1. Alginate coatings suppress unspecific protein adhesion on PVCMatej Bračič, Alenka Vesel, Lidija Fras Zemljič, 2025, izvirni znanstveni članek Opis: This study involved oxygen plasma activation of PVC and its effect on alginate coating adhesion, analyzed using a quartz crystal microbalance with dissipation (QCM-D). The results demonstrated improved adhesion of alginate on plasma-activated PVC due to an increase of oxidized functional groups. Wettability measurements, conducted using optical contact angle goniometry and QCM-D, showed a significant increase in the wettability of PVC after alginate coating, with contact angles decreasing from 81.4 ± 1.1◦ to 37.3 ± 3.1◦ 3D-profilometry mapping revealed a uniform distribution of alginate on the PVC film. Real-time antifouling studies using QCM-D with two model proteins, bovine serum albumin and bovine fibrinogen, were performed to elucidate the surface interactions involved in protein inhibition. The results indicated a substantial reduction in protein adhesion on alginate-coated PVC. This reduction in protein adhesion is attributed to the high hydrophilicity of the alginate coatings and partial removal of the alginate, which together contribute to poor protein adhesion. This comprehensive approach advances the development of effective solutions for mitigating biofilm-related issues on PVC-based medical devices, offering significant implications for improving patient outcomes.
Ključne besede: alginate, coatings, polyvinyl chloride, biofouling, quartz crystal microbalance, protein adhesion
Objavljeno v DKUM: 10.03.2025; Ogledov: 0; Prenosov: 10
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2. Morphological, surface and thermal properties of polylactic acid foils, melamine-etherified resin, and polyethylene terephthalate fabric during (bio)degradation in soilOlivija Plohl, Alen Erjavec, Lidija Fras Zemljič, Alenka Vesel, Maja Čolnik, Mojca Škerget, Yee Van Fan, Lidija Čuček, Gregor Trimmel, Julija Volmajer Valh, 2023, izvirni znanstveni članek Ključne besede: plastic materials, (bio)degradation, soil, surface chemistry, thermal properties, surface zeta potential
Objavljeno v DKUM: 28.02.2025; Ogledov: 0; Prenosov: 6
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4. A method for the immobilization of chitosan onto urinary cathetersAlenka Vesel, Nina Recek, Rok Zaplotnik, Albert Kurinčič, Katja Kuzmič, Lidija Fras Zemljič, 2022, izvirni znanstveni članek Opis: A method for the immobilization of an antibacterial chitosan coating to polymeric urinary medical catheters is presented. The method comprises a two-step plasma-treatment procedure, followed by the deposition of chitosan from the water solution. In the first plasma step, the urinary catheter is treated with vacuum-ultraviolet radiation to break bonds in the polymer surface film and create dangling bonds, which are occupied by hydrogen atoms. In the second plasma step, polymeric catheters are treated with atomic oxygen to form oxygen-containing surface functional groups acting as binding sites for chitosan. The presence of oxygen functional groups also causes a transformation of the hydrophobic polymer surface to hydrophilic, thus enabling uniform wetting and improved adsorption of the chitosan coating. The wettability was measured by the sessile-drop method, while the surface composition and structure were measured by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Non-treated samples did not exhibit successful chitosan immobilization. The effect of plasma treatment on immobilization was explained by noncovalent interactions such as electrostatic interactions and hydrogen bonds.
Ključne besede: polymer, chitosan immobilization, adhesion, plasma-surface modification, biopolymers
Objavljeno v DKUM: 05.12.2024; Ogledov: 0; Prenosov: 3
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5. Efficient proper embedding of a daisy cubeAleksander Vesel, 2021, izvirni znanstveni članek Opis: For a set ▫$X$▫ of binary words of length ▫$h$▫ the daisy cube ▫$Q_h(X)$▫ is defined as the subgraph of the hypercube ▫$Q_h$▫ induced by the set of all vertices on shortest paths that connect vertices of ▫$X$▫ with the vertex ▫$0^h$▫. A vertex in the intersection of all of these paths is a minimal vertex of a daisy cube. A graph ▫$G$▫ isomorphic to a daisy cube admits several isometric embeddings into a hypercube. We show that an isometric embedding is proper if and only if the label ▫$0^h$▫ is assigned to a minimal vertex of ▫$G$▫. This result allows us to devise an algorithm which finds a proper embedding of a graph isomorphic to a daisy cube into a hypercube in linear time.
Ključne besede: daisy cube, partial cube, isometric embedding, proper embedding
Objavljeno v DKUM: 29.11.2024; Ogledov: 0; Prenosov: 3
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6. Linear algorithms for the Hosoya index and Hosoya matrix of a treeAleksander Vesel, 2021, izvirni znanstveni članek Opis: The Hosoya index of a graph is defined as the total number of its independent edge sets. This index is an important example of topological indices, a molecular-graph based structure descriptor that is of significant interest in combinatorial chemistry. The Hosoya index inspires the introduction of a matrix associated with a molecular acyclic graph called the Hosoya matrix. We propose a simple linear-time algorithm, which does not require pre-processing, to compute the Hosoya index of an arbitrary tree. A similar approach allows us to show that the Hosoya matrix can be computed in constant time per entry of the matrix.
Ključne besede: Hosoya index, Hosoya matrix, optimal algorithm
Objavljeno v DKUM: 18.10.2024; Ogledov: 0; Prenosov: 3
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7. Mutual-visibility sets in cartesian products of paths and cyclesDanilo Korže, Aleksander Vesel, 2024, izvirni znanstveni članek Opis: For a given graph G, the mutual-visibility problem asks for the largest set of vertices M ⊆ V (G) with the property that for any pair of vertices u, v ∈ M there exists a shortest u, v-path of G that does not pass through any other vertex in M. The mutual-visibility problem for Cartesian products of a cycle and a path, as well as for Cartesian products of two cycles, is considered. Optimal solutions are provided for the majority of Cartesian products of a cycle and a path, while for the other family of graphs, the problem is completely solved.
Ključne besede: mutual-visibility set, supermutual-visibility number, Cartesian product
Objavljeno v DKUM: 14.08.2024; Ogledov: 73; Prenosov: 14
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8. 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: 28
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9. Binary coding of resonance graphs of catacondensed polyhexesAleksander Vesel, 2023, izvirni znanstveni članek Opis: A catacondensed polyhex H is a connected subgraph of a hexagonal system such that any edge of H lies in a hexagon of H, any triple of hexagons of H has an empty intersection and the inner dual of H is a cactus graph. A perfect matching M of a catacondensed polyhex H is relevant if every cycle of the inner dual of H admitsa vertex that corresponds to the hexagon which contributes three edges in M. The vertex set of the graph R˜(H) consists of all relevant perfect matchings of H, two perfect matchings being adjacent whenever their symmetric difference forms the edge set of a hexagon of H. A labeling that assigns in linear time a binary string to every relevant perfect matching of a catacondensed polyhex is presented. The introduced labeling defines an isometric embedding of R˜(H)
into a hypercube.
Ključne besede: graphs, graph theory, resonance graphs
Objavljeno v DKUM: 07.06.2024; Ogledov: 99; Prenosov: 14
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10. 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: 22
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