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Magnetic immobilized laccase drives oxidative coupling for simultaneous removal and detoxification of flotation reagent 1-nitroso-2-naphthol in mineral processing wastewater
No full textMining sustainability requires cost-effective and eco-friendly technologies to mitigate residual organic flotation reagents in mineral processing wastewater (MPW). Despite its proven capacity to degrade recalcitrant contaminants, fungal laccase-mediated biotransformation of organic flotation reagents remains underexplored. Herein, a magnetic immobilized Trametes versicolor laccase (MITvLac) was evaluated as a potential alternative for the removal and detoxification of a typical mineral flotation reagent 1-nitroso-2-naphthol (1N2N). It was found that MITvLac was capable of transforming 1N2N over a broad pH range. The generated various homo/hetero-coupling oligomers/polymers upon oxidation of the target substrates were demonstrated by high-resolution mass spectrometry (HRMS), and the MITvLac-mediated 1N2N oxidative coupling mechanisms were elucidated. Additionally, the Vibrio fischeri bioluminescence inhibition assay and total organic carbon (TOC) analysis corroborated that the 1N2N transformation was accompanied by detoxification and a reduction in TOC of the reaction solution, the extent of which correlated with the extent of oxidation and polymerization. Moreover, MITvLac could be easily recovered and reused, while keeping its high removal efficiency of 1N2N in the actual MPW matrices. These findings underscore the potential of fungal laccase as an efficient alternative for remediation of organic flotation reagents-contaminated MPW
From Structure to Function: Zn/Mn-Modified Maghemite as an Advanced Nanoplatform for Magnetic Hyperthermia and Radionuclide Therapy
No full textThe development of nanoplatforms capable of efficient heat generation and stable radionuclide delivery is essential for effective bimodal cancer therapy. In this study, binary (Fe–M) and ternary (Fe–M–M′) metal oxide nanoparticles were synthesized via a polyol method optimized to produce flower-like γ-Fe2O3 (maghemite) structures, with M and M′ representing Zn and/or Mn. Comprehensive structural and magnetic characterization was conducted to explain the relationship between composition, defect structure, and hyperthermic performance. The analyses revealed that cation substitution induced an Fe-site vacancy, primarily at octahedral positions, leading to local structural distortions, as confirmed by powder X-ray diffraction and pair distribution function analysis. The optimized composition, with Zn/Mn/Fe = 0.040:0.182:1, exhibited the highest concentration of vacancies and structural disorder. These vacancies altered the bonding environment, enhancing magnetic interactions at tetrahedral sites while weakening those at the octahedral positions. The resulting multicore nanoflowers (20–63 nm; core size 13–18 nm) displayed strong heating performance, with intrinsic loss power ranging from 0.34 to 5.77 nHm2 kg–1. The optimized sample achieved a temperature increase of 30 °C within 2 min and a specific absorption rate of 369 W g–1. This composition was further coated with citrate (CA) and successfully radiolabeled with 177Lu, achieving a radiolabeling yield of 92.7% and excellent stability, thus forming a robust nanoplatform for combined magnetic hyperthermia and radionuclide therapy. Biological evaluation of the optimized S5 composition revealed selective cytotoxicity toward HeLa and LS174 cells, while toxicity was significantly lower to A549, A375, and normal MRC-5 cells. Citrate coating of S5 nanoparticles (S5@CA) drastically reduced their cytotoxicity across all tested cell lines (IC50 > 200 μg mL–1), confirming their enhanced biocompatibility for therapeutic applications. In HeLa cells subjected to magnetic hyperthermia, the viability decreased to approximately 84% after 30 min and 61% after 60 min of treatment, demonstrating the sustained hyperthermic effect at a controlled working temperature of 48 °C. These results underscore the effectiveness of cation substitution and vacancy engineering in tailoring the functional properties of maghemite-based nanomaterials for advanced multimodal cancer therapies
Si/Pyrex glass and poly(dimethylsiloxane)-based microfluidic devices with integrated heating elements for TiO2 nanoparticle synthesis
