagulant effect. Time-resolved solid-liquid interactions between the MNPs@s-dext and model blood proteins bovine serum albumin and fibrinogen were also investigated, to gain insight into their hemocompatibility, and revealed protein-repellence of MNPs@s-dext against blood proteins. The study also addressed comprehensive cytotoxicity studies of prepared nanocomposites, and provided valuable insights into potential applicability of MNPs@s-dext as a promising magnetic anticoagulant in biomedical contexts.
Ključne besede: dextran sulphate, magnetic nanoparticles, blood protein interactions, clot formation, anticoagulants, cytotoxicity studies
Objavljeno v DKUM: 25.07.2024; Ogledov: 107; Prenosov: 20
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4. Exploring chitosan-plant extract bilayer coatings: Advancements in active food packaging via polypropylene modificationSaša 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
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5. Bioactive functional nanolayers of chitosan-lysine surfactant with single- and mixed-protein-repellent and antibiofilm properties for medical implantsUrban 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
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6. Using different surface energy models to assess the interactions between antiviral coating films and phi6 model virusZdenka Peršin Fratnik, Olivija Plohl, Vanja Kokol, Lidija Fras Zemljič, 2023, izvirni znanstveni članek Opis: High molecular weight chitosan (HMWCh), quaternised cellulose nanofibrils (qCNF), and their mixture showed antiviral potential in liquid phase, while this effect decreased when applied to facial masks, as studied in our recent work. To gain more insight into material antiviral activity, spin-coated thin films were prepared from each suspension (HMWCh, qCNF) and their mixture with a 1:1 ratio. To understand their mechanism of action, the interactions between these model films with various polar and nonpolar liquids and bacteriophage phi6 (in liquid phase) as a viral surrogate were studied. Surface free energy (SFE) estimates were used as a tool to evaluate the potential adhesion of different polar liquid phases to these films by contact angle measurements (CA) using the sessile drop method. The Fowkes, Owens–Wendt–Rabel–Kealble (OWRK), Wu, and van Oss–Chaudhury–Good (vOGC) mathematical models were used to estimate surface free energy and its polar and dispersive contributions, as well as the Lewis acid and Lewis base contributions. In addition, the surface tension SFT of liquids was also determined. The adhesion and cohesion forces in wetting processes were also observed. The estimated SFE of spin-coated films varied between mathematical models (26–31 mJ/m2) depending on the polarity of the solvents tested, but the correlation between models clearly indicated a significant dominance of the dispersion components that hinder wettability. The poor wettability was also supported by the fact that the cohesive forces in the liquid phase were stronger than the adhesion to the contact surface. In addition, the dispersive (hydrophobic) component dominated in the phi6 dispersion, and since this was also the case in the spin-coated films, it can be assumed that weak physical van der Waals forces (dispersion forces) and hydrophobic interactions occurred between phi6 and the polysaccharide films, resulting in the virus not being in sufficient contact with the tested material during antiviral testing of the material to be inactivated by the active coatings of the polysaccharides used. Regarding the contact killing mechanism, this is a disadvantage that can be overcome by changing the previous material surface (activation). In this way, HMWCh, qCNF, and their mixture can attach to the material surface with better adhesion, thickness, and different shape and orientation, resulting in a more dominant polar fraction of SFE and thus enabling the interactions within the polar part of phi6 dispersion.
Ključne besede: films, surface free energy, SFE mathematical models, phi6, wettability, spreading, interactions
Objavljeno v DKUM: 21.04.2023; Ogledov: 555; Prenosov: 38
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7. Fragmentacija plastičnih materialov v različnih vodnih okoljih : magistrsko deloNoemi Sep, 2023, magistrsko delo Opis: Namen magistrske naloge je bil preučiti in primerjati mehanizme degradacije oziroma fragmentacije štirih konvencionalnih plastičnih materialov (polietilen tereftalat (PET), recikliran polietilen tereftalat (rPET), vlakna polietilen tereftaltata (PETFIB), vlakna melaminske eterificirane smole (MERFIB)) in enega biorazgradljivega plastičnega materiala (polilaktična kislina (PLA)) v treh modelnih vodah z različnimi vrednostmi pH (4, 7 in 10) ter v dveh realnih vodah (pitna voda in morska voda). Fragmentacijo plastičnih materialov smo preučevali za njihovo izpostavljenost v treh različnih časovnih obdobjih (1 mesec, 3 meseci in 6 mesecev). Tako smo primerjali kinetiko degradacije/fragmentacije različnih plastičnih materialov ter preučevali vpliv različnih parametrov, kot sta časovna izpostavljenost, vpliv naravnega okolja ter pH vrednosti na kinetiko degradacije. V sklopu magistrske naloge smo prav tako izvedli eksperiment, pri čemer smo uporabili 10-kratno količino začetnega vzorca, kjer smo spremenili razmerje med materialom in vodnim medijem. Na koncu smo izvedli še standardni test za določanje toksičnost (TCLP) po standardu SW-846 Test Method 1311.
