Anna Krejčová

The transcriptional alterations underlying epithelial-to-mesenchymal transition (EMT) in chemoresistant ovarian cancer remain a matter of debate, with emerging evidence pointing to tumour cell plasticity and subclone reprogramming. In this study, we developed a cisplatin-tolerant ovarian cancer model by treating the cisplatin-sensitive OVCAR-3 cell line with a single dose of cisplatin, generating the OVCAR-3 CP variant. These cisplatin-tolerant cells exhibited distinct EMT-related changes at both transcriptomic and protein levels, potentially regulated by epigenetic mechanisms. EMT profiling revealed that OVCAR-3 CP cells did not display a pronounced mesenchymal phenotype but rather retained epithelial characteristics and showed elevated expression of ALDH3A1 . In contrast, the parental chemosensitive OVCAR-3 cells expressed canonical mesenchymal markers ( CDH2, VIM, ZEB1/2, SNAIL, SLUG ) and lacked stemness marker expression. Upon xenografting, both OVCAR-3 and OVCAR-3 CP cells demonstrated phenotypic plasticity, with parental OVCAR-3 xenografts acquiring EMT-like features resembling to those observed in cisplatin-tolerant tumours. These findings suggest a decoupling of EMT from cisplatin-tolerance and instead underscore a stronger association between stemness traits and cisplatin tolerance. Our data further indicate that xenografting can induce significant cellular reprogramming. Comprehensive characterization of ovarian cancer cell-derived xenograft is therefore essential, as they represent a valuable translational platform for investigating therapy adapted ovarian cancer cells.

This paper deals with the properties and testing of newly prepared organic pigments based on melamine cyanurate containing magnesium or zinc cations depending on their composition and anticorrosive properties in model coatings. Organic pigments based on melamine cyanurate with Mg²⁺ in the form of a complex differing in the ratio of melamine and cyanurate units were prepared. Furthermore, a pigment based on melamine citrate with magnesium cation Mg²⁺, a pigment based on melamine citrate with magnesium cation, and a pigment based on melamine cyanurate with zinc cation were prepared. The properties of Mg-containing organic pigments were also compared with those of selected magnesium-containing inorganic oxide-type pigments. The above-synthesized pigments were characterized by inductively coupled plasma-optical emission spectroscopy, elemental analysis, scanning electron microscopy, and X-ray diffraction. In addition, the basic parameters that are indicative of the applicability of the pigments in the binders of anti-corrosion coatings were determined. The anti-corrosive properties of the tested pigments were verified after application to the epoxy-ester resin-based paint binder in three different concentrations: at pigment volume concentrations of 0.10%, 0.25%, and 0.50%. The anticorrosive effectiveness of pigmented organic coatings was verified by cyclic corrosion tests in a salt electrolyte fog (NaCl + (NH₄)₂SO₄) in an atmosphere containing SO₂ and by the electrochemical technique of linear polarization. Finally, the effect of the structure of the pigments on the mechanical resistance of the organic coatings was investigated. The results obtained showed that the new organic pigments exhibit anticorrosive properties, and at the same time, differences in performance were found depending on the structure of the pigments tested. Specifically, the results of cyclic corrosion tests and the electrochemical technique of linear polarization clearly demonstrated that synthesized pigments of the organic type based on melamine cyanurate containing magnesium or zinc cations ensure the anti-corrosion efficiency of the tested organic coatings. The highest anti-corrosion efficiency was achieved by the system pigmented with synthesized melamine cyanurate with magnesium cation (C₁₂H₁₆MgN₁₈O₆), whose anti-corrosion efficiency was comparable to the anti-corrosion efficiency of the tested inorganic pigment MgFe₂O₄, which was prepared by high-temperature solid-phase synthesis. In addition, these organic coatings achieved high mechanical resistance after being tested using the most used standardized mechanical tests.