No full textThis paper presents two microreactors used to synthesize titanium(IV) oxide (TiO2) nanoparticles. The microreactors under investigation incorporate integrated heaters and possess distinct microchannel dimensions. The first microreactor comprises silicon and Pyrex glass, with its integrated heater produced through p-type diffusion. Conversely, the second microreactor is constructed from polydimethylsiloxane (PDMS) and features a wire-based integrated heater. Recognizing the significance of temperature control in the synthesis process, both experimental and simulation results pertaining to the behavior of the microreactor heaters are provided. The synthesis of TiO2 nanoparticles serves as a means to validate the efficacy of the microreactors. Comparative analysis reveals that the PDMS microreactor exhibits superior functionality when compared to the silicon/Pyrex glass counterpart. It has been demonstrated that upon a reaction time of 2 min within the microreactors, amorphous nanoparticles are formed, accompanied by partially developed crystallites corresponding to the anatase and rutile phases. Subsequent heating facilitates the complete conversion of the amorphous phase into the anatase phase. The utilization of a PDMS microreactor exhibits a heightened suitability for the synthesis of TiO2 nanoparticles with good photocatalytic efficiency, achieving 93.59 % methylene blue (MB) degradation after 90 min. This suitability arises from several key factors: enhanced production speed, the cost-effectiveness inherent in the material, and the prevention of channel blockage attributed to calcification during the reaction process
Enhanced photostability of naproxen through complexation with amino-modified beta-cyclodextrin
No full textCyclodextrins, cyclic oligomers containing 6-8 glucose units, are frequently used as complexing agents for a broad group of active pharmaceutical ingredients (APIs) in the pharmaceutical industry. Their use as enhancers of APIs solubility, as well as formulation stabilizers, photoprotectors and antioxidants, makes them an integral part of drug formulation development [1]. β-Cyclodextrins (β-CDs, 7 glucose units) are widely used for the aforementioned purposes, but they have limited water solubility and form low-stability complexes with APIs. To enhance the solubility and complexation potential of β-CD, 1,2-ethylenediamine (EDA) was used to synthesize amino-modified β-CD [2]. In this study, modified β-cyclodextrin was applied to improve the photostability of naproxen, a non-steroidal anti-inflammatory drug. The obtained results suggest that upon irradiation with a 254 nm UV lamp, complexes of naproxen with EDA-β-CD are more stable than with unmodified β-CD. Photodegradation was followed using reversed phase (C18) HPLC with PDA detection. Determined photodegradation constants (according to zero-order kinetics) were 2.13 × 10−6 mol/L×min for unmodified β-CD and 1.98 × 10−6 mol/L×min for EDA-β-CD. Degradation half times at 1.0 × 10-3 mol/L β-CD concentrations were 42.46 ± 2.68 min for unmodified β-CD and 45.01 ± 2.93 min for EDA-β-CD.
References
1. S. L. Yang, L. J. Zhao, S. M. Chi, J. J. Du, Q. Ruan, P. L. Xiao, Y. Zhao, J. Mol. Struct. 2019, 1183, 118-125.
2. J. M. Choi, K. Park, B. Lee, D. Jeong, S. D. Dindulkar, Y. Choi, E. Cho, S. Park, J. H. Yu, S. Jung, Carbohydr. Polym. 2017, 163, 118-128
Comparative experimental and DFT study of the electrochemical oxidation of azo pyridone dyes
No full textThis study examines electrooxidation behavior of three aryl azo pyridone using cyclic (CV) and square-wave voltammetry (SWV) on a glassy carbon electrode (GC) in Britton–Robinson (BR) aqueous buffer solutions and quantum-chemical calculations. Results indicate that the electrochemical activity is closely related to the presence of the hydrazone (–NH–N=) bridge of the dyes. The most stable protonated and deprotonated forms of dyes are identified by comparing experimental UV–Vis spectra with calculated spectra. Additionally, calculated ionization energies for both forms aligned with observed electrochemical activity, emphasizing the deprotonated
anionic form as the most active. The proposed electrooxidation mechanism suggests that initial step involves dye deprotonation to achieve the most stable anionic form, followed by electron removal to generate a radical, and subsequent geometric adjustments to optimize electron density distribution and stability. The differences of the electrochemical behavior of dyes are discussed with consideration of underlying mechanism
Квантнохемијско проучавање C–H···O интеракција између HTcO₄ и ароматичних аминокиселина
