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Structure-property coupling in cracked iron oxide nanoparticles: Synthesis conditions, magnetic properties, MRI relaxivity and biocompatibility
No full textThis study reports a simple and environmentally friendly synthesis of hematite nanoparticles with tunable magnetic properties, including quasi-superparamagnetic behavior and a suppressed Morin transition. The hematite nanoparticles were synthesized via high-temperature hydrolysis of aqueous FeCl3, with synthesis durations of 3 h (sample S1) and 6 h (sample S2). XRD analyses confirmed the formation of phase-pure hematite, while TEM imaging revealed a distinctive cracked-spherical morphology with an average diameter of ≈ 35 nm and surface cracks 1–2 nm wide. The critical size for superparamagnetism and the suppression of the Morin transition below 150 K in hematite (α-Fe2O3) remain insufficiently studied. Magnetic properties revealed a size- and surface-dependent magnetic behavior. Sample S1 exhibited quasi-superparamagnetic behavior, characterized by a high blocking temperature (TB ≈ 275 K) and an irreversibility temperature exceeding room temperature (Tirr > 300 K). In contrast, sample S2 displayed a strongly suppressed Morin transition at TM ≈ 130 K. These results show that hematite nanoparticles ≈ 35 nm in size approach the superparamagnetic threshold. We attribute the modified magnetic response to enhanced surface disorder and strain associated with the cracked morphology, supported by XRD strain analysis (Williamson–Hall), HRTEM evidence of structural disorder and comparative discussion with non-cracked hematite. In addition to their tunable magnetic properties, the hematite nanoparticles demonstrated a promising potential for biomedical applications, exhibiting transverse and longitudinal MRI relaxivities (r2 ≈ 4.58 mM−1s−1 and r1 ≈ 0.075 mM−1s−1, respectively) and low cytotoxicity. This work highlights the importance of surface morphology and particle size in controlling the magnetic behavior of hematite nanostructures and their potential use as MRI contrast agents.Peer-reviewed manuscript available at: [https://vinar.vin.bg.ac.rs/handle/123456789/16117
Valorization of tomato stem waste: Lignin nanoparticles as eco-friendly platforms for 2,4-D and antimicrobial applications
No full textThis study explores the valorization of organosolv lignin extracted from tomato stems (tOL) and its transformation into tomato lignin nanoparticles (tLNP) via a hydrotropic synthesis method using sodium p-toluenesulfonate (p-TSA). The structural and chemical properties of tOL and tLNP were thoroughly characterized using SEM, FTIR, UV-Vis, DLS, Zeta potential, and NMR analyses, confirming successful nanoparticle formation with favorable physicochemical properties. Both tOL and tLNP exhibited strong antimicrobial activity, achieving maximum inhibition of Escherichia coli within 4 h of contact. Furthermore, tLNP were employed as carriers for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and tested in field trials, demonstrating effective herbicide delivery and enhanced performance under practical agricultural conditions. These results highlight the potential of tomato stem-derived lignin nanoparticles as multifunctional, sustainable materials for agrochemical applications, offering simultaneous waste valorization, antimicrobial protection, and environmentally friendly pesticide delivery
Stability of subsonic and supersonic solitons in DNA
No full textIn the present work, we rely on the helicoidal Peyrard-Bishop model of DNA and use a continuum approximation to solve a crucial dynamical equation of motion. This brings about kink solitary waves moving along the chain. We demonstrate that viscosity is crucial, as no waves are stable when viscosity is neglected. Furthermore, we show that, when viscosity is taken into consideration, the subsonic kink solitons are stable, while the supersonic ones are not.This is the peer-reviewed version of the article: Ranković, D., Prekrat, D., Batova, A., & Zdravković, S. (2026). Stability of subsonic and supersonic solitons in DNA. Chaos: An Interdisciplinary Journal of Nonlinear Science, 36(1). [http://dx.doi.org/10.1063/5.0277901
Magnetically Recoverable ICT-Functionalized Fe3O4 Nanoparticles for Efficient Horseradish Peroxidase Immobilization
