1. Bacterial nanocellulose biohybrid membranes and beads for potential cosmetics, food, and drug delivery applicationsKaja Kupnik, Neža Brezovec, Željko Knez, Maja Leitgeb, Mateja Primožič, 2026, izvirni znanstveni članek Opis: Bacterial nanocellulose is a promising biomaterial extensively used in functional foods and for drug delivery. Moreover, its characteristics can further be potentialized whether coupled with natural bio-extracts to endow antibacterial activity. Persea americana or avocado seed extracts are rich in phytochemicals and have demonstrated their antioxidant, antimicrobial and enzymatic activities, therefore encapsulating them into bacterial nanocellulose (BNC) may offer a potential release system of antibacterial avocado seed compounds. Accordingly, this study explores the in-depth insight into the influence of different bacterial nanocellulose producing strains (Komagataeibacter hansenii and Komagataeibacter xylinus) and cultivation conditions (static and dynamic cultivation, fermentation time) on the bacterial nanocellulose productivity and characteristics. The obtained bacterial nanocellulose membranes and beads were characterized in terms of chemical structure, morphology and crystallinity. More profitable and productive K. xylinus was further selected for encapsulation (up to 72.89 mg) of avocado seed extracts into bacterial nanocellulose membranes and beads in order to comprehensively evaluate the kinetic release profiles and determine their antibacterial activity against Escherichia coli and Staphylococcus aureus. Results of the study show that the bacterial nanocellulose and avocado seed extracts biohybrids represent a promising immediate (up to 17.39 mg in 1 h) and sustained (up to 35.04 mg in 48 h) release systems. Kinetic release modeling and cytotoxicity assessments confirmed controlled release behavior and biocompatibility for safe antibacterial applications in cosmetics, functional foods and drug delivery. Ključne besede: bacterial nanocellulose beads, avocado seed extract, re-hydration, release, antibacterial activity Objavljeno v DKUM: 23.01.2026; Ogledov: 0; Prenosov: 0
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2. Macromolecular inks of nanocellulose-alginate for direct-ink-writing : functional scaffolds enriched with curcumin extractsGal Slaček, Tamilselvan Mohan, Petra Kotnik, Tobias Alexander Steindorfer, Marco Beaumont, Željko Knez, Maša Knez Marevci, Karin Stana-Kleinschek, 2026, izvirni znanstveni članek Opis: We present a scalable platform for the fabrication of multifunctional bioactive materials by integrating, polysaccharide-based matrices, green extraction and additive manufacturing. In this work, bioactive 3D-printed structures were fabricated using inks composed of nanofibrillated cellulose (NFC), alginate (Alg), and curcumin extracts. Bioactive compounds were efficiently recovered from turmeric via solvent-free supercritical carbon dioxide extraction, yielding up to 6.57 mg/100 g curcuminoids and 232.45 mg/100 g total phenols. The extracts exhibited robust antioxidant activity (DPPH• IC50: 23.24 mg/mL; ABTS+• IC50: 3.59 mg/mL) and broad-spectrum antimicrobial efficacy against Staphylococcus aureus, Escherichia coli, Candida albicans, and Pseudomonas aeruginosa (MIC: 9.38 mg/mL). Incorporation into NFC-Alg inks exhibited excellent shear-thinning properties suitable for direct-ink-writing 3D printing. Post-printing CaCl2 crosslinking further reinforced the hydrogel network, enhancing mechanical robustness and shape fidelity. The resulting constructs featured a highly porous, grid-like architecture with intricate surface morphology, highlighting significant potential for biomedical and tissue engineering applications. Ključne besede: nanocellulose, alginate, curcumin extract, supercritical-CO2, antioxidant, antimicrobial properties, 3D-printing Objavljeno v DKUM: 08.12.2025; Ogledov: 0; Prenosov: 3
