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MOF-derived nanoceria/graphitic carbon nitride as an efficient electrochemical modifier for guanine sensor with diffusional response
No full textThis work presents a novel approach for the electrochemical detection of guanine (GU) using a MOF-derived nanomaterial. CeBTC MOF-derived CeO2 nanoparticles, prepared by calcination and mixed with graphitic carbon nitride (g-C3N4) were structurally and electrochemically characterized and further applied in sensing of GU. XRPD, FTIR, SEM, and XPS measurements were used to study the composition, structure, and morphology of the nanoceria/g-C3N4 electrode modifier. Electrochemical impedance spectroscopy measurements and cyclic voltammetric studies indicated an improved electrocatalytic output of nanoceria/g-C3N4 modified carbon paste electrode (MOFdCeO2/g-C3N4/CPE). The optimal content of electrode modifier in CPE, experimental conditions, and analytical technique parameters were established to achieve sensitive quantification of GU. Kinetic parameters of the electrochemical reaction of GU were determined and a diffusional response at an electrochemical sensor was achieved. The linear working range of the developed square-wave voltammetric method (SWV) in Britton Robinson buffer solution pH 3.0 at MOFdCeO2/g-C3N4/CPE was recorded from 0.5 μM to 100 μM of GU, with a detection limit of 0.12 μM. The proposed guanine sensor showed good storage stability, repeatability, and selectivity, and its real sample applicability was successfully tested by quantification of guanine in spiked urine samples, with excellent accuracy and precision
Лабораторијски мантил: од заштите до друштвеног симбола
No full textЛабораторијски мантил, обично одевни предмет дугих рукава, дужине до колена, често направљен од белог материјала густог ткања, служи као заштитни слој за научнике, здравствене раднике и раднике у хемијској индустрији и све друге који раде са опасним супстанцама. Мада се може уврстити у униформе, овај комад одеће се сматра потрошном робом, попут рукавица и хируршких маски. Као такви, мантили се ретко налазе у научним музејима, због чега је тешко пратити њихову еволуцију. Услед оскудице писаних трагова, реконструкција њиховог развоја се ослања на визуелне записе. Шегрти алхемичара на европским сликама из 16. века носе кецеље, најраније визуелне претече мантила. Три века касније, уочава се да руководиоци лабораторија не носе заштитне капуте, већ само њихови помоћници. Научници су највероватније први почели да носе беле мантиле, а крајем 19. века су ту праксу прихватили и лекари, као симбол научног приступа и санитарних услова рада. Подаци о употреби лабораторијског мантила у Србији су ограничени. На фотографији наставног особља, студенткиња и студената хемије Универзитета у Београду почетком 20. века уочава се да студенткиње и студенти носе тамне или беле мантиле, док професори и асистенти носе савремену пословну одећу. Раније само практична потреба, мантили данас симболизују ауторитет и научност, али изазивају и негативна осећања, попут стрепње.Изложено на Националном научном скупу "Друштвени живот моде у Србији од 19. века до данас", у оквиру сесије "Генерацијско, културно и професионално разликовање: мода,
потрошња и одевне праксе различитих друштвених група". Скуп одржан 23. и 24. маја 2025. године у Етнографском музеју у Београду и на Филозофском факултету Универзитета у Београду.Презентација: [https://cherry.chem.bg.ac.rs/handle/123456789/7101
Samarium-Doped PbO2 Electrocatalysts for Environmental and Energy Applications: Theoretical Insight into the Mechanisms of Action Underlying Their Carbendazim Degradation and OER Properties
No full textThis study presents the fabrication of a samarium-doped Ti/Sb-SnO2/PbO2 electrode and investigates its applications in polluted water treatment and energy conversion. Physicochemical properties were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray powder diffraction analysis, and Raman spectroscopy. The Ti/Sb-SnO2/Sm-PbO2 electrode showed 2.5 times higher oxygen evolution potential activity than the Ti/Sb-SnO2/PbO2 electrode. Density Functional Theory was used to conduct first-principles calculations, and the obtained results indicated that Sm doping enhances the production of reactive oxygen species. The application of the Ti/Sb-SnO2/Sm-PbO2 electrode in carbendazim (CBZ) removal was investigated, since CBZ is a fungicide whose presence in the environment, including food, water, and soil, poses a threat. After 60 min of the treatment under optimized working parameters, the degradation rate of CBZ reached 94.2% in the presence of 7.2 g/L Na2SO4 with an applied current density of 10 mA/cm2 in an acidic medium (pH 4). Of the four investigated parameters, the current density had the most significant influence on the degradation process. At the same time, the initial pH value of the solution was shown to have the least impact on degradation efficiency. These results imply a potential use of the proposed treatment for CBZ removal from wastewater