No full textThe formation of interfacial charge transfer (ICT) complexes between phenolic ligands and metal oxide surfaces enables surface functionalization strategies with potential applications in catalysis and bioconjugation. In this study, magnetite (Fe3O4) nanoparticles were modified with two phenolic ligands, 5-aminosalicylic acid (5ASA) and caffeic acid (CA), to generate ICT complexes capable of covalent or non-covalent enzyme immobilization, respectively. The modified nanomaterials were structurally characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Horseradish peroxidase (HRP) was immobilized on these functionalized supports using varying nanoparticle amounts (10-30 mg) and initial enzyme concentrations (25-250 µg mL-1). Catalytic activity was evaluated using pyrogallol oxidation assays. The Fe3O4/5ASA-HRP system exhibited a maximum activity of 2.5 U per 20 mg of support (approximately 125 U g-1), whereas Fe3O4/CA showed minimal activity under the same conditions. Enzyme loading studies confirmed that 5ASA-enabled covalent attachment resulted in significantly higher immobilization efficiency (up to 1068 mg g-1) compared to the CA system. Reusability tests demonstrated that the Fe3O4/5ASA system retained high absolute catalytic activity during the initial reaction cycles and consistently outperformed the non-covalently immobilized Fe3O4/CA system upon repeated reuse. The magnetic properties of Fe3O4 allowed rapid recovery of the biocatalysts using an external magnetic field. These results highlight the effectiveness of ICT-based functionalization for enzyme immobilization, positioning Fe3O4/5ASA as a promising platform for robust and reusable biocatalysts in environmental and industrial applications
Metol Electrochemical Sensing over LASIS Gold Nanoparticle-Modified Screen-Printed Carbon Electrodes in Adsorption Studies with Waste Biomass-Derived Highly Porous Carbon Material
No full textThis work used activated carbon material obtained by chemical activation of abundantly available agricultural sunflower waste residues to remove metol (4-(methylamino) phenol sulfate, MTL) from aqueous solutions. The adsorbent structure was characterized using SEM-EDS and FT-IR spectroscopy. A modified screen-printed carbon electrode (SPCE) with gold nanoparticles synthesized using the Laser Ablation Synthesis in Solution (LASIS) method was used to detect MTL. The successful LASIS formation of gold nanoparticles was confirmed by the specific dark burgundy–red color. TEM measurements showed uniform pseudo-spherical particles with an average diameter of 7.9 ± 0.2 nm. The modified electrode showed improved electrochemical activity, which was confirmed by comparing it with an unmodified electrode using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was subsequently used to optimize the MTL detection conditions. UV–Vis spectroscopy was used to optimize the adsorption conditions, with the optimal values for pH and contact time found to be 8 and 120 min, respectively. The electrochemical detection of MTL was performed using differential pulse voltammetry, and the linear calibration range was established for concentrations ranging from 0.73–49.35 µM. The obtained limits of detection (LOD) and quantification (LOQ) were 0.06 µM and 0.2 µM, respectively. The efficiency of MTL removal was 100% after a contact time of 1 min and remained at 100% after 120 min
Poster: Efficient One-Step Extraction and Micellization of Parthenolide From Biomass Using Aqueous Biphasic Systems
No full textINTRODUCTION Feverfew (Tanacetum parthenium (L.) Sch. Bip.) is a well-known medicinal plant valued for its bioactive compound parthenolide (PAR), a sesquiterpene lactone with demonstrated anti-inflammatory, anticancer, and neuroprotective properties. However, the limited availability and high production cost of PAR remain major obstacles to its broader therapeutic application. Traditional extraction methods often rely on toxic organic solvents such as methanol or acetonitrile, raising environmental and safety concerns. There is a need for greener, safer, and more economical extraction methods that also preserve the potential synergies of PAR with other native bioactives. In this work, we propose a sustainable, solvent-free, one-step extraction and micellization process using thermoresponsive aqueous biphasic systems (ABS) composed of Pluronic 17R4 polymer and choline-based ionic liquids (ChILs). This novel approach simultaneously extracts and encapsulates PAR, offering a streamlined route for drug delivery applications while reducing environmental impact. EXPERIMENTAL METHODS Dried feverfew biomass was mixed with a pre-optimized ABS system composed of Pluronic 17R4, ChILs, and water at a ratio of 1:50 (biomass to solvent). Samples were gently mixed at 25 °C for 2 hours to maintain a homogeneous single-phase system, followed by centrifugation (5 minutes at 5000 rpm) to remove solid residues. Further phase separation was induced by a second centrifugation step at 35 °C. The resulting IL-rich and Pluronic-rich phases were collected, diluted, and analyzed by HPLC to quantify PAR yield, expressed as mg of PAR per g of dried biomass. Micelle formation in the Pluronic-rich phase was characterized via Dynamic Light Scattering (DLS). RESULTS AND DISCUSSION Key extraction parameters were optimized, including ABS composition, biomass-to-solvent ratio, and mixing conditions. The highest extraction yield of 2.52 mg PAR/g biomass was achieved with an ABS consisting of 25% Pluronic 17R4, 7% ChIL (choline lactate), and 68% water, using mild shaking at 100 rpm. Notably, micellization occurred concurrently with extraction, forming nanostructured micelles in the Pluronic-rich phase. DLS analysis revealed micelle sizes ranging from 113 to 187 nm, depending on the specific ChIL used. These results demonstrate the dual functionality of the developed ABS: efficient extraction of parthenolide and its in-situ micellization, which may enhance its bioavailability and delivery potential. Moreover, this method eliminates the need for harmful solvents, offering an environmentally responsible and scalable alternative for pharmaceutical-grade PAR production.Poster presented at: 23rd International Symposium on Microencapsulation, 10-12 September 2025, Ferrara, Italy.Abstract: [https://vinar.vin.bg.ac.rs/handle/123456789/16062