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3. Oxygen-generating and antibacterial xanthan gum/PLA aerogels loaded with dexamethasone for potential wound healingNika Atelšek Hozjan, Gabrijela Horvat, Matjaž Finšgar, Ana Iglesias-Mejuto, Inés Ardao Palacios, Carlos A. García-González, Željko Knez, Zoran Novak, 2025, izvirni znanstveni članek Opis: Chronic wounds do not heal within a reasonable time frame due to hypoxia and bacterial inflammation, creating an urgent need for advanced biomaterials to address these challenges. In this study, oxygen-generating, antibacterial xanthan gum-polylactic acid (XA/PLA) aerogels loaded with dexamethasone were developed for the first time for potential wound healing applications. The aerogels contained sodium percarbonate and calcium peroxide as oxygen-releasing agents, providing sustained oxygen release for up to 48 h. The aerogels had a highly porous structure with a high specific surface area (up to 396 ± 8 m2/g) and revealed high liquid absorption capacity in simulated body fluid, absorbing up to 67 times their original weight and remaining stable for 72 h. The in vitro release tests showed controlled profiles of dexamethasone over 24 h. The antibacterial tests demonstrated strong antibacterial activity against Escherichia coli (an up to 15.92 mm inhibition zone diameter) and Staphylococcus aureus (up to a 31.07 mm inhibition zone diameter). The in vitro biocompatibility assays revealed good cytocompatibility with mouse fibroblast cells (NIH/3T3), with a cell viability of >90%. Hemocompatibility tests showed no hemolytic activity with human blood (lysis rate <2%). Overall, these results emphasise the versatility of the XA/PLA aerogels and their potential for the treatment of chronic wounds. Ključne besede: wound healing, aerogels, xanthan gum Objavljeno v DKUM: 08.12.2025; Ogledov: 0; Prenosov: 3
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4. Sustainable extraction of hemp seed and formulation extracts into organogels with analytical profiling of fatty acidssubcritical fluids in food processingSara Karlovšek, Taja Žitek Makoter, Teo Makoter, Željko Knez, Maša Knez Marevci, 2025, izvirni znanstveni članek Opis: Sustainable extraction methods for natural extracts are crucial for mitigating environmental impact. Strategies that focus on waste reduction and resource efficiency contribute to long-term conservation. Hemp seeds, which were previously treated as waste product, are now valued for their nutrition and functional properties. This study investigated sustainable extraction methods for obtaining natural extracts from hemp seeds, with a focus on reducing environmental impact through efficient resource utilization and waste reduction. The extraction methods compared included supercritical fluid extraction (SFE), Soxhlet extraction (SOX), ultrasound-assisted extraction (UAE), cold maceration (CM), and cold pressing (CP). The contents of antioxidants, total phenols, and fatty acids in the extracts were analyzed via gas chromatography–mass spectrometry (GC–MS). The extracts were subsequently formulated into organogels to evaluate the stability of the fatty acids. The results showed that SFE and CP were the most efficient and environmentally friendly methods, with SFE allowing complete separation of the solvent from the extract. CP was also found to be effective and environmentally friendly. The study confirmed that formulating extracts in organogels effectively inhibited fatty acid oxidation, although a reduction in fatty acid content was observed during gel production. Overall, the formulation of extracts in organogels increased their stability, especially in preventing fatty acid degradation. Ključne besede: supercritical fluid extraction, ultrasound extraction, cold pressing method, fatty acids, stability of formulations Objavljeno v DKUM: 15.10.2025; Ogledov: 0; Prenosov: 10
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5. Znanost in umetnost na Univerzi v MariboruDean Korošak, Andreja Nekrep, Joso Vukman, Željko Knez, Dušica Pahor, Andraž Stožer, Polona Tominc, Gorazd Bajc, Oto Rimele, Tomaž Svete, 2025, samostojni znanstveni sestavek ali poglavje v monografski publikaciji Ključne besede: univerze Objavljeno v DKUM: 22.09.2025; Ogledov: 0; Prenosov: 6
