1. Antimicrobial activity of amino-modified cellulose nanofibrils decorated with silver nanoparticlesVesna Lazić, Jovan Nedeljković, Vanja Kokol, 2024, izvirni znanstveni članek Opis: Silver nanoparticles (Ag NPs) conjugated with amino-functionalized cellulose nanofibrils (NH2−CNFs) were in situ-prepared by reducing silver ions with free amino groups from NH2−CNFs. The spectroscopy and transmission electron microscopy measurements confirmed the presence of non-agglomerated nanometer-in-size Ag NPs within micrometer-large NH2−CNFs of high (20 wt.-%) content. Although the consumption of amino groups during the formation of Ag NPs lowers the ζ-potential and surface charge of prepared inorganic–organic hybrids (from +31.3 to +19.9 mV and from 2.4 to 1.0 mmol/g at pH 7, respectively), their values are sufficiently positive to ensure electrostatic interaction with negatively charged cell walls of pathogens in acidic and slightly (up to pH ~8.5) alkaline solutions. The antimicrobial activity of hybrid microparticles against various pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans) is comparable with pristine NH2−CNFs. However, a long-timescale use of hybrids ensures the slow and controlled release of Ag+ ions to surrounding media (less than 1.0 wt.-% for one month).
Ključne besede: amino-modified cellulose nanofibrils, silver nanoparticles, hybrid microparticles, zeta-potential, antimicrobial activity
Objavljeno v DKUM: 09.12.2024; Ogledov: 0; Prenosov: 0
 Celotno besedilo (3,84 MB)
Gradivo ima več datotek! Več... |
2. PREPARATION OF AMINO ACID AND PEPTIDE POLYSACCHARIDE DERIVATIVES AND THEIR APPLICATION AS BIOMATERIALS : doctoral dissertationAna Bratuša, 2024, doktorska disertacija Opis: The derivatization of the polysaccharide dextran with N-protected amino acids (Boc-L-Phenylalanine, BocGlycine, Boc-L-Cysteine, and Boc-L-Cysteine-S-Trt) and peptides (Boc-L-DiPhenylalanine, Boc DiGlycine, and 2,5-diketopiperazine) as the basis for biomaterial preparation is presented in this Doctoral Dissertation. Such prepared dextran derivatives are intended to mimic the proteoglycan complex (PGs), one of the most important structural and functional biomacromolecules in the extracellular matrix (ECM) of tissue. Nowadays, developments in biomaterials are focusing increasingly on the preparation and use of biomimetic molecular structures to achieve positive results in tissue engineering (TE) and drug delivery. Designing and synthesizing these biomimetic materials, however, requires sophisticated chemical and material preparation methods, knowledge that is, currently, unexplored.
In this work, we developed a suitable procedure for dextran derivatization, and investigated the most optimal reaction or deprotection conditions (temperature and time) and isolation/purification methods. The structures of the obtained BocPhe-Dex, BocGly-Dex, BocCys-Dex, and BocSTLC-Dex were analyzed with FTIR, NMR, SEC-MALS, and EA. The results showed that dextran derivatization was successful in all cases except in the case of dextran derivatization with BocCys. Investigation of the effect of the derivatization conditions and purification on the stability, purity, and other important chemical and physical properties of the obtained product, showed that the temperature and time of derivatization do not have a bigger effect on the products' properties, while the purification method, on the other hand, has. Its effect is visible in the product's purity and mass yields of products prepared under the same reaction conditions.
Derivatization of dextran with peptides (Boc-L-DiPhenylalanine, BocDiGlycine, and 2,5-diketopiperazine) was performed using the CDI coupling agent or Amberlite-IR 120 as a catalyst. The products were analyzed with FTIR and 1H and 13C NMR. The results showed successful dextran derivatization in the case of BocDiPhenylalanine and BocDiGlycine, while, in the case of 2,5-diketopiperazine, a reaction covalent bond with the dextran was not confirmed.
BocPhe-Dex and BocSTLC-Dex were selected as the most optimal amino acid-dextran derivatives for further preparation of 3D formulations in the shape of nanoparticles (NPs). Nanoparticles were prepared with the emulsion/solvent evaporation method from the obtained BocPhe-Dex and BocSTLC-Dex products (prepared in the first stage of this Doctoral Dissertation). SEM analysis showed that the prepared NPs were homogeneous and nicely spherical, with an average dry diameter of 325 ± 118 nm in the case of BocSTLC-Dex, and 1039 ± 382 nm in the case of NPs prepared from BocPhe-Dex. All the prepared NPs retained their proper spherical shape and stability during the acidic treatment, and so confirmed their potential for further functionalization and applications for drug delivery. The BocSTLC-Dex NPs were also evaluated with cell viability tests, which showed that the prepared NPs were not cytotoxic, one of the most important characteristics for the drug delivery applications of NPs.