Spremembe v masi plastičnih materialov ter količino nastale mikroplastike smo kvantificirali s pomočjo gravimetrije. Morebitne morfološke spremembe materiala smo okarakterizirali s pomočjo optičnega mikroskopa, morebitne spremembe funkcionalnih skupin pa smo spremljali z ATR-FTIR spektroskopijo. V vodnih medijih smo spremljali spreminjanje naslednjih parametrov: pH vrednost, prevodnost, motnost, povprečno velikost delcev ter skupni organski ogljik.
Med petimi preučevanimi materiali kaže MERFIB največjo stopnjo degradacije, najbolj obstojen med preučevanimi materiali pa je konvencionalni material PET. Po šestih mesecih izpostavljenosti smo pri materialih PET, rPET in MERFIB lahko zasledili največjo stopnjo degradacije v primeru uporabe modelne vode s pH vrednostjo 4. V primeru materiala PETFIB pa se je za najučinkovitejše degradacijsko sredstvo izkazala morska voda. PLA se je najbolj degradirala v modelni vodi s pH vrednostjo 10.
S pomočjo standardnega testa za določanje toksičnosti smo prav tako potrdili, da je med petimi preučevanimi materiali MERFIB najbolj nagnjen k fragmentaciji zaradi njegove vlaknaste strukture.
Ključne besede: plastični materiali, fragmentacija, polietilen tereftalat, recikliran polietilen tereftalat, vlakna polietilen tereftaltata, polilaktična kislina, vlakna melaminske eterificirane smole
Objavljeno v DKUM: 01.03.2023; Ogledov: 660; Prenosov: 47
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8. Sinteza in uporaba maghemitnih nanodelcev funkcionaliziranih s polisaharidom za adsorpcijo elementov redkih zemelj : magistrsko deloMatjaž Rantaša, 2022, magistrsko delo Opis: Magistrsko delo zajema sintezo magnetnih maghemitnih nanodelcev (MND), njihovo površinsko funkcionalizacijo s polisaharidom hondroitin sulfatom (HS) in raziskavo adsorpcije neodimovih (III) ionov (Nd3+) na magnetne nanoadsorbente. Namen magistrske naloge je bil ustvariti stabilne adsorbente, ki bi služili za vezavo in nadaljnjo regeneracijo elementov redkih zemelj (REE) iz vodnih raztopin. Magnetne nanoadsorbente smo karakterizirali s Fourierjevo transformirano infrardečo spektroskopijo na oslabljeni totalni odboj (ATR-FTIR), termogravimetrično analizo (TGA), dinamičnim sipanjem laserske svetlobe (DLS), X-žarkovno fotoelektronsko spektroskopijo (XPS), rentgensko praškovno difrakcijo (XRD), transmisijsko elektronsko mikroskopijo (TEM) in masno spektrometrijo sekundarnih ionov z analizatorjem na čas preleta (ToF-SIMS). Izvedene so bile magnetne meritve, meritve zeta potenciala, meritve skupnega organskega ogljika (TOC), naredili smo polielektrolitsko titracijo HS. Adsorpcijo nevezanega Nd3+ v supernatantu smo po odstranitvi magnetnih nanoadsorbentov merili z UV-VIS spektroskopijo. Tekom meritev smo preverjali vpliv kontaktnega časa, pH delovne raztopine in vpliv mase uporabljenega nanoadsorbenta. V tem magistrskem delu so zbrani podatki vseh sintez in funkcionalizacij, ki so bile izvedene. Podrobno so razloženi rezultati karakterizacij, podana je diskusija adsorpcije z vsemi slikami, grafi in tabelami, ki so nastale med izvajanjem eksperimentalnega dela. Rezultati kažejo, da se na funkcionalizirane MND adsorbirajo Nd3+, vendar sama metoda UV-VIS ni primerna za meritve adsorpcije v danem koncentracijskem območju delovnih raztopin in določitev adsorpcijske kapacitete.
Ključne besede: maghemitni nanodelci, hondroitin sulfat, neodim, adsorpcija, UV-VIS spektroskopija
Objavljeno v DKUM: 09.09.2022; Ogledov: 833; Prenosov: 233
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9. Funkcionalizacija zaščitnih mask z uporabo naravnih snovi : diplomsko delo visokošolskega strokovnega študijskega programa I. stopnjeMaša Vračevič, 2022, diplomsko delo Opis: Zaščitne maske filtrirajo mikrobne delce in ščitijo uporabnika pred škodljivimi delci. Ključnega pomena za zaščito uporabnika in ljudi v njegovi okolici je zaščita pred nalezljivimi boleznimi. V ta namen je potrebna uporaba protimikrobnih sredstev, kot sta laktoferina in katehin.Za lažji nanos na površino maske smo pripravili raztopini, ki smo ju s pršenjem nanesli na notranjo površino sloja maske iz polipropilena (PP).
