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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: 132; Prenosov: 2
.pdf Celotno besedilo (4,24 MB)
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Colloidal solutions as advanced coatings for active packaging development: focus on PLA systems
Athira John, Klementina Pušnik Črešnar, Dimitrios Bikiaris, Lidija Fras Zemljič, 2023, pregledni znanstveni članek

Ključne besede: food packaging, active packaging, colloids, PLA
Objavljeno v DKUM: 11.04.2024; Ogledov: 104; Prenosov: 1
.pdf Celotno besedilo (13,52 MB)
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Advance analysis of the obtained recycled materials from used disposable surgical masks
Alen Erjavec, Julija Volmajer Valh, Silvo Hribernik, Tjaša Kraševac Glaser, Lidija Fras Zemljič, Tomaž Vuherer, Branko Neral, Mihael Brunčko, 2024, izvirni znanstveni članek

Opis: The production of personal protective equipment (PPE) has increased dramatically in recent years, not only because of the pandemic, but also because of stricter legislation in the field of Employee Protection. The increasing use of PPE, including disposable surgical masks (DSMs), is putting additional pressure on waste collectors. For this reason, it is necessary to find high-quality solutions for this type of waste. Mechanical recycling is still the most common type of recycling, but the recyclates are often classified as low-grade materials. For this reason, a detailed analysis of the recyclates is necessary. These data will help us to improve the properties and find the right end application that will increase the value of the materials. This work represents an extended analysis of the recyclates obtained from DSMs, manufactured from different polymers. Using surface and morphology tests, we have gained insights into the distribution of different polymers in polymer blends and their effects on mechanical and surface properties. It was found that the addition of ear loop material to the PP melt makes the material tougher. In the polymer blends obtained, PP and PA 6 form the surface (affects surface properties), while PU and PET are distributed mainly inside the injection-molded samples.
Ključne besede: mechanical recycling, disposable surgical mask, morphology, surface properties, mechanical properties, nonwoven materials, PPE
Objavljeno v DKUM: 09.04.2024; Ogledov: 115; Prenosov: 4
.pdf Celotno besedilo (8,08 MB)
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Fabrication of poly(ethylene furanoate)/silver and titanium dioxide nanocomposites with improved thermal and antimicrobial properties
Johan Stanley, Eleftheria Xanthopoulou, Lidija Fras Zemljič, Panagiotis A. Klonos, Apostolos Kyritsis, Dimitra A. Lambropoulou, Dimitrios Bikiaris, 2024, izvirni znanstveni članek

Opis: Poly(ethylene furanoate) (PEF)-based nanocomposites were fabricated with silver (Ag) and titanium dioxide (TiO2) nanoparticles by the in-situ polymerization method. The importance of this research work is to extend the usage of PEF-based nanocomposites with improved material properties. The PEF-Ag and PEF-TiO2 nanocomposites showed a significant improvement in color concentration, as determined by the color colorimeter. Scanning electron microscopy (SEM) photographs revealed the appearance of small aggregates on the surface of nanocomposites. According to crystallinity investigations, neat PEF and nanocomposites exhibit crystalline fraction between 0–6%, whereas annealed samples showed a degree of crystallinity value above 25%. Combining the structural and molecular dynamics observations from broadband dielectric spectroscopy (BDS) measurements found strong interactions between polymer chains and nanoparticles. Contact angle results exhibited a decrease in the wetting angle of nanocomposites compared to neat PEF. Finally, antimicrobial studies have been conducted, reporting a significant rise in inhibition of over 15% for both nanocomposite films against gram-positive and gram-negative bacteria. From the overall results, the synthesized PEF-based nanocomposites with enhanced thermal and antimicrobial properties may be optimized and utilized for the secondary packaging (unintended food-contact) materials.
Ključne besede: active agents, antimicrobial studies, biobased polymers, crystallinity, poly(ethylene 2, 5-furandicarboxylate)
Objavljeno v DKUM: 03.04.2024; Ogledov: 103; Prenosov: 2
.pdf Celotno besedilo (3,13 MB)
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Eco-finishing of cotton with chitosan and giant goldenrod (Solidago gigantea Aiton) aqueous extract for development of antioxidant and UV protective textiles
Sebastijan Šmid, Anja Verbič, Lidija Fras Zemljič, Marija Gorjanc, 2023, izvirni znanstveni članek