This work addresses the possibilities of using synthesized novel magnesium complex dyes in zinc pigmented organic coatings based on epoxyester resin to reduce the zinc content in these coatings while maintaining or increasing the anticorrosive efficiency of them. The magnesium complexes Mg-Dye-I (C₃₄H₂₆MgN₈O₆), Mg-Dye-II (C₂₆H₁₉MgN₃O₅), Mg-Dye-III (C₁₇H₁₀MgN₂O₃), and Mg-Dye-IV (C₂₅H₁₈MgN₄O₆) with a series of azo carboxylate ligands were prepared from the diazo-coupling reaction of anthranilic acid with 5-methyl-2-phenyl-3-pyrazolone (Dye I; C₁₇H₁₄N₄O₃), anthranilic acid with naphthol AS-PH (Dye II; C₂₆H₂₁N₃O₅), anthranilic acid with 2-naphthol (Dye III; C₁₇H₁₂N₂O₃), and 2-amino-5-nitrophenol with naphthol AS-PH (Dye IV; C₂₅H₂₀N₄O₆). The synthesized novel magnesium complex dyes were characterized by analytical methods. Model coatings containing these dyes at pigment volume concentrations (PVCs) = 1, 3, 5 and 10% and zinc at a ratio of pigment volume concentration/critical pigment volume concentration (PVC/CPVC) = 0.60 were formulated to study the inhibitory properties of the individual synthesized magnesium complex dyes. Model coatings containing inorganic pigments (MgO and Ca-Mg-HPO₄) at PVCs = 1%, 3%, 5% and 10% and zinc at PVC/CPVC = 0.60 were also formulated. The coating pigmented only by zinc at PVC/CPVC = 0.60 was prepared as a standard organic coating. Corrosion resistance was also evaluated by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The properties of organic coatings were also tested using other standardized and derived corrosion tests. In addition, the mechanical properties of the studied organic coatings were determined using standard tests. The aim of the work was to verify the possible synergistic efficiency of novel magnesium complex dyes by improving the mechanical, anti-corrosion, and chemical properties of zinc pigmented organic coatings.

This article deals with the simple preparation of environmentally friendly acrylic latex binders, which are functionalized with nanoparticles of metal oxides, namely MgO, ZnO, La₂O₃ and combinations of MgO and ZnO, serving as functional components to achieve antimicrobial properties, but also to improve physical–mechanical properties and chemical resilience. The incorporation of uncoated powder nanoparticles was performed during the synthesis, using the two-stage semi-continuous emulsion radical polymerization technique, to obtain latexes containing 0.5%–1.3% nanoparticles relative to the polymer content. Changes in latex performance due to nanoparticles were compared from the point of view of the type and concentration of metal oxide nanoparticles in latex. The results of the tests showed that all types of nanoparticles showed very promising properties, while with increasing concentration of nanoparticles there was an improvement in properties. The nanoparticles in latex provided interfacially crosslinked transparent smooth coating films with high gloss and good physical–mechanical properties. Latexes containing the highest concentration of nanoparticles provided coatings with significant antimicrobial activity against all tested bacterial and fungal strains, but also in-can preservative stability of liquid latex. Furthermore, the coatings were resistant to solvents, and in addition, latexes with MgO nanoparticles showed a significant decrease in the minimum film-forming temperature, and latex with a concentration of about 1.3% MgO did not show any flash corrosion under the coating film cast on a steel substrate. The latexes containing MgO and La₂O₃ nanoparticles provided coatings that were very resistant to water bleaching.

Four new compounds from perylene dianhydride were prepared and tested for their anti-corrosion properties. Dizinc salt of perylene-3,4,9,10-tetracarboxylic acid and dimagnesium salts of perylene-3,4,9,10-tetracarboxylic acid, 5,5′-(1,3,8,10-tetraoxo-1,3,8,10-tetrahydroanthra[2,1,9-def:6,5,10-d′e′f′] diisoquinoline-2,9-diyl) bis(2-hydroxybenzoic acid) and N,N′-bis[3,3′-(dimethylamino)propylamine]-3,4,9,10-perylenediimide were characterized by analytical methods (SEM, EDX, X-ray) and parameters used in the field of paints (density, oil number and critical volume concentrations of pigment). The pigments (in a pigment volume concentration series) were used to prepare paints also containing a perylene C₂₆H₁₄N₂O₄ (Compound I) derivative pigment plus inert titanium dioxide to maintain a constant concentration of solids in the paint film. A mixture containing zinc nitroisophthalate and both the perylene derivative and titanium dioxide served as the reference material. The paints were applied to steel panels in two layers with a ruler. The organic coatings were subjected to electrochemical measurements and accelerated cyclic corrosion tests. The highest corrosion resistance was found for the coating containing C₂₄H₈O₈Mg₂. Superior to the coating containing either C₂₆H₁₄N₂O₄ or the conventional corrosion inhibitor C₈H₅N0₆-Zn, this pigment type acted mainly by a mechanism based on the compound’s complexation capacity at the metallic surface/organic coating/corrosion medium interface. The organic coatings containing perylene acid salts also attained high mechanical resistance.