Prisotnost potencialnih antiviralnih agensov na površini smo določili z gravimetrično tehniko tehtanja vzorcev pred in po pršenju, s spektroskopskimi metodami in z merjenjem naboja na površini s tehniko določanja zeta potenciala. Pri metodi x-žarkovne rentgenske spektroskopije (XPS) smo določali elementno sestavo na podlagi fotoefekta. Prisotnost agensov smo potrdili, če je bil na površini prisoten element, ki ni izhajal iz polipropilena. Z metodo infrardeče spektroskopije s Fourierjevo transformacijo (ATR-FTIR) smo na podlagi sevanja infrardeče svetlobe v spektrometru dobili spektre. Vrhove spektrov laktoferina in katehina smo primerjali z dobljenimi spektri vzorcev in v primeru ujemanja vrhov določili prisotnost nanešenih agensov na površini. Da smo preverili kemijsko stabilnost vzorcev po simulaciji človeške sape, smo ponovno uporabili gravimetrično tehniko tehtanja in spektroskopsko metodo ATR-FTIR. Za določanje omočljivosti modificirane površine smo uporabili metodo goniometrije, kjer smo z doziranjem kapljic na površino izmerili stične kote. Zračno prepustnost vzorcev smo merili na podlagi različnih tlakov na napravi Karl Shroder KG air permeability tester. Protimikrobno delovanje površine vzorcev pa smo določili s testi antiviralnosti na petrijevkah.
Analize, ki so bile narejene za dokaz prisotnosti slojev laktoferina in katehina na površini, so v večini pokazale prisotnost raztopine laktoferina. Sloj katehina ni bil prisoten na površini vzorca glede na rezultate merjenja zeta potenciala in spektrov dobljenih pri metodi ATR-FTIR. Prisotnost posameznih slojev nanosa pa je bila zaznana pri rezultatih antiviralnosti. Ti so pokazali, da v primeru popršenih vzorcev zunanjega sloja maske pride do redukcije oziroma zmanjšanja nastajanja modelnih virusov v primerjavi z nepopršenim materialom. Izmerjeni stični koti so pokazali, da imamo hidrofobno površino vzorcev, kar zagotavlja manjšo omočlljivost materiala. Z določanjem zračne prepustnosti smo želeli dokazati, da material omogoča zadostno prepustnost zraka, če na površino materiala nanesemo sloje antiviralnih agensov.
Ključne besede: polipropilen, laktoferin, katehin, antiviralnost, spektroskopija
Objavljeno v DKUM: 05.09.2022; Ogledov: 786; Prenosov: 138
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10. Izolacija keratina iz odpadne biomase in sinteza keratinskih nanodelcev : diplomsko delo univerzitetnega študijskega programa I. stopnjeAnja Mešl, 2021, diplomsko delo Opis: Piščančje perje, ki je odpadna biomasa, predstavlja do 10 % celotne piščančje suhe mase. Iz tega vidika ima veliko potencialnih industrijskih aplikacij, pri tem pa tudi zmanjšamo količino odpadne biomase in vplivamo pozitivno na okoljski vidik. Skoraj v celoti je perje sestavljeno iz proteina keratina. Ker pa je keratin netopen v vodi, je njegova ekstrakcija zahtevna naloga. Večina dosedanjih procesov ekstrakcije je okolju neprijaznih in neekonomičnih. Raziskave torej vodijo v iskanje bolj zelenih in ekonomičnih procesov. V diplomski nalogi smo se odločili za okolju prijazen hidrotermični proces; ekstrakcijo keratina v subkritični vodi. Ekstrakcijo z vodo smo izvedli pri 180 °C in času 1h (2 g perja v 70 mL vode). Rezultati kažejo, da je naša suspenzija vsebovala keratin, katerega molekulske mase so bile v območju od 4,6 do 15 kDa. Z metodo ATR-FTIR smo potrdili prisotnost proteina keratina v ekstraktu. V nadaljevanju smo iz izoliranega keratina z alginatom, hitozanom in TPP z metodo kompleksacije in ionske gelacije sintetizirali delce, ki pa niso bili v nano območju tako, kot smo predvidevali. Sintetizirani delci so bili mikronskih velikosti in predstavljajo mikrodelce, ki smo jih analizirali. V njih smo nato ujeli zdravilo in določili kinetiko sproščanja. Ugotovili smo, da keratinske delce lahko uporabimo kot dostavni sistem za kontrolirano sproščanje učinkovin. Z nadaljnjo optimizacijo postopkov bi v prihodnosti lahko sintetizirali nanodelce.
Ključne besede: keratin, nanodelci, hidrotermični procesi, ekstrakcija v subkritični vodi, kompleksacija, perje
Objavljeno v DKUM: 22.09.2021; Ogledov: 867; Prenosov: 138
Celotno besedilo (3,04 MB) |