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6. Functionalized micellar membranes from medicinal mushrooms as promising self-growing bioscaffoldsNika Kučuk, Mateja Primožič, Željko Knez, Maja Leitgeb, 2025, izvirni znanstveni članek Opis: Micellar or mycelial membranes from medicinal mushrooms are self-growing fibrous polymeric biocomposites that are biocompatible, biodegradable, cost-effective, and environmentally friendly. In this study, the cultivation process for the medicinal mushrooms Ganoderma lucidum and Pleurotus ostreatus has been optimized via submerged cultivation to maximize growth and promote the formation of micellar membranes with high water-absorption capacity. Optimal growth conditions were achieved at an alkaline pH in a medium containing malt extract for G. lucidum, while for P. ostreatus, these were in a glucose-enriched medium. The hydrophilic underside of the micellar membranes led to a high-water uptake capacity. These membranes exhibited a broad spectrum of functional groups, thermal stability with decomposition temperatures above 260 °C, and a fibrous and porous structure. The micellar membranes from both mushrooms were additionally functionalized with mango peel extract (MPE), resulting in a uniform and gradual release profile, which is an important novelty. They also showed successful antimicrobial activity against Escherichia coli and Staphylococcus aureus growth. MPE-functionalized micellar membranes are, therefore, innovative biocomposites suitable for various biomedical applications. As they mimic the extracellular matrix of the skin, they are a promising material for tissue engineering, wound healing, and advanced skin materials applications. Ključne besede: medicinal mushrooms, Ganoderma lucidum, Pleurotus ostreatus Objavljeno v DKUM: 04.09.2025; Ogledov: 0; Prenosov: 6
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7. Impact of storage conditions on stability of bioactive compounds and bioactivity of beetroot extract and encapsulatesVesna Postružnik, Slađana Stajčić, Dragana Borjan, Gordana ĆetkoviĆ, Željko Knez, Maša Knez Marevci, Jelena J. Vulić, 2025, izvirni znanstveni članek Opis: Background: In this study, bioactive compounds (phenolics and betalains) extracted from beetroot were stabilized by encapsulation with maltodextrin and soy protein by the freeze drying method. Stability of bioactive compounds and bioactivities in a beetroot extract and encapsulates during 60 days of storage at 4 ◦C (without light) and at 25 ◦C (with and without light) were investigated. (2) Methods: Contents of bioactive compounds and bioactivity (antioxidant activity by DPPH, RP, and ABTS tests; anti-inflammatory and antihyperglycemic activity) were determined. Improvement in stability of bioactives’ content and bioactivity of prepared encapsulates in relation to the extract was observed after storage at room temperature under light conditions. (3) Results: Encapsulation with maltodextrin showed improvement in stability of all studied bioactive parameters, while an encapsulate with soy protein improved stability of bioactives and antioxidant activity compared to the extract. The encapsulated beetroot extract represents a promising food additive for functional foods due to their content of bioactive compounds and consequent bioactivities. Ključne besede: isolation, phenolic copound, colorants, formulation, functional foods Objavljeno v DKUM: 08.08.2025; Ogledov: 0; Prenosov: 11
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8. Beneficial effects of castanea sativa wood extract on the human body and possible food and pharmaceutical applicationsTaja Žitek Makoter, Mojca Tancer Verboten, Ivan Mirt, Katarina Zupančić, Darija Cör Andrejč, Željko Knez, Maša Knez Marevci, 2024, pregledni znanstveni članek Opis: The aim of this review was to investigate the potential use of Castanea sativa wood extract
as a food supplement and to evaluate its beneficial properties for human health. The results of the
limited amount of studies suggest promising properties, including potential anti-inflammatory effects.