Sustainable technology for production of lignocellulosic membranes for removal of anionic and cationic pollutants from water
No full textOva doktorska disertacija bavi se održivim tehnologijama za proizvodnju lignoceluloznihmembrana namenjenih uklanjanju anjonskih i katjonskih zagađivača iz vode u cilju očuvanja životnesredine i poboljšanju kvaliteta života. Ispitivane su dve vrste funkcionalizovanih membranana na baziceluloze. Prva membrana (TOPM) je dobijena je iz pamučnih lintersa oskidisanih sa 2,2,6,6-tetrametilpiperidin-1-oksil radikalom. Druga membrana je dobijena (HHH-UKM) katjonskomfunkcionalizaijom otpadnih vlakana konoplje. Svi materijali su okaraketrisani primenomspektroskopskih, mikroskopskih i analitičkih tehnika. Adsorpciona svojstva membrana ispitana su ušaržnom i protočnom sistemu. Primenjene adsorpcione izoterme, opisale su interakciju između adsorbatai adsorbenta u ravnotežnom stanju ispitivanog sistema i potvrdile visoke adsorpcione kapacitetemembrana za uklanjanje katjonskih i anjonskih zagađivača. Nakon višeciklične desorpcije, obemembrane su podvrgnute testovima biorazgradivosti. Dobijeni rezultati (70 dana za TOPM i 60 dana zaHHH-UKM) potvrdili su cikličnost razvijene tehnologije sa implementiranim principima održivosti.Nakon desorpcije, boje su podvrgnute fotokatalitičkoj degradaciji ili enzimskoj dekolorizaciji, dok suPb2+, As(V) i Cr(VI) tretirani precipitacijom, radi smanjenja negativnog ekološkog uticaja. StabilizacijaPb2+ izvedena je u obliku olovo-ftalata, koji je korišćen kao punilac za kompozite na bazi nezasićenepoliestarske smole (NPSM). Ovi kompoziti su obogaćeni akrilno modifikovanim kraft ligninom (A-KL),čime su postignuta poboljšana mehanička i vatrootporna svojstva materijala.Rezultati sugerišu na visok afinitet membrana prema zagađivačima, bezbednosti životne sredinei održivosti jer su proizvedene od obnovljivih i otpadnih materijala.This doctoral dissertation focuses on sustainable technologies for producing lignocellulosicmembranes designed to remove anionic and cationic pollutants from water, with the goal of protectingthe environment and enhancing the quality of life. Two types of functionalized cellulose-basedmembranes were investigated. The first membrane (TOPM) was obtained from cotton linters oxidizedwith 2,2,6,6-tetramethylpiperidin-1-oxyl radical. The second membrane (HHH-UKM) was developedthrough the cationic functionalization of waste hemp fibers. All materials were characterized usingspectroscopic, microscopic, and analytical techniques. The adsorption properties of the membranes werestudied in both batch and flow systems. The applied adsorption isotherms described the interactionbetween adsorbate and adsorbent at equilibrium, confirming the high adsorption capacities of themembranes for removing cationic and anionic pollutants. After multiple desorption cycles, bothmembranes were subjected to biodegradability tests. The results (70 days for TOPM and 60 days forHHH-UKM) confirmed the cyclic nature of the developed technology, aligned with sustainabilityprinciples. After desorption, the dyes underwent photocatalytic degradation or enzymatic decolorization,while Pb2+, As(V), and Cr(VI) were treated through precipitation to mitigate their environmental impact.Pb2+ was stabilized in the form of lead-phthalate, which was used as a filler for composites based onunsaturated polyester resin (NPSM). These composites were enriched with acrylate-modified kraftlignin (A-KL), resulting in improved mechanical and fire-resistant properties.The results indicate a strong affinity of the membranes for pollutants, as well as environmentalsafety and sustainability, given that they were produced from renewable and waste materials
Ash melting temperatures for biomass fuels: Effect of fuel sample preparation by ashing at different temperatures
