1. New approach for adsorptive removal of the antibiotic ciprofloxacin: carboxymethyl-dextran-functionalised magnetic iron oxide nanomaterialsErik Mihelič, Lidija Fras Zemljič, Marjana Simonič, Sašo Gyergyek, Alenka Vesel, Silvo Hribernik, Matej Bračič, Ivan Anžel, Olivija Plohl, 2025, original scientific article Abstract: Antibiotic residues in environmental media pose a significant health, social and economic problem and require effective removal strategies. This study presents a novel approach for the removal of the antibiotic ciprofloxacin from water sources using magnetic iron oxide nanoparticles (MNPs) synthesised by co-precipitation, and subsequently functionalised with the polysaccharide carboxymethyl-dextran (CMD). The prepared nanoadsorbent was characterised extensively by various physicochemical analyses, to evaluate its morphology, crystal structure, surface chemistry, electrokinetic properties, thermogravimetric properties and magnetic features. These analyses confirmed the successful functionalisation of the MNPs with CMD highlighting its potential for effective adsorption applications. The stability of CMD coating on MNPs was evaluated in terms of total carbon content, an important, yet often overlooked factor. The adsorption performance of MNPs@CMD for ciprofloxacin was investigated systematically by studying the effects of adsorbent dosage, pH, initial ciprofloxacin concentration, ionic strength, adsorption time and kinetics, temperature, and reusability. Under optimal conditions, nanoadsorbent exhibited a satisfactory maximum adsorption capacity of 14.71 mg/g, and maintained a removal eff iciency of 79 % after four cycles, with minimal desorption of CMD layer on the MNPs. These findings demonstrate the potential of this magnetic polysaccharide nanoadsorbent for effective removal of ciprofloxacin from aqueous environments, enabling magnetic recovery and reuse. Keywords: Carboxymethyl-dextran-MNPs, ciprofloxacin, adsorption Published in DKUM: 26.05.2025; Views: 0; Downloads: 6
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2. The effect of preconditioning strategies on the adsorption of model proteins onto screen-printed carbon electrodesTea Romih, Ivan Konjević, Lea Žibret, Ika Fazarinc, Ajda Beltram, David Majer, Matjaž Finšgar, Samo B. Hočevar, 2022, original scientific article Abstract: The preconditioning and modification of the supporting electrode surface is an essential
step in every biosensor architecture. In particular, when using screen-printed carbon electrodes (SPEs)
as inexpensive and convenient disposable sensor substrates, their somewhat lower electrochemical
(surface) reproducibility might represent a complex hurdle. Herein, we investigated the effect of
selected preconditioning strategies, such as cyclic voltammetric pretreatment, in H2SO4 and H2O2
and plasma pretreatment with a positive and negative glow discharge, which all improved the electrochemical stability of the unmodified SPEs. Furthermore, we studied the influence of preconditioning
strategies on the adsorption kinetics of the two most commonly used building blocks for biosensor
preparation, i.e., bovine serum albumin (BSA) and protein A. We observed an advantageous effect
of all the examined preconditioning strategies for the modification of SPEs with protein A, being
the most effective the negative glow discharge. On the other hand, BSA exhibited a more complex
adsorption behavior, with the negative glow discharge as the only generally beneficial preconditioning strategy providing the highest electrochemical stability. Protein A revealed a more substantial
impact on the electrochemical signal attenuation than BSA considering their same concentrations in
the modification solutions. For both BSA and protein A, we showed that the concentrations of 5 and
10 µg mL−1 already suffice for an electrochemically satisfactorily stable electrode surface after 60 min
of incubation time, except for BSA at the positive-plasma-treated electrode. Keywords: screen-printed carbon electrode, SPE, electrochemical biosensor, adsorption, bovine serum albumin, protein A, glow discharge Published in DKUM: 15.05.2025; Views: 0; Downloads: 0
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3. Adsorption of pollutants from colored wastewaters after natural wool dyeingAlenka Ojstršek, Primož Vouk, Darinka Fakin, 2022, original scientific article Abstract: The presented study assesses the efficiency of selected adsorbents, zeolite 4A in two
particle sizes and pelletized activated carbon (AC), for the potential removal of color, chemical
oxygen demand (COD), total organic carbon (TOC) and metals from wastewaters after natural wool
dyeing. Firstly, the natural coloring compounds were extracted from dried common walnut (Juglans
regia) leaves and used further for exhaustion dyeing of wool fibers, together with three different
metallic salts in two concentrations (meta-mordanting). Effluents with higher mordant concentration
were additionally treated according to a shake-flask adsorption experiment. The obtained results
revealed efficient removal of exceeded metallic ions by zeolite (up to 94.7%), on account of their
superior ion exchange capability as compared to AC. The zeolites also reduced turbidity and electrical
conductivity significantly. On the other hand, AC was more efficient for the reduction in organic
pollution, COD up to 96% and TOC up to 95%, due to its higher specific surface area and total pore
volume, and, thus, higher potential for adsorption of different compounds in comparison to 4A.
