N. V. Zakharova

Synthesis of N-vinyl-2-pyrrolidone–3-butenoic acid copolymers as drug carriers

New water-soluble copolymers of N-vinylpyrrolidone with 3-butenoic acid were prepared by radical copolymerization initiated with azobis(isobutyronitrile) or γ-radiation. The relative activities of the monomers in copolymerization were determined. The distribution of the units in the copolymer macrochains was calculated. The composition, molecular and hydrodynamic characteristics, and acute toxicity of the copolymers were determined. The copolymers were used as carriers for rifampicin antibiotic.

Complexation of anionic copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide with aminoglycoside antibiotics

The complexation of aminoglycoside antibiotics neomycin, gentamicin, kanamycin, and amikacin in the form of free bases with carboxyl- and sulfo-containing copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide (HPMA) in water and water-salt solutions is studied by means of viscometry, equilibrium dialysis, potentiometric titration, and molecular hydrodynamics. Factors influencing the stability of formed copolymer-antibiotic complexes and determinations of their toxicity are established.

Molecular and associative properties of N-vinylpyrrolidone copolymers with N-crotonoylaminocaproic acid in dilute solutions

The random copolymers of N-vinylpyrrolidone and N-crotonoylaminocaproic acid attractive for the modification of drugs are studied by static and dynamic light scattering, viscometry, and sedimentation-diffusion analysis. The content of functional groups in the copolymers is 14.1–27.0 mol %. Analysis is performed in 0.1 N aqueous solutions of sodium acetate and dimethylformamide. The molecular characteristics of the copolymers with various composition are determined. It is shown that supramolecular structures are present in copolymer solutions and their amount depends on copolymer composition; the effect of solvent on the formation of these structures is ascertained.

Evaluation of plasma peptides extraction methods by high-resolution mass spectrometry

Monitoring of peptides offers a promising approach for the discovery of novel biomarkers, which might be valuable for detection, treatment and prevention of large variety of diseases. Development of highly effective methods for plasma peptide extraction remains an important task. In the current study, we applied different types of plasma peptide extraction approaches to reveal efficient methods which would provide the highest peptide yield. We used different combinations of plasma treatment with acetonitrile and/or urea/guanidine, protein precipitation by acetone, gel-filtration, ultrafiltration, and two types of solid phase extraction. The extracted peptides were analyzed by LC-MS/MS. The obtained results suggest that several methods, including differential solubilization, organic precipitation, as well as some variants of ultrafiltration and solid phase extraction, provide effective plasma peptide enrichment convenient for further LC-MS/MS analysis. Alas, most of the identified peptides were extracted by only one of the applied methods. Hence, it seems reasonable to consider several methods to increase the possibility of novel biomarker discovery.

Physicochemical, molecular, and biological properties of complexes formed between aminoglycoside antibiotics and some anionic copolymers of acrylic series: Part II

Physicochemical and molecular properties of complexes formed by aminoglycoside antibiotics, including neomycin, gentamicin, kanamycin, and amikacin, in the form of bases and carboxyl- or sulfo-comprising copolymers of acrylamide or N-(2-hydroxypropyl)methacrylamide have been studied. The toxicity of complexes in vitro and their antimicrobial activity are matched to their behavior in solutions. Direct dependency of toxic and antibacterial properties of polymer complexes of aminoglycoside antibiotics on their molecular characteristics and stability opens up perspectives of targeting control over their antimicrobial activity by changing the microstructure of their polymer carrier chains.

Behaviorial Features of Aqueous Solutions of Thermoresponsive and pH-Sensitive Polymers with complicated architectures

Research on self-organization and aggregation in solutions of thermoresponsive and pH-sensitive polymers with complicated architectures such as star-shaped polyoxazolines and grafted copolymers with a polyimide spine and polydimethylaminoethylmethacrylate side chains was reviewed. A statistical N-isopropylacrylamide—maleic-acid copolymer was studied for comparison. Hydrophobic blocks in the macromolecules reduced the phase-stratification temperature and changed the set of scattering species by forming monomolecular micelles. An increased intramolecular density led to slower aggregate formation in solutions of polymers with complicated architectures.