Synthesis and characterization of iridium-apigenin complexes: towards advanced catalysis and cytotoxicity
No full textApigenin (L1) is an aglycone of many natural glycosides with known biological and pharmacological activities.[1] Iridium complexes are well-known for their stability, as well as their exceptional optical and catalytic
properties.[2] The combination of iridium complexes with apigenin and its derivatives offers unique opportunities for enhancing these properties in various chemical and biological contexts. In this study, two distinct iridium complexes were synthesized: complex 1 was obtained by reacting [Ir(ppy)2Cl]2 with apigenin (L1) in the presence of a base; complex 2 was derived from the reaction of [Cp*IrCl2]2 with an apigenin derivative (C21H25O5Si2 - L2). The trimethylsilyl derivative (L2) was obtained by reacting apigenin with trimethylsilyl chloride in DCM using Et3N as a base and reflux for 16h. Both complexes were characterized by NMR and IR spectroscopies. Synthetic and purification procedures are currently being optimized. Both complexes will be tested against cancer cell lines
Smoke Without Numbers: The Duboko, Serbia Landfill Fire and the Absence of Dioxins and Furans Monitoring
No full textThis paper examines the case of a fire at the sanitary landfill Duboko – Užice, Serbia in May 2024, with particular emphasis on the institutional response and the issue of monitoring dioxins and furans. This case exemplifies a broader systemic problem: the legal framework does not adequately address the institutional responsibility for failing to engage in proactive action in urgent environmental matters, thus calling for legislative refinement and stronger enforcement mechanisms. In conclusion, the absence of monitoring for dioxins and furans during the multi-week fire at the Duboko sanitary landfill in Užice, Serbia, reveals a major failure in enforcing the Serbian Law on Air Protection and Law on General Administrative Procedure, as well as in the institutional emergency response
Elektrohemijska detekcija paracetamola u lekovima primenom elektrode od ugljenične paste modifikovane holmijum-molibdatom
No full textParacetamol (acetaminofen) je organsko jedinjenje iz grupe para-aminofenolnih derivata koje se široko primenjuje kao analgetik i antipiretik. Paracetamol, kao jedan od najčešće korišćenih lekova među odraslima i decom, zahteva pouzdane, brze i osetljive analitičke metode za kvantifikaciju u farmaceutskim proizvodima i biološkim uzorcima. Ovaj rad je fokusiran na razvoj i primenu elektrohemijske metode za određivanje paracetamola koristeći elektrodu od ugljenične paste modifikovanu holmijum-molibdatom. U radu je sintetisan i morfološki karakterisan materijal za modifikaciju elektrode primenom SEM, TEM, XRD, kao i EDS FTIR i Raman spektroskopije, a elektrohemijska analiza je sprovedena primenom ciklične voltametrije (CV), voltametrije sa pravougaonim talasima (SWV) i spektroskopije elektrohemijske impedanse (EIS). Sintetisani holmijum-molibdat poboljšava katalitička svojstva elektrode, omogućavajući smanjenje prenapona oksidacije i povećanje osetljivosti. Rezultati pokazuju da razvijeni senzor poseduje niske limite detekcije i kvantifikacije paracetamola na pH 7. Potvrđena je sposobnost senzora da detektuje niske koncentracije paracetamola u laboratorijskim uslovima, sa dobrom ponovljivošću rezultata, što ga čini pogodnim za primenu u farmaceutskoj kontroli kvaliteta i biohemijskoj analizi. Primena razvijene elektrode potvrđena je uspešnim određivanjem paracetamola u realnim uzorcima lekova
How Do the Surroundings of the C-NO2 Fragment Affect the Mechanical Sensitivity of Trinitroaromatic Molecules? Evidence from Crystal Structures and Ab Initio Calculations
No full textThe dissociation of the C-NO2 bond is the initial step in the process of the detonation of
nitroaromatic explosives. The strength of the C-NO2 bond is significantly influenced by
the relative position of the nitro group with respect to the aromatic ring plane since the
planar arrangement enables the delocalization of electron density, which strengthens this
bond. In this study, we have combined a statistical analysis of geometrical parameters
extracted from crystal structures of trinitroaromatic molecules with ab initio calculations
of non-covalent index plots and Wiberg bond index values for selected trinitroaromatic
molecules to elucidate the influence of nearby substituents on the relative position of nitro
groups with respect to the aromatic ring plane. The results of the analysis showed that
neighboring substituents have a significant impact on the geometry of nitro groups. The
results also showed that this influence arises from the repulsive interaction of voluminous
