Moscow University Chemistry Bulletin最新文献

This study presents polymer-colloid nanocontainers based on water-soluble, drug, biocompatible, and biodegradable anionic polysaccharides such as sodium alginate and sodium hyaluronate cross-linked with calcium and magnesium ions. Doxorubicin characterized by fluorescent properties is used as a drug for immobilization by the prepared nanocontainers. An approach is proposed for the quantitative determination of the thermodynamic binding constants of doxorubicin with nanocontainers and linear polysaccharides, which is based on the ability of nanocontainers to quench the fluorescence of doxorubicin during interaction. The proposed approach allows us to quantitatively assess the ability of nanocontainers to retain doxorubicin immobilized.

The growth of antimicrobial resistance to traditional antibiotics over the past decades requires accelerating the pace of development of new approaches to reducing the activity of various infectious processes. Natural and synthetic antimicrobial peptides, as well as lipophilic low-molecular peptidomimetics, are considered as promising antibacterial agents. A scheme for obtaining and synthesizing a series of new amphiphiles based on amino acid derivatives with L-lysine residues in the polar block, L-methionine in the central fragment, and with variations in the length of the hydrocarbon radicals C₈–C₁₂ in the lipodipeptides is developed. The antibacterial activity of the synthesized samples is studied. They are highly effective against both Gram-positive and Gram-negative bacteria. Within the series, a parabolic dependence of the effectiveness of the antibacterial action on the length of the hydrocarbon radical is observed. The lead compound Lys-Met-C₁₁ with a MIC of 0.39 μg/mL has low cytotoxicity.

Regularities are investigated and a method is developed for one-stage cationization and cross-linking of potato and corn starches using sodium trimetaphosphate as a cross-linking agent. The obtained crosslinked cationic starches retain their granular structure, while the degree of crystallinity of the samples, regardless of the temperature (20–45°C), reaction time (24–96 h), and the dose of the crosslinking agent (0.05–5.0%), is reduced insignificantly. It is shown that in a one-stage process, the efficiency of the starch phosphorylation reaction decreases with an increase in the concentration of sodium trimetaphosphate in the system, while the efficiency of the cationization reaction does not change. The rate of flocculation of kaolin suspensions increases with an increase in the dose of flocculant for all types of cationic starches. Regardless of the dose, the maximum sedimentation rates of kaolin in model systems are observed when using cross-linked cationic potato starch. The results obtained can be used to develop a technology for producing biodegradable crosslinked cationic starches with the aim of their further use in polymer flooding to increase oil recovery, and also as effective flocculants for cleaning aqueous solutions as an alternative to synthetic polyacrylamide derivatives.

This article presents the results of studies of the effect of natural sorbents—glauconite and zeolite (clinoptilolite)—on the composition of tap water in Moscow. It is shown that the use of filters based on the proposed natural sorbents and biologically active additives to improve the characteristics of clean water regulated by regulatory documents is not advisable, since the quality of tap water in Moscow is high. Mineral beads are found to produce highly alkaline water with a very low redox value.

Poor water solubility, which negatively influences the bioavailability of oral medications, is typical for the vast majority of molecules (up to 70%) developed as active pharmaceutical ingredients (API). Amorphous solid dispersions of N-butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide (GML-3) with a Soluplus® polymer are developed in this study. The inclusion of GML-3, which is almost insoluble in water and has antidepressant and anxiolytic action, in the solid dispersions makes it possible to convert it from a crystalline to an amorphous state. The amorphous state of the solid dispersions is confirmed by X-ray phase analysis and differential scanning calorimetry. The interaction between the polymer and GML-3 inside the dispersions is revealed. It is possible to achieve 98.4% solubility of GML-3 in water via the preparation of GML-3 solid dispersions with Soluplus®, which solves the problem of solubility of this API.

The processes of the formation of coordination compounds in a Fe(II)–Fe(III)–L-Ala–H₂O system at 298.15 K and the ionic strength of a solution of 1.0 mol/L against the background of Na(H)ClO₄ are studied by the classical method of the Clark–Nikolsky oxidation potential. A joint analysis of the obtained experimental curves of the dependence of the electromotive force of the system on the concentration parameters of basic particles makes it possible to determine the formation of complexes with the following compositions: [FeHL(H₂O)₅]³⁺, [Fe(HL)₂(H₂O)₄]³⁺, [Fe₂(HL)₂(OH)₄(H₂O)₆]²⁺, [Fe(III)Fe(II)(HL)₂(OH)₄(H₂O)₆]⁺, [FeHL(H₂O)₅]²⁺, [Fe(HL)(OH)(H₂O)₄]⁺, and [Fe(HL)(OH)₂(H₂O)₃]⁰.

Silver nanoparticles (SNPs) stabilized by mesogenic ligands cholesterol (Ch) and thiocholesterol (TCh) are prepared by the borohydride reduction method. The average size of SNPs is (5.5 ± 1.0) nm and (2.7 ± 0.6) nm, respectively. The UV-visible spectrum of both samples shows an intense plasmonic absorption band with a maximum at 430 and 470 nm, respectively. The IR-spectroscopy results confirm the binding of surface silver atoms to the functional groups of the ligands, which are correlated with the previously obtained quantum-chemical calculations of the model systems. It is revealed that the introduction of SNPs in the liquid crystalline matrix extends the temperature range of its existence. SNPs are predominantly present in the samples in the reduced state, which is confirmed by the XRD-spectra. Based on these studies, the possibility of using such hybrid nanosystems as promising drug delivery carriers in targeted delivery systems is demonstrated.

Partition of a plane into polyominoes is a model of two-dimensional crystal structures made of molecules. A catalog and an atlas of all 3205 lattice partitions of a plane into dodecominos are created. Structural patterns of the partitions and their features in relation to molecular crystals are discussed.

Activation of the process of phospholipid peroxidation in the presence of divalent iron ions can cause cell death. It is generally accepted that the addition of different types of antioxidants should lead to the inhibition of this process. The aim of this paper is to study the effect of the carotenoid astaxanthin as an antioxidant on phospholipid peroxidation induced by iron ions in the composition of nano- and microemulsions in which the particle sizes are about 700–900 and 110–130 nm, respectively. It is shown that astaxanthin in the absence of iron ions reduced the malondialdehyde content in micro- and nanoemulsions. However, in the presence of iron ions, in the case of microemulsions, astaxanthin at a concentration of 30 μM reduces the content of malondialdehyde, and at a concentration of 5 μM, it has a prooxidant effect. Astaxanthin has no effect in the composition of the nanoemulsions. It is found that in the presence of iron ions, astaxanthin is bleached, undergoing degradation and oxidation. In the case of nanoemulsions, the bleaching rate constant is significantly higher than in microemulsions: 18.5 × 10³ M^–1 min^–1 and 2.1 × 10³ M^–1 min^–1, respectively. Thus, in the composition of nanoemulsions, astaxanthin quickly degrades and oxidizes (within 30 min), and in the composition of microemulsions, this process is slower. Possible mechanisms of interaction of astaxanthin with iron ions are discussed, which include both the formation of astaxanthin radicals and a nonradical complex with iron ions.

The studies on the use of consumer color-recording devices for chemical analysis that have appeared over the past 15 years are reviewed. The methodological techniques to improve the metrological characteristics of a digital colorimetry method at different analysis stages are described. The conditions to form an analytical signal are considered, and comprehensive approaches to expand the analytical capabilities of digital colorimetry are discussed thoroughly.