Effect of pH on the Behavior of a Random Copolymer of Acrylamide

A temperature- and pH-sensitive random copolymer of N-[3-(diethylamino)propyl]-N-methylacrylamide] and N,N-diethylacrylamide was obtained. The copolymer contained 20 mol % of amine units and had a molecular weight of 3.3 × 104. Buffer solutions containing 0.0102 g/cm3 of the synthesized copolymer were studied in the pH range of 7–13.5 by light scattering and turbidimetry. At low temperatures, macromolecules and large aggregates coexist in the solutions. The copolymer is temperature- and pH-sensitive in the studied pH range. The temperature and the width of the phase separation interval increase with increasing acidity of the medium.

Mass spectrometry analysis of the diversity of Aβ peptides: difficulties and future perspectives for AD biomarker discovery

Alzheimer’s disease (AD) is the most common neurodegenerative proteopathy worldwide and affects about 30 million patients. The currently applied AD therapy is low effective, so the development of reliable methods for early peptide/protein molecular diagnostics of AD markers remains a global task for intensive research. Mass spectrometry (MS)-based approaches seem to be the most promising tool for diagnostics due to their higher sensitivity, specificity, and multiplexing capacity compared to immune-based assays, which currently can only reliably be used for the diagnostics of already manifested AD. Among the variety of endogenous and exogenous effectors of AD progression, amyloid-beta (Aβ)-soluble neurotoxic oligomers have been considered as the most powerful agents, which trigger the formation of Aβ plaques in the brain and cause neuron destruction [1]. Some of the post-translational Aβ modifications (PTMs) have been shown to enhance its oligomerization. A special role was suggested for modifications of the zinc-binding domain [2,3], and particular effects were concluded for pyroglutamate-3, isoaspartate-7, and/or phosphoserine-8 isoforms [4–6]. Recent human brain immunostaining experiments imply a more close relation of pyroglutamate-3 isoform to AD due to its accumulation inside the neurons, while the preferential localization of the isoaspartate7 carrying isoform in the vessel walls was suggested to correlate with aging [7,8]. At the same time, MS studies of Aβ from human AD brains demonstrated a wide diversity of Aβ peptides, with 26 unique Nand C-terminal truncated proteoforms, among which the canonical Aβ1-42/1-40 comprised only ~15% [9]. Also the N-terminal truncated proteoforms are believed to predominate in the insoluble material, and C-terminal truncations are segregated into soluble aggregates. Besides this, Aβ N-terminal truncation has been considered as another possible reason of toxicity upon AD progression, whereas the non-AD senile and vascular plaques were shown to consist of only non-truncated Aβ 1-40/1-42 peptides [9]. Therefore, the analysis of diversity of Aβ peptides seems to be reasonable way to search for possible early markers, which could indicate the risk of AD onset. The analysis of soluble oligomers is complicated by the high variability of their size, while PTMs and truncated forms can be identified much more easily.

Polymeric Complexes of Ofloxacin and Their Activity Against Tuberculosis Mycobacteria

The available oral forms of the antituberculosis drug ofloxacin do not ensure its long-term supply to the blood system. New polymeric complexes of ofloxacin based on copolymers of N-vinylpyrrolidone and 2-aminoethyl methacrylate hydrochloride with molecular masses of 25,000 – 87,000 were obtained with the purpose of creating effective prolonged release forms of ofloxacin. The polymeric complexes contained 25 – 35% ofloxacin, exhibited high activity against Mycobacterium tuberculosis H37Rv, and ensured gradual release of ofloxacin (45 – 57% in 50 h) in pH 2.0 buffer at 37°C.

Molecular Properties and Aggregation of Porphyrin-modified Polysiloxane in Solutions

Molecular properties and aggregation behavior of a polysiloxane with grafted side chain groups consisting of asymmetrical hydroxy-functionalized porphyrin were studied in dilute solutions. In order to understand the mechanism of aggregation of the polymeric porphyrin derivatives, several analyses of chloroform solutions were performed permitting comparison of the data obtained by means of different techniques. Molar mass and hydrodynamic size of the macromolecules were obtained using the methods of analytical ultracentrifugation, isothermal translational diffusion, and viscometry. Long distance interactions between macromolecules in dilute solutions were detected with static light scattering. With increasing the concentration of the solutions, the electronic and fluorescence spectra bands assigned to generation of H and J aggregates became apparent. The organization of aggregates, which seemed to be favored by chloroform, was visualized by atomic force microscopy images that displayed sponge-like morphology, small triangular particles, characteristic of H aggregates, and nano or micro-structured ring geometries obtained by the side-by-side J-process, coexisting together.