1. Sustainable cyclodextrin modification and alginate incorporation: viscoelastic properties, release behavior, and morphology in bulk and microbead hydrogel systemsMaja Čič, Nejc Petek, Iztok Dogša, Andrijana Damjanović, Boštjan Genorio, Nataša Poklar Ulrih, Ilja Gasan Osojnik Črnivec, 2025, original scientific article Abstract: Incorporating cyclodextrins (CDs) into ionically crosslinked polysaccharide matrices offers a promising strategy for developing well-defined, safe-by-design and biocompatible carrier systems with tunable rheological properties. In this study, β-cyclodextrin (β-CD) was functionalized with citric acid (CDC) and maleic anhydride (CDM) using solvent-free synthesis to improve compatibility with alginate hydrogels. The modified CDs were characterized by FTIR, 1H NMR, DLS, zeta potential, and MS, confirming successful esterification (4.0 and 3.4 –OH substitution for CDC and CDM, respectively) and stable aqueous dispersion. Rheological measurements showed that native CD accelerated gelation (within approximately 30 s), while CDC and CDM delayed crosslinking (by 2 to 13 min) and reduced gel strength, narrowing the linear viscoelastic range to 0.015–0.089% strain due to competition between polycarboxylated CDs and alginate chains for Ca2+ ions. Vibrational prilling produced alginate microbeads with diameters of 800–1000 µm and a simultaneous increase in size and CD concentration. Hydrogels demonstrated high CD retention (>80% after 28 h) and slightly greater release of CDC and CDM than native CD. Overall, solvent-free modification of CDs with citric and maleic acids provides a sustainable approach to tailoring the gelation kinetics, viscoelasticity, and release behavior of alginate-based hydrogels, offering a versatile, food- and health-compliant platform for controlled delivery of bioactive compounds.
Keywords: cyclodextrin, alginate, dry modification, solvent-free, hydrogels, viscoelasticity, rheometry, microcarrier design
Published in DiRROS: 25.11.2025; Views: 861; Downloads: 152
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2. Stabilisation of lutein and lutein esters with polyoxyethylene sorbitan monooleate, medium-chain triglyceride oil and lecithinZala Gombač, Ilja Gasan Osojnik Črnivec, Mihaela Skrt, Katja Istenič, Andreja Knez Knafelj, Igor Pravst, Nataša Poklar Ulrih, 2021, original scientific article Published in DiRROS: 11.11.2025; Views: 254; Downloads: 163
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3. Nano spray-dried particles of in-situ crosslinked alginate and their toxicological characterisationJaka Levanič, Ilja Gasan Osojnik Črnivec, Iza Rozman, Mihaela Skrt, Alja Štern, Bojana Žegura, Nataša Poklar Ulrih, 2024, original scientific article Abstract: The feasibility and technical capacity for producing crosslinked sub-micron gels with a nano spray-dryer were studied with variable pH systems incorporating alginate, pectin, and pullulan. The obtained powders were characterized for their morphology, particle size distribution, and their toxicological safety profile using genotoxicity and cytotoxicity assays. Additionally, quercetin was added to the encapsulation system to study the potential of the system to encapsulate this material. The produced powders exhibited morphologies and particle size distributions characteristic for nano spray-drying. The addition of pullulan and pectin to the feed solutions resulted in a particle size increase, with crosslinked alginate particles having a mean value of 1.43 μm, while particles with added pectin and pullulan had a mean particle size of 1.70 and 1.75 μm, respectively. The inclusion of quercetin proved to be problematic with this encapsulation system. Extremely high degradation rates and extremely low encapsulation efficiencies were observed due to the alkaline pH (~10) of the system that is needed to keep the feed dispersion in a liquid state and prevent premature crosslinking of the alginate. Although pectin and pullulan provided some protection for quercetin in the alkaline dispersion, the absolute quercetin content in the final product remained very low, with a maximum achieved encapsulation efficiency of 2.06 %. The safety profile of most produced powders was favourable, as they did not exhibit any significant cytotoxic and genotoxic activity in the HepG2 cell line, except in the case of Alginate/Pullulan which showed a 43 % decrease in cell viability at 500 μg/mL. Samples where quercetin was added did not show any increased toxicological effect.
Keywords: alginate, polysaccharides, crosslinking, nano spray drying, toxicological evaluation
Published in DiRROS: 08.05.2025; Views: 853; Downloads: 527
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4. Ovrednotenje in karakterizacija biomaseDarja Stare, Špela Ščap, Rok Mihelič, Sara Mavsar, Mateja Mešl, Miha Humar, Ilja Gasan Osojnik Črnivec, Nina Barbara Križnik, Blaž Likozar, Primož Oven, Luka Juvančič, 2020, treatise, preliminary study, study Keywords: biogospodarstvo, biomasa, razpoložljivost biomase, izkoriščenost potencialov
Published in DiRROS: 16.03.2021; Views: 2304; Downloads: 1099
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6. The hazard assessment of nanostructured CeO [sub] 2-based mixed oxides on the zebrafish Danio rerio under environmentally relevant UV-A exposureAnita Jemec Kokalj, Petar Djinović, Ilja Gasan Osojnik Črnivec, Albin Pintar, 2015, original scientific article Abstract: The effect of nanomaterials on biota under realistic environmental conditions is an important question. However, there is still a lack of knowledge on how different illumination conditions alter the toxicity of some photocatalytic nanomaterials. We have investigated how environmentally relevant UV-A exposure (intensity 8.50 ± 0.61 W/m2, exposure dose 9.0 J/cm2) affected the toxicity of cerium oxide (CeO2)-based nanostructured materials to the early-life stages of zebrafish Danio rerio. Pure cerium oxide (CeO2), copper–cerium (CuO–CeO2) (with a nominal 10, 15 and 20 mol.% CuO content), cerium–zirconium (CeO2–ZrO2) and nickel and cobalt (Ni–Co) deposited over CeO2–ZrO2 were tested. It was found that under both illumination regimes, none of the tested materials affected the normal development or induced mortality of zebrafish early-life stages up to 100 mg/L. Only in the case of CuO–CeO2, the growth of larvae was decreased (96 h LOEC values for CuCe10, CuCe15 and CuCe20 were 50, 50 and 10 mg/L, respectively). To conclude, CeO2-based nanostructured materials are not severely toxic to zebrafish and environmentally relevant UV-A exposure does not enhance their toxicity.
Keywords: Nickel cobalt nanocrystalline catalysts, UV-A phototoxicity, UV-shielding, zebrafish
Published in DiRROS: 16.12.2014; Views: 10661; Downloads: 1115
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