This work serves as a basis for further studies on the derivatization of polysaccharides with amino acids and peptides, and their application in tissue engineering or drug delivery.
Ključne besede: Amino Acid-Dextran derivatives, Peptide-Dextran derivatives, Proteoglycan complex, 3D formulation, Nanoparticles, Drug delivery
Objavljeno v DKUM: 18.10.2024; Ogledov: 0; Prenosov: 10
Celotno besedilo (9,08 MB) |
3. Structure and potential application of surfactant-free microemulsion consisting of heptanol, ethanol and waterMartina Gudelj, Marina Kranjac, Lucija Jurko, Matija Tomšič, Janez Cerar, Ante Prkić, Perica Bošković, 2024, izvirni znanstveni članek Opis: Microemulsions, which are thermodynamically stable and isotropic mixtures of water, oil, and surfactants, attract significant research interest due to their unique physicochemical properties and diverse industrial applications. Traditional surfactant-based microemulsions (SBMEs) stabilize the interface between two typically immiscible liquids, forming various microstructures such as oil-in-water (O/W) droplets, water-in-oil (W/O) droplets, and bicontinuous phases. However, the use of surfactants poses environmental concerns, cost implications, and potential toxicity. Consequently, there is increasing interest in developing surfactant-free microemulsions (SFMEs) that offer similar benefits without the drawbacks associated with surfactants. In this study, we explore the formation and characteristics of a new surfactant-free microemulsion in a ternary system comprising water, ethanol, and heptanol. Advanced techniques are employed to characterize the microstructures and stability of surfactant-free microemulsions. These include electrical conductivity measurements, surface tension analysis, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). These methods have been extensively used in previous research on surfactant-free microemulsions (SFMEs) to reveal the properties and interactions within microemulsion systems. The area of interest is identified using these techniques, where silica nanoparticles are subsequently synthesized and then visualized using transmission electron microscopy (TEM).
Ključne besede: surfactant-free microemulsions, ternary system, nanoparticles
Objavljeno v DKUM: 03.10.2024; Ogledov: 0; Prenosov: 5
Celotno besedilo (3,20 MB)
Gradivo ima več datotek! Več... |
4. Films based on TEMPO-oxidized chitosan nanoparticles: Obtaining and potential application as wound dressingsMatea Korica, Katarina Mihajlovski, Tamilselvan Mohan, Mirjana M. Kostić, 2024, izvirni znanstveni članek Opis: A series of novel films based on TEMPO-oxidized chitosan nanoparticles were prepared by casting method.
Fourier transform infrared spectroscopy (FTIR) was employed to ascertain the chemical structure of TEMPOoxidized chitosan. The surface morphology of the TEMPO-oxidized chitosan nanoparticles was analyzed by
atomic force microscopy (AFM). The physicochemical (area density, thickness, iodine sorption, roughness),
functional (moisture sorption, liquid absorption capacity, weight loss upon contact with the liquid, and water
vapor transmission rate), antibacterial, and antioxidant properties of films based on TEMPO-oxidized chitosan
nanoparticles were also investigated. The physicochemical properties of the films varied widely: area density
ranged from 77.83 ± 0.06 to184.46 ± 0.05 mg/cm2
, thickness varied between 80.5 ± 1.6 and 200.5 ± 1.6 μm,
iodine sorption spanned from 333.7 ± 2.1 to166.4 ± 2.2 mg I2/g, and roughness ranged from 4.1 ± 0.2 to 5.6 ±
0.3 nm. Similarly, the functional properties also varied significantly: moisture sorption ranged from 4.76 ± 0.03
to 9.62 ± 0.11 %, liquid absorption capacity was between 129.04 ± 0.24 and 159.33 ± 0.73 % after 24 h, weight
loss upon contact with the liquid varied between 31.06 ± 0.35 and 45.88 ± 0.58 % after 24 h and water vapor
transmission rate ranged from 1220.10 ± 2.91to1407.77 ± 5.22 g/m2 day. Despite the wide variations in
physicochemical and functional properties, all films showed maximum bacterial reduction of Staphylococcus
aureus and Escherichia coli, although they exhibited low antioxidant activity. The results suggest that the films
could be effectively utilized as antibacterial wound dressings.
