Vol 74, No 6 (2019)

Abstract—A catalyst based on ionic liquid consisting of a pyridinium cation having Brønsted acidity and a molybdenum anion (1-butyl-3-carboxypyridinium molybdate) is obtained. Its catalytic activity in the oxidation of sulfur-containing compounds is studied. The influence of the oxidation’s duration, temperature, and the quantity of the oxidation agent and catalyst on the conversion of dibenzothiophene (DBT) is also considered. The conversion of DBT is 100% in the presence of the catalyst under the following conditions: molar ratio H₂O₂ : S = 10 : 1, catalyst mass 0.02 g, reaction temperature 50°C, and duration 120 min.

Abstract—Molecular heterogeneity in seven human metastatic melanoma cells lines is revealed using a double immunofluorescent assay by flow cytometry. It is evaluated that quite a small population of cells (up to 10%) expressed only vimentin, the main marker of melanoma. Only epithelial cytokeratins expression is revealed in a significantly greater number of cells (from 25 to 50%). The dominant molecular phenotype (50–80% cells expressed both markers), the coexpression of vimentin and cytokeratins, is identified for the first time. The authors assume that the latter phenotype of melanoma cells may be a molecular marker of the tumor’s aggressiveness and metastatic potential.

Abstract—Both synthetic and natural polymers are promising carriers for the immobilization of enzymes, including lipases from different sources. This research trend is of fundamental and applied importance, since immobilized lipases are widely used in various biotechnological processes. In the present work, we study how synthetic and natural polymers (polystyrene, polylysine, and chitosan) influence the catalytic properties of lipases from the hog’s pancreatic gland (LPP), yeast fungus Сandida cylindracea (LCC), and wheat germs (LWG) in the hydrolysis of triacetin (used as a substrate in all the experiments). A polystyrene-based latex (even without surface modification) is found to have a strong effect on the activity of lipases of different origins. In the presence of large particles with a size of about 1 μm (irrespective of their concentration in the range of 1–10%), the activity of all three lipases (LPP, LCC, and LWG) significantly increases compared to the nonimmobilized enzyme. A polystyrene latex with a carboxylated surface shows another effect on the catalytic properties of these lipases. The activity of LPP is found to depend on the concentration of chitosan (at ratios ranging from 100 : 1 to 1 : 1), as well as on the parameters of the medium (pH and temperature). The measurement of the catalytic activity of lipase with polylysine showed that, at ratios of 10 : 1 and 5 : 1 (LPP was in excess), the activity of enzyme increased by 17 and 9% relative to the free form, respectively. This is due to the interaction between the positively charged polylysine and the enzyme having an extra negative charge. The results obtained seem promising for biotechnological applications.

Abstract—An immunochromatographic test system for the combined analysis of two cardiomarkers, such as fatty acid binding protein (FABP) and troponin I (TnI), in serum and whole blood is developed. The main stages of the design of a multiparametric system are investigated, including the influence of the antibody position and gold nanoparticle size on the results. The detection limits of the method are found to be 10 ng/mL for FABP and 1 ng/mL for TnI, and the coefficient of variation did not exceed 10%. The developed test system allows us to confirm the diagnosis of acute myocardial infraction (N = 9). The analysis time is 15 min.

Abstract—Iron nanoparticles are obtained by reducing iron(III) chloride with sodium borohydride in aqueous solutions at room temperature without using stabilizing agents. The obtained samples are characterized by X-ray diffraction analysis, low-temperature adsorption of argon, and transmission electron microscopy. The effect of the concentration of reagent solutions, the molar ratio of reagents, and exposure to ultrasound and inert atmosphere (Ar) on the size and composition of the resulting particles is found. Depending on the conditions of borohydride reduction of iron salts in an aqueous solution, both agglomerates of iron nanoparticles (5–50 nm) of 200 nm or larger and individual iron nanoparticles of 1 to 20 nm in size can be obtained. The presence and concentration of wustite and magnetite in the composition of the obtained particles mainly depend on the concentration of the reducing agent.

Abstract—The presence of hydroxycinnamic acids in the leaves of Malus sylvestris Mill. and Malus domestica Borkh. is established by using HPLC analysis. The quantitative determination of hydroxycinnamic acids is carried out by spectrophotometric analysis. It is found that the maximum amount of hydroxycinnamic acids accumulates in the plant during the fruiting phase.