All three proposed adsorbents lowered wastewaters’ coloration remarkably, up to 78% (AC) and up
to 71% (4A), depending on the type of effluent/mordant and inspected wavelength; although, the
spectral absorbance coefficient (SAC) values remained highly above the limit values for discharge of
wastewaters into watercourses. Keywords: wool dyeing, natural dyes, wastewater treatment, decoloration, heavy metals’ reduction, adsorption Published in DKUM: 20.03.2025; Views: 0; Downloads: 4
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4. Cu(II) and Ni(II) adsorption on torrefied wood waste biomassMarjana Simonič, Darko Goričanec, Aleksandra Petrovič, Ilda Silić, Danijela Urbancl, 2025, original scientific article Abstract: The aim of the research was to study the torrefaction processes of wood biomass, compare the product characteristics at different torrefaction temperatures, and assess both moisture adsorption on raw and torrefied samples, as well as metal (Cu(II) and Ni(II)) adsorption on torrefied biomass. The novelty of the research was to investigate whether the presence of adsorbed metals in torrefied biomass significantly affects the energetic properties of the torrefied biomass, compared to torrefied biomass without metals. First, wood samples were torrefied at temperatures of 250 °C, 350 °C, and 400 °C. Following torrefaction, thermogravimetric analysis (TGA) was performed to evaluate mass loss and thermal stability. Next, changes in surface functional groups were examined, and higher heating values (HHV) were measured to assess the energy content. The results showed that torrefaction significantly increased the hydrophobicity of the biomass, leading to reduced moisture adsorption and enhanced material properties. Additionally, the adsorption of Cu(II) and Ni(II) ions on torrefied biomass was investigated. The results showed that the adsorption efficiency for Cu(II) was higher, reaching 62.4%, compared to Ni(II) at 21.2%. The adsorption process followed a pseudo-second-order kinetic model, which indicated that chemisorption was the dominant mechanism. Keywords: adsorption, torrefication, nitrogen atmosphere, metals Published in DKUM: 12.03.2025; Views: 0; Downloads: 6
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5. Composite materials based on waste chicken feather fibers for oil-spill managementSimona Strnad, Andraž Jug, Zdenka Peršin Fratnik, 2024, original scientific article Abstract: Oil spills remain one of the greatest man-made ecological threats, despite numerous advanced cleanup approaches. They still pose a major challenge in the search for materials and technologies that work as efficiently and sustainably as possible. Promising natural materials include poultry feathers, which are produced in large quantities every day as a byproduct of the meat industry. In this study, the influence of different forms of absorbents (loose feathers, pillows, and sheets) based on chicken feathers and the addition of an inorganic absorbent, sepiolite, on their absorption capacity was investigated. The chemical and physical surface properties, like morphology, chemical composition, zeta potential, surface free energies and oil absorption capacities were analyzed. The Gibbs free energy of immersion wetting with oil and the work of adhesion of the adsorbents, calculated based on contact angle measurements, were confirmed by the tests of adsorption capacities according to the ASTM 726–12 standard. The results showed that pure loose feathers have the highest oil adsorption capacity, while feather pillows have only half, and composite sheets have only a quarter of this capacity. The addition of inorganic adsorbent sepiolite did not increase the absorption capacity of the composites. Keywords: chicken feather fibers, composites, sepiolite, surface properties, oil adsorption, oil-spill management Published in DKUM: 10.05.2024; Views: 183; Downloads: 27
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6. Utilisation of renewable electricity to produce synthetic methaneKlemen Rola, Sven Gruber, Danijela Urbancl, Darko Goričanec, 2023, original scientific article Keywords: power-to-methane, P2M, synthetic methane, CO2 methanation, Aspen Plus, Aspen Adsorption Published in DKUM: 18.04.2024; Views: 203; Downloads: 13
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7. Bioactive functional nanolayers of chitosan-lysine surfactant with single- and mixed-protein-repellent and antibiofilm properties for medical implantsUrban Ajdnik, Lidija Fras Zemljič, Olivija Plohl, Lourdes Pérez, Janja Trček, Matej Bračič, Tamilselvan Mohan, 2021, original scientific article Abstract: Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption arethe prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer apromising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to researchand develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties incontact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-freepolyelectrolyte−surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionicsurfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria.We successfully introduced the PESC as bioactive functional nanolayers on the“model”and“real”polydimethylsiloxane (PDMS)surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly depositednanolayers (thickness: 