substituents, attractive non-covalent contacts, and the electronic effects of substituents
Protein Corona Stability and Removal from PET Microplastics: Analytical and Spectroscopic Evaluation in Simulated Intestinal Conditions
No full textMicroplastics entering the gastrointestinal environment rapidly acquire protein coronas
that alter their surface chemistry and analytical detectability. We investigated the physicochemical
interactions between fluorescently labeled bovine serum albumin (BSA) and
polyethylene terephthalate (PET) microplastics during simulated intestinal exposure and
evaluated the stability of the resulting hard corona. Using fluorescence tracking, SDSPAGE,
and FTIR spectroscopy, we showed that BSA forms a persistent corona that resists
oxidative-only treatments. Only a combination of oxidation with an alkaline (KOH) or
surfactant step (SDS) effectively removed the corona. None of the protocols applied affected
polymer integrity. Residual protein in less effective protocols did not show changes on PET
spectra in ATR FTIR. To validate the protocol under physiologically relevant complexity,
we extended it to PET incubated with single digestive enzymes. FTIR spectra confirmed the
removal of protein-specific signals in both systems, with no degradation of PET ester or aromatic
functional groups nor signals of protein–polymer interactions. Our results highlight
the robustness of protein–PET interactions in biological conditions and provide a variety
of protocols for protein corona removal, suitable for diverse applications of microplastic
analysis and toxicological studies
Profiling sugars and polyphenolics in raspberry cultivars ‘Willamette’ and ‘Meeker’ grown in Serbia
No full textThe commercial importance of the raspberry for Serbia is significant, as it is largely exported, with an average annual income exceeding 100 million USD. Serbia has a large raspberry production and ranks third in the world with around 98,000 t in 2023. The total area under raspberry cultivation in the Republic of Serbia is approximately 20,000 ha, of which more than 10% is organic. The aim of this study was to analyze the sugar and polyphenol profile of two raspberry cultivars (‘Willamette’ and ‘Meeker’) grown organically and conventionally in some nontraditional locations in Serbia. All organic cultivation was certified, meaning that no mineral fertilizers were used, and pest control was carried out according to theguidelines for organic cultivation. In both conventional and organic raspberries, the most abundant sugars were glucose (16.549-37.59 mg g-1) and fructose (20.468-37.706 mg g-1) and sucrose (10.01-20.79 mg g-1), while ellagic acid (552.206-1206.819 mg kg-1) and catechin (7.527-12.386 mg g-1) were the most abundant polyphenols. Sucrose, glucose, and fructose together accounted for an average of 87% of alldetected sugars. In comparison, ellagic acid accounted for an average of more than 95% of all quantified polyphenols in raspberry fruit. The sample with the highest sugar content was the organic ‘Willamette’ from the village of Krzava, while the sample with the highest polyphenol content was the organic ‘Willamette’ from the village of Sljivovo. As far as cultivars are concerned, the ‘Willamette’ cultivar showed better results in both organic and conventional cultivation compared to ‘Meeker’. Due to the compounds identified and the high sugar content, as well as the quantified polyphenolic compounds, especially ellagic acid, those two raspberry cultivars from both production systems and different locations in Serbia could be considered as functional foods
Products of interactions of domestic tea polyphenols with proteins
No full textIt has been proven that herbal teas traditionally used for nutrition have a positive effect on human health. The aim of this study was to examine the extracts of three plants in the family Lamiaceae originating from Serbia: Satureja montana L. (Rtanj tea), Salvia officinalis L. (sage), Menta spicata L. (spearmint), whose therapeutic potential is known both in traditional and modern medicine. 10% (m/m) aqueous extracts of plants were prepared. The total content of polyphenols, tannins and flavonoids was determined using the Folin-Ciocalteu's reagent and Bag's protocol i.e. aluminum-chloride method. The results obtained showed that the total content of polyphenols varied significantly in the examined plants, and the highest amount was found in the extract of Satureja montana L. The DPPH assay was used to determine the antioxidant activity of aqueous plant extracts. The content of polyphenols, tannins and flavonoids in the extracts is positively correlated with their antioxidant activity. The results of UV/VIS absorption spectrophotometry showed the presence of interactions of polyphenols in aqueous plant extracts with bovine serum albumin, which could potentially provide a prolonged antioxidant effect of polyphenols