No full textIn the discussion on biomass as a renewable energy source, its benefits are repeatedly recognised: - reducing greenhouse gas emissions by substituting fossil fuels; - increasing energy security by diversifying the energy mix and reducing dependence on imported fuels; - creating economic prospects by promoting rural development, job creation and valorisation of waste streams. However, the utilisation of biomass in combustion processes faces some challenges. This article emphasises one of them: the ash problem due to the pronounced tendency to form deposits on the heating surfaces. In order to properly design or select a biomass combustion system, the indicators of the tendency of biomass ash to form deposits on the heating surfaces must be adequately determined. Determining ash melting temperatures for biomass is crucial for understanding combustion behaviour and potential problems such as slagging and fouling. Biomass ash melting temperatures are typically determined at 550 °C for biofuels and 815 °C for solid mineral fuels. Some established certification schemes and national regulations favour the preparation of biomass samples by ashing at 815 °C. In this paper, the question is answered whether and how the ashing temperature of the biomass sample influences the characteristic points of the ash melting temperatures. The characteristic ash melting temperatures were determined for different types of biomass (wood chips, soybean and maize straw), where the ash sample was obtained by ashing at three different temperatures (550, 710 and 815 °C).ISAE : The 7th International Symposium on Agricultural Engineering : 6-8 October, Belgrade
Green Extraction of Bioactives from Curcuma longa Using Natural Deep Eutectic Solvents: Unlocking Antioxidative, Antimicrobial, Antidiabetic, and Skin Depigmentation Potentials
No full textThis study evaluates the efficiency of 20 Natural Deep Eutectic Solvents (NADES) formulations for extracting curcuminoids and other bioactive compounds from turmeric and emphasize their ability to preserve and enhance antioxidant, antimicrobial, antidiabetic, and skin depigmentation effects. The NADES formulations, prepared using choline chloride (ChCl) combined with sugars, carboxylic acids, glycerol, amino acids, urea, polyols, and betaine, were assessed for their extraction efficiency based on the total phenolic content and curcumin concentration. Fourier transform infrared spectroscopy was employed to characterize the synthesized NADES and confirm their chemical composition. Bioactivity evaluations included antioxidant assays (ABTS and DPPH), antidiabetic tests (α-amylase inhibition), antimicrobial assays, and skin depigmentation (tyrosinase inhibition). The results demonstrated that NADES significantly enhanced the extraction efficiency and bioactive properties of turmeric extracts compared to water as a conventional green solvent. NADES 18 (ChCl/1,2-propanediol/water 1:1:1) and NADES 19 (glycerol/betaine/water 1:1:3) exhibited the highest extraction yields, with curcumin concentrations of 30.73 ± 1.96 mg/g and 31.70 ± 2.02 mg/g, respectively, outperforming water (26.91 ± 1.72 mg/g), while NADES 17 (ChCl/1,2-propanediol/water 0.5:3:0.5:5) and NADES 20 (glycerol/lysine/water 1:1:3) exhibited the most potent antioxidant activity. Furthermore, NADES 14 (ChCl/lactic acid/water 1:2:5) demonstrated the strongest tyrosinase inhibition (98.7%), supporting its potential for skin-brightening applications, including notable α-amylase inhibition exceeding 90%. This study aligns with the principles of green chemistry, as NADES are effective and sustainable solvents for natural product extraction. The presenting benefits of improved extraction efficiency and enhanced bioactivities position NADES as a promising and eco-friendly approach for developing efficient bioactive compound extraction methodologies. © 2025 by the authors
Physicochemical and biological properties of bioactive calcium aluminate dental cement enriched with zirconium dioxide
No full textThis study aimed to investigate the physicochemical and biological properties of newly synthesized calcium aluminate cement (CAC) enriched with ZrO2. Two experimental mixtures were tested: CAC with added 20 wt% of ZrO2 (ECCA + ZrO2) and pure CAC. Mineral trioxide aggregate (MTA) and Portland cement served as controls. The following physicochemical characteristics were examined: radiopacity, setting time, compressive strength, elemental and phase composition, and surface morphology. For biological testing, materials were implanted in subcutaneous rat tissue, and their effect was evaluated at 7, 30, and 90 days post-implantation. Although both ECCA + ZrO2 and MTA satisfied the ISO standard (>3 mm Al), MTA exposed the highest radiopacity compared to other materials (p < 0.05). The ECCA + ZrO2 recorded the lowest initial and final setting time (p < 0.05) and exhibited the highest compressive strength among tested cements (p < 0.05). All materials induced minimal inflammation and tissue changes; however, ECCA + ZrO2 showed a slight advantage after 90 days. Experimental CAC demonstrated satisfactory physicochemical and biological properties. With superior compressive strength, shorter setting time, and high biocompatibility, the novel ECCA + ZrO2 mixture shows promise for future clinical application. © 2025 Elsevier Ltd and Techna Group S.r.l