No full textThis study investigates C–H···O interactions between HTcO₄ and aromatic amino acids (phenylalanine, tyrosine, and tryptophan) through quantum-chemical calculations. The interaction energies calculations were combined with the analysis of Molecular Electrostatic Potentials (MEP) to understand the nature of these interactions. The strongest interaction was observed for the HTcO₄–tryptophan with an energy minimum of -9.53 kJ/mol at a distance of 2.1 Å. Phenylalanine showed a similarly strong interaction, with a minimum of -9.49 kJ/mol, while tyrosine exhibited the weakest interaction, with a minimum of -8.61 kJ/mol. Electrostatic potential maps confirmed the electrostatic nature of the C–H···O interactions, highlighting the role of the oxygen atoms in acting as hydrogen bond acceptors. These findings suggest that the position of the hydrogen atoms relative to the substituents on the aromatic ring influences the strength of the interactions. The results presented here could be of great importance for the recognition of new, overlooked noncovalent contacts between pertechnetic acid and amino acid fragments and a better understanding of the stability of pertechnetate-peptide complexes.У овом раду су проучаване C–H···O интеракције између HTcO₄ и ароматичних аминокиселина (фенилаланин, тирозин и триптофан) коришћењем квантнохемијских прорачуна. Резултати прорачуна енергије интеракција су комбиновани са анализом молекулских електростатичких потенцијала (MEП) ради бољег разумевања природе ових интеракција. Најјача интеракција је израчуната у систему HTcO₄–триптофан са минимумом од -9,53 kJ/mol на растојању од 2,1 Å. Фенилаланин је показао сличну јачину интеракције (9,49 kJ/mol), док тирозин има најслабију интеракцију (-8,61 kJ/mol). Анализа мапе електростатичког потенцијал је потврдила електростатичку природу C–H···O интеракција, наглашавајући улогу атома кисеоника као акцептора водоника у водоничним везама. Ови резултати пружају значајан увид у улогу C–H···O интеракција у молекулском препознавању и дизајну функционалних материјала са пертехнетатским јединицама. Добијени резултати указују да положај атома водоника у односу на супституенте на ароматичном прстену утичу на енергију ових интеракција. Ови резултати могу бити од великог значаја за препознавање нових нековалентних контаката између пертехницијумове киселине и фрагмената амино киселина, као и за боље разумевање стaбилности комплекса пертехнетата и пептида.This is the acceoted version of the manuscript: Bigović, Miljan, Veljković, Ivana, Petrović, Jelena, Veljković, Dušan, "Quantum-chemical study of C–H···O interactions between HTcO₄ and aromatic amino acids" in Journal of the Serbian Chemical Society, 90, no. 6 (2025):741-752 [https://doi.org/10.2298/JSC250125013B]Published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/9152
Silica matrix-driven modulation of ferrite nanoparticles: Insights into synthesis, coercivity and magnetization
No full textThis study introduces a thermal decomposition synthesis method to synthesize bare and embedded cobalt ferrite nanoparticles in a silica matrix, enabling a direct comparison between them to examine agglomeration and particle size effects on magnetic properties. XRPD confirmed the cubic spinel structure, with reduced crystallinity in the composite due to the amorphous silica. FTIR analysis verified CoFe2O4 incorporation into silica, showing metal–oxygen (560–410 cm−1) and Si–O–Si (1030 cm−1) bonds. TEM revealed agglomerated particles (≈30 nm) in bare CoFe2O4, whereas the composite exhibited smaller (≈20 nm), dispersed nanoparticles within the silica. The XPS spectra confirm that the Fe and Co ions in both samples exhibit oxidation states of Fe3+ and Co2+. Magnetic characterization showed contrasting behaviors: bare CoFe2O4 exhibited higher coercivity at 300 K (1509 Oe) but lower at 5 K (7172 Oe) compared to the composite (1073 Oe and 8407 Oe, respectively). These trends were linked to particle size distributions, with the silica matrix promoting smaller superparamagnetic nanoparticles and reduced inter-particle interactions. These behaviors are driven by the interplay between superparamagnetic and ferrimagnetic nanoparticle populations. The silica plays a key role in controlling particle size, agglomeration and magnetic properties, offering insights into tailoring nanocomposites for data storage, biomedicine, and catalysis. Future work should optimize cobalt ferrite weight percentages in the silica matrix to achieve control over particle size and agglomeration.Published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/8399]This is accepted, peer-reviewed version of: L. Andjelković, M. Šuljagić, V. Pavlović, A. Mraković, M. Panjan, J. Kovač, M. Tadić, Silica matrix-driven modulation of ferrite nanoparticles: Insights into synthesis, coercivity and magnetization, Inorganic Chemistry Communications (2025), doi: [https://doi.org/10.1016/j.inoche.2025.114137
Polyphenol Extraction from Teucrium montanum Using Fluidized Bed
No full textFluidized beds are systems that ensure efficient contact
between the solid phase and the fluid, making them suitable for extraction
processes. In this study, a fluidized bed was used for the extraction of