Ključne besede: TEMPO-oxidized chitosan nanoparticles, films, antibacterial activity, wound dressings
Objavljeno v DKUM: 11.09.2024; Ogledov: 56; Prenosov: 25
Celotno besedilo (4,92 MB)
Gradivo ima več datotek! Več... |
5. Characterization of germanium nanoparticles from arylgermanium trihydridesPhilipp Schmid, Brigitte Koppelhuber-Bitschnau, Matjaž Finšgar, Ilse Letofsky-Papst, Johannes Rattenberger, Robert Saf, 2024, izvirni znanstveni članek Ključne besede: nanoparticles, germanium, optical properties, electronic properties
Objavljeno v DKUM: 29.08.2024; Ogledov: 74; Prenosov: 3
 Povezava na datoteko |
6. Multifunctional iron oxide nanoparticles as promising magnetic biomaterials in drug elivery : a ǂreviewKatja Vasić, Željko Knez, Maja Leitgeb, 2024, pregledni znanstveni članek Ključne besede: multifunctional biomaterials, bio-composites, nanocarriers, magnetic nanoparticles, modification, drug delivery
Objavljeno v DKUM: 20.08.2024; Ogledov: 72; Prenosov: 3
Celotno besedilo (5,66 MB) |
7. Thermal study of APTES-functionalized magnetite nanoparticles with citric acid and polyacrylic acid for advanced forward osmosis systemsMatjaž Kristl, Urška Ostroško, Irena Ban, Irena Petrinić, Janja Stergar, 2024, izvirni znanstveni članek Opis: Iron-based magnetic nanoparticles (MNPs) have attracted considerable attention as promising draw solutes in forward osmosis processes due to various advantages. In the present study, magnetite (Fe3O4) nanoparticles (MNPs) with diameters in the range of 12±2 nm were synthesized by applying the coprecipitation method and stabilized using (3-aminopropyl) triethoxysilane (APTES). The amino groups of APTES were further functionalized with various amounts of citric acid (CA) and poly(acrylic acid) (PAA) to achieve higher osmotic pressure. The as-prepared and functionalized nanoparticles were characterized using diferent methods: Fourier-transform infrared spectroscopy (FTIR) confrmed the binding of APTES and CA/PAA on the surface of the MNPs, while the size of the particles was determined by transmission electron microscopy (TEM) and X-ray powder difraction. The isoelectric point, zeta potential, and the particle size in suspension were determined by dynamic light scattering (DLS)/zeta potential measuring system. The amount of free –COOH groups was determined by conductometric titrations. The amount of organic matter (APTES, CA, and PAA) bound on the surface was determined by thermogravimetric analysis (TG), giving results between 7.6% for samples stabilized with APTES only and 17.5% for samples functionalized with APTES+PAA. TG provides a simple and efcient method for determining the amount of organic compounds bound to the surface of MNPs. The osmotic pressure measurements of double-layer coated MNPs provided encouraging results of up to 28 bar, enabling using the samples as draw solutions in an experimental forward osmosis system.
Ključne besede: magnetic nanoparticles, magnetite, citrit acid, poly(acrylic acid), forward osmosis
Objavljeno v DKUM: 14.08.2024; Ogledov: 105; Prenosov: 5
Celotno besedilo (2,04 MB) |
8. Experimental advances in nanoparticle-driven stabilization of liquid-crystalline blue phases and twist-grain boundary phasesGeorge Cordoyiannis, Marta Lavrič, Vasileios Tzitzios, Maja Trček, Ioannis Lelidis, George Nounesis, Samo Kralj, Jan Thoen, Zdravko Kutnjak, 2021, pregledni znanstveni članek Opis: Recent advances in experimental studies of nanoparticle-driven stabilization of chiral liquid-crystalline phases are highlighted. The stabilization is achieved via the nanoparticles’ assembly in the defect lattices of the soft liquid-crystalline hosts. This is of significant importance for understanding the interactions of nanoparticles with topological defects and for envisioned technological applications. We demonstrate that blue phases are stabilized and twist-grain boundary phases are induced by dispersing surface-functionalized CdSSe quantum dots, spherical Au nanoparticles, as well as MoS2 nanoplatelets and reduced-graphene oxide nanosheets in chiral liquid crystals. Phase diagrams are shown based on calorimetric and optical measurements. Our findings related to the role of the nanoparticle core composition, size, shape, and surface coating on the stabilization effect are presented, followed by an overview of and comparison with other related studies in the literature. Moreover, the key points of the underlying mechanisms are summarized and prospects in the field are briefly discussed.
Ključne besede: liquid crystals, nanoparticles, quantum dots, reduced-graphene oxide, calorimetry, microscopy, blue phases, twist-grain boundary phases, disclination lines, screw dislocations
Objavljeno v DKUM: 09.08.2024; Ogledov: 97; Prenosov: 9
Celotno besedilo (8,25 MB)
Gradivo ima več datotek! Več... |
9. 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: 15
Celotno besedilo (892,02 KB)
Gradivo ima več datotek! Več... |
10. |