Opis: Giant goldenrod (S. gigantea Aiton) is considered an invasive weed in Europe, Asia, Australia, and New Zealand. In this research, the untreated and chitosan-treated cotton fabrics were functionalized with goldenrod inflorescences aqueous extract, at room temperature and 95°C. Zeta potential of fabrics was determined as a function of pH and the results showed an increased isoelectric point from 2.50 to 5.25 and amphoteric character of the chitosan-treated sample. The antioxidant activity (AA) of extract and functionalized fabrics was determined using DPPH analysis, while color and ultraviolet protection factor (UPF) were determined spectroscopically before and after wash and lightfastness testing. The chitosan pretreatment and dyeing of cotton at higher temperature increased AA (from 41.19 ± 0.28 to 56.08 ± 0.25), UPF (from 33.05 to 51.59) and color strength (K/S) (from 1.74 to 2.21), providing dyed cotton with excellent UV protection and a free radical inhibition activity. The samples had good wash fastness in terms of color (ΔEab* < 1), but not in terms of UV protection (UPF value decreased after washing to 23.47). The overall lightfastness was good to excellent (the UPF values of chitosan and dyed samples did not change much after lightfastness test (UPF = 51.75).
Ključne besede: Goldenrod, invasive plant, eco-functionalisation, cotton, antioxidant activity, UV protection
Objavljeno v DKUM: 25.03.2024; Ogledov: 126; Prenosov: 6
.pdf Celotno besedilo (1,89 MB)
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Funkcionalizacija tekstilij z izoliranimi gradniki jajčnih lupin in izdelava nanovlaken iz le - teh : magistrsko delo
Rosvita Pliberšek, 2024, magistrsko delo

Opis: 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.
Ključne besede: jajčne lupine, hidroliza, funkcionalizacija, izolirani gradniki, PES in bombažne tekstilije, ognjevarnost, medicinske tekstilije, UV zaščita
Objavljeno v DKUM: 22.03.2024; Ogledov: 167; Prenosov: 12
.pdf Celotno besedilo (3,18 MB)

Funkcionalizacija tekstilij z uporabo biopolimerov iz odpadnih mas : diplomsko delo
Vanessa Wendy Bračko, 2023, diplomsko delo

Opis: Diplomsko delo je usmerjeno v dokazovanje multifunkcionalnosti tekstilij, na katere so bile nanešene 4 apretirne raztopine, ekstrahirane iz odpadne biomase perutninskega perja in volne (ki vsebujeta biopolimer keratin) s pomočjo zelene hidrotermalne razgradnje. Polovica vzorcev je bila dodatno dializirana skozi dializno membrano. Najprej so bili določeni kemijski parametri in lastnosti ekstrahiranih raztopin (dializirana in nedializirana raztopina iz perja, dializirana in nedializirana raztopina iz volne), s poudarkom na sledenju biopolimeru keratinu. Po nanosu raztopin na poliestrsko tekstilijo, kot referenčno tekstilijo, je bila dokazana prisotnost teh raztopin na površini tkanine. Prav tako so bile analizirane nove multifunkcionalne lastnosti tekstilij. Najopaznejši doprinos k lastnostim se kaže v izjemnem antioksidativnem delovanju, ognjevarnosti, UV zaščiti in hidrofilnosti novih multifunkcionalnih tekstilij.
Ključne besede: keratin, biopolimer, perutninsko perje, volna, hidrotermalna razgradnja, multifunkcionalnost, tekstilije
Objavljeno v DKUM: 28.02.2024; Ogledov: 151; Prenosov: 9
.pdf Celotno besedilo (2,82 MB)

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