polyphenols from plant material. Polyphenols are micronutrients and natural
antioxidants found in fruits, vegetables, plants, and nuts, obtained through
extraction from plant materials. Extracting polyphenols from medicinal
plants is particularly important, as these compounds can be utilized in
medicine, cosmetics, and the food industry. The quality of the obtained plant
extracts depends on the choice of solvent and the applied extraction method.The objective of this study is to optimize the extraction of
polyphenols from Teucrium montanum by evaluating three different
methods: (1) a fluidized bed of plant material, (2) a three-phase fluidized bed
with inert particles, and (3) conventional maceration. All extractions were
performed at room temperature to preserve the stability of thermolabile
polyphenols. Water and a fifty percent aqueous ethanol solution were used as
solvents.The extraction kinetics of total polyphenols were
monitored to evaluate the efficiency of all three extraction methods. The
results showed that both fluidization techniques yielded a higher polyphenol
extraction rate compared to conventional maceration. The study also showed
that a higher polyphenol yield is obtained when a 50% aqueous ethanol
solution is used as the extraction solvent.Poster: [https://cer.ihtm.bg.ac.rs/handle/123456789/8882
Advanced Approach towards Electrochemical Oxidation and Determination of Aripiprazole Using Gold and Boron-Doped Diamond Electrodes
No full textThe antipsychotic drug aripiprazole (ARP) can be determined at the trace level in biological samples employing an easy-to-use and very sensitive electrochemical approach. The cyclic voltammetric behavior of ARP at the gold (Au) electrode and the boron-doped diamond electrode (BDDE) was investigated and suggested that the ARP oxidation process is irreversible and adsorption controlled.The morphology of ARP on the Au electrode surface was studied using optical microscopy and atomic force microscopy techniques. The various experimental parameters of the SW-AdSV method were optimized for the quantitative determination of ARP at the anodically pretreated BDDE (+2.4 V; 60 s). Under optimized conditions (pH 3.0; accumulation potential (Eacc) of 0.5 V and accumulation time (tacc) of 180 s), a linear concentration range was from 0.10 ng ml−1 to 16.91 ng ml−1, while the relative standard deviation did not exceed 4.6%, and the evaluated detection limit (LOD) was 0.03 ng ml−1. The interference study confirmed adequate selectivity of the proposed SW-AdSV method and BDDE towards ARP. During the analysis of ARP in spiked urine sample, good recovery and reproducibility were achieved, suggesting a good
application capability and reliability of the developed voltammetric method for monitoring ARP in biological samples
Poster: "Bioleaching as a tool for waste valorization and metal extraction"
No full textBauxite is the primary ore for aluminum production, while red mud is a highly alkaline and toxic waste by-product of alumina extraction via the Bayer process. This process generates significant environmental challenges due to the large quantities of waste produced and the hazards associated with its disposal. Despite containing valuable elements like iron, aluminum, and titanium, conventional red mud disposal methods, such as landfilling, present ecological risks. Bioleaching, which employs microorganisms to extract metals from ores and waste, presents a sustainable alternative. This study explored the bioleaching potential of Acidithiobacillus ferrooxidans (strain B2 from lake Robule, Bor, Serbia) for processing bauxite (particle size >125 μm) and red mud. A 28-day leaching experiment was conducted using a neutralized 9K medium, with final pH values of 3 for red mud and 1 for bauxite. Results confirmed the microorganisms effectiveness in metal recovery, as determined by inductively coupled plasma mass spectrometry (ICP-MS) analysis. Both abiotic and biotic leaching of bauxite recovered certain amounts of cerium, copper, neodymium, zinc, and yttrium, along with smaller quantities of lanthanum, praseodymium, samarium, thorium, erbium, and ytterbium. For red mud, abiotic leaching showed no change after 28 days, whereas biotic leaching recovered notable amounts of yttrium (from 282 to 10958 μg/L), cerium (from 126 to 7781 μg/L), neodymium (from 212 to 7176 μg/L), and other elements. Biotic leaching consistently yielded higher recovery rates compared to abiotic methods, highlighting the potential of Acidithiobacillus ferrooxidans as an effective agent for metal recovery from industrial waste.Poster presented at the IX International Congress Engineering, Environment and Materials in Process Industry EEM 2025. Abstract: [https://cer.ihtm.bg.ac.rs/handle/123456789/8455]