Low plant species richness and abundance, as well as contamination, can lead to a lack of nutrients in the diets of pollinators. This can cause increased oxidative stress, low resistance to disease and reduced detoxification ability. We proposed three forage mixtures with different botanical compositions, all of which should provide continuous forage for a wide range of pollinators. The monitored mixtures were treated by foliar application with selenium and zinc. Both elements should increase the quality of pollen and nectar. The effect of meadow mixtures and microelements on pollinator abundance, richness, and preference was evaluated using data obtained via the line transect method. Furthermore, the amount of selenium and zinc in the flowers was determined. It was found that the microelement treatment did not have any effect on the abundance and richness of the main pollinator taxa, which were affected only by a botanical composition of meadow mixtures. However, a preference for zinc-treated forage was observed in Apis mellifera, and a preference for selenium-treated forage was observed in Bombus spp. These two eusocial taxa appear to respond to an increased amount of microelements in the treated meadow mixtures. On the contrary, Lepidoptera was tied to untreated forage, where they were probably pushed by social bee species due to the competition.

Four spectrochemical methods are employed for the determination of Tl in spruce needles: ICP-MS (inductively coupled plasma mass spectrometry), ETV-ICP-MS (electrothermal vaporisation coupled to ICP-MS) analysis of decomposed and slurry samples (SlS), and SS-HR-CS-GFAAS (solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry). The methods are compared considering practical laboratory aspects (sample pretreatment, optimisation, validation, time-consumption), as well as their analytical performance. For this specific case of Tl in spruce needles, all the methods had similar requirements regarding the time required for sample pretreatment (1–2 hours, ETV-ICP-MS, SS-HR-CS-GFAAS < ICP-MS < SlS-ETV-ICP-MS). The method optimisation can be considered as routine for ICP-MS and more complicated for slurry and solid sampling, due to the differences in the matrix of standards and samples. ICP-MS optimisation required a several dozen minutes and dozens of hours for the ETV methods, which increases operational costs. ETV-ICP-MS requires a well experienced operator, skilled in both techniques (graphite furnace and ICP-MS). The order of complexity can be classified as follows: ICP-MS < SS-HR-CS-GFAAS < ETV-ICP-MS, SlS-ETV-ICP-MS. Requirements for validation in terms of the chemicals, calibration standards, and reference and control materials are similar. Major differences were evident in time demands. The procedural LODs were found typically below 1 μg kg⁻¹ of Tl (in μg kg⁻¹): 0.18 ICP-MS, 0.010 ETV-ICP-MS, 0.024 SlS-ETV-ICP-MS and 1.2 SS-HR-CS-GFAAS, which are appropriate for the Tl levels found in environmental samples. The range of recoveries did not differ significantly for the different methods used (in %): ICP-MS 92–107, ETV-ICP-MS 90–114, SlS-ETV-ICP-MS 94.5–117 and SS-HR-CS-GFAAS 90–115. ICP-MS revealed better repeatabilities (1.9–6.2%) than the others (ETV-ICP-MS 5.2–19%, SlS-ETV-ICP-MS 6.3–17% and SS-HR-CS-GFAAS 0.17–15%), as expected. In practice, ICP-MS shows significant advantages for analysis of Tl in spruce needles. However, it is necessary to consider all of the factors discussed. ETV techniques may have a justified place in special routine applications, in which the difficult development and validation of methods is much more convenient than the daily preparation of highly resistant or otherwise complicated samples.