The literature indicates that the extract, which is rich in bioactive compounds such as tannins, offers
promising therapeutic possibilities for the treatment of conditions associated with chronic inflammation. Consequently, interest in its use in food and pharmaceuticals is growing. Phytochemical
studies have reported antioxidant and antimicrobial activities, and anti-inflammatory, anticancer,
hypolipidemic, hypoglycemic, and neuroprotective activities. A suitable extraction method and
solvent is crucial for the isolation of bioactive compounds, being green extraction technologies outstanding for the industrial recovery of chestnut wood’s bioactive compounds. Nevertheless, it is
important to emphasize the importance of adhering to regulatory guidelines and obtaining the necessary approvals from regulatory authorities to ensure product safety and compliance. The regulation
of herbal medicinal products with proven efficacy and traditional herbal medicinal products is well
defined, monitored by authorized bodies, and subject to strict control measures. It is noteworthy
that medicinal products are subject to stringent quality testing to ensure safety and efficacy in use,
whereas there are no comparable regulatory standards and specific labeling requirements for dietary
supplements. When using herbal products, compliance with established standards in health research
is essential. Ključne besede: Castanea sativa, wood extracts, tannins, antioxidat activity, anti-inflammatory activity, antimicrobial activity Objavljeno v DKUM: 30.07.2025; Ogledov: 0; Prenosov: 10
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9. Enhancing strength and ▫$CO_2$▫ uptake in lignite-based fly ash geopolymer mortar through supercritical carbonationTinkara Marija Podnar, Željko Knez, Gregor Kravanja, 2025, izvirni znanstveni članek Opis: This study demonstrates the potential of supercritical CO₂ curing to enhance the performance and sustainability of lignite-based fly ash geopolymer mortar offering a promising approach to reducing CO₂ emissions in the construction industry while improving material properties. The research comprehensively compared conventional curing (GEO-REF) with supercritical CO₂ curing (GEO-CO₂), revealing that GEO-CO₂ samples exhibited higher compressive and flexural strengths, achieving peak performance almost immediately after curing. Supercritical CO₂ exposure resulted in enhanced carbonation, with a depth of up to 7.6 mm and a carbonation rate of up to 67 %. XRD confirmed phase changes due to CO₂ curing, with GEO-CO₂ showing additional calcium carbonate-calcite, calcium carbonate-aragonite, and calcium silicate hydroxide compared to GEO-REF. Nitrogen adsorption/desorption studies indicated larger pore diameters but a reduced BET surface area in GEO-CO₂ samples, suggesting structural changes due to CO₂ exposure. TGA analysis revealed that supercritical CO₂ curing reduced water retention and enhanced carbonation, resulting in increased CaCO₃ content and changes in Ca(OH)₂ levels. Ključne besede: geopolymer, fly ash, carbonation, CO2 fixation, supercritical CO2, high pressure reactor Objavljeno v DKUM: 25.07.2025; Ogledov: 0; Prenosov: 4
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10. Synergistic effect of supercritical and ultrasound-assisted ginger (Zingiber officinale Roscoe) extractsTaja Žitek Makoter, Nika Kučuk, Vesna Postružnik, Maja Leitgeb, Željko Knez, Mateja Primožič, Maša Knez Marevci, 2022, izvirni znanstveni članek Opis: Proper processing of natural material is crucial to obtain an extract with high content of
biologically active components. Dried, grinded ginger roots were extracted by ultrasonic method
and supercritical extraction with CO2
. The aim of the study was to determine if a mixture of the two
types of extracts attained by different methods and solvents exhibits better bioavailability than each
extract itself. Therefore, both extracts were analytically evaluated and then mixed in a ratio of 1:1.
The supercritical extract (SCG extract) and the mixed extract (mixG extract) had high antioxidant
activity (78% and 73%) and total phenols (827 mg/g ext. and 1455 mg/g ext.), which is also consistent
with the levels of gingerol (303 mg/g ext. and 271 g/g ext.) and shogaol (111 mg/g ext. and 100 g/g
ext.) in the extracts. In comparison to both pure extracts higher levels of total phenols were found
in the extract mixG. This could be the reason for the significant inhibition of melanoma cells and
antimicrobial potential (against Staphylococcus aureus, Escherichia coli, and Candida albicans). The
combination of the extracts resulted in a significant increase in the inhibition of selected microbial
and melanoma cells WM-266-4 compared to the control. Cell viability decreased below 60% when
mixG extract was applied. Antimicrobial activity has been confirmed. Ključne besede: ginger, supercritical fluid extraction, ultrasound-assisted extraction, antimicrobial activity Objavljeno v DKUM: 09.05.2025; Ogledov: 0; Prenosov: 15
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