44−61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serumalbumin,fibrinogen, andγ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartzcrystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ:−19 to−30mV at pH 7.4), water content (1628−1810 ng cm−2), and hydration (low viscosity and elastic shear modulus) correlated with themass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed thatthe charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcusaureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatingswith simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leadingto a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents). Keywords: silicone implants, protein-repellent, antimicrobial, chitosan, lysine, bioactive coatings, adsorption, QCM-D Published in DKUM: 15.04.2024; Views: 266; Downloads: 21
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8. Active cellulose acetate/chitosan composite films prepared using solution blow spinning: structure and electrokinetic propertiesAna Kramar, Thomas Luxbacher, Nasrin Moshfeghi Far, Javier González-Benito, 2023, original scientific article Keywords: cellulose acetate, chitosan, solution blow spinning, protein adsorption, food packaging Published in DKUM: 10.04.2024; Views: 251; Downloads: 19
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9. Cellulose nanofibrils-reinforced pectin membranes for the adsorption of cationic dyes from a model solutionAlenka Ojstršek, Selestina Gorgieva, 2024, original scientific article Abstract: In the presented research, a facile, one-step method for the fabrication of cellulose nanofibrils/pectin (CNFs/PC) membranes is described, which were tested further for their ability to remove cationic dyes from the prepared model solutions. For this purpose, ten membranes were prepared with different quantities of CNFs and PC with/without citric acid (CA) or CaCl2 as mediated crosslinking agents, and they were characterised comprehensively in terms of their physical, chemical, and hydrophilic properties. All the prepared CNFs/PC membranes were hydrophilic with a Water Contact Angle (WCA) from 51.23◦ (without crosslinker) up to 78.30◦ (CaCl2 ) and swelling of up to 485% (without crosslinker), up to 437% (CaCl2 ) and up to 270% (CA). The stability of membranes was decreased with the increase in PC; thus, only four membranes (M1, M2, M3 and M5) were stable enough in water after 24 h, and these were additionally applied in the adsorption trials, using two structurally different cationic dyes, i.e., C.I. Basic Yellow 28 (BY28) and C.I. Basic Blue 22 (BB22), in four concentrations. The highest total surface charge of M3 (2.83 mmol/g) as compared to the other membranes influenced the maximal removal efficiency of both dyes, up to 37% (BY28) and up to 71% (BB22), depending on the initial dye concentration. The final characteristics of the membranes and, consequently, the dye’s absorption ability could be tuned easily by changing the ratio between the CNFs and PC, as well as the type and amount of crosslinker. Keywords: cellulose nanofibrils, pectin, cationic dyes, adsorption, dye removal Published in DKUM: 12.03.2024; Views: 320; Downloads: 32
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10. Polyvinylpyrrolidone-stabilised gold nanoparticle coatings inhibit blood protein adsorptionHanuma Reddy Tiyyagura, Matej Bračič, Rebeka Rudolf, 2024, original scientific article Abstract: In this work, the ability of polyvinylpyrrolidone (PVP)-stabilised gold nanoparticle (AuNP) coatings to inhibit blood protein adsorption was evaluated by studying timeresolved solid–liquid interactions of the coatings with the model blood protein bovine serum albumin (BSA). Inhibiting unspecific blood protein adsorption is of crucial importance for blood-contacting implant devices, e.g. vascular grafts, stents, artificial joints, and others, as a preventive strategy for bacterial biofilm formation. A quartz crystal microbalance was used in this work to coat the AuNPs on piezoelectric sensors and to follow time-resolved solid–liquid interactions with the proteins. The AuNP coatings were evaluated for their wettability by contact angle measurements, their surface morphology by lightand atomic force microscopy, and their chemical composition by energy-dispersive X-ray spectroscopy. Results revealed a homogeneous distribution of AuNPs on the sensor surface with a dry mass coverage of 3.37 ± 1.46 µg/cm2 and a contact angle of 25.2 ± 1.1°. Solid–liquid interaction studies by quartz crystal microbalance showed a high repellence of BSA from the PVP-stabilised AuNP coatings and the importance of the PVP in the mechanism of repellence. Furthermore, the conformation of the polymer on the coatings as well as its viscoelastic properties were revealed. Finally, the activated partial thrombin time test and fibrinogen adsorption studies revealed that the AuNPs do not accelerate blood coagulation and can partially inhibit the adhesion of fibrinogen, which is a crucial factor in the common blood coagulation cascade. Such AuNPs have the potential to be used in blood-contact medical applications. Keywords: gold nanoparticles, ultrasonic spray pyrolysis, haemocompatibility, protein adsorption, quartz crystal microbalance Published in DKUM: 30.01.2024; Views: 377; Downloads: 35
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