Amyloid aggregation, including aggregation and propagation of prion protein, is a key factor in numerous human diseases, so-called amyloidosis, with a very poor ability for treatment or prevention. The present work describes the effect of sulfated or sulfonated polymers (sodium dextran sulfate, polystyrene sulfonate, polyanethole sulfonate, and polyvinyl sulfate) on different stages of amyloidogenic conversion and aggregation of the prion protein, which is associated with prionopathies in humans and animals. All tested polymers turned out to induce amyloid conversion of the ovine prion protein. As suggested from molecular dynamics simulations, this effect probably arises from destabilization of the native prion protein structure by the polymers. Short polymers enhanced its further aggregation, whereas addition of high-molecular poly(styrene sulfonate) inhibited amyloid fibrils formation. According to the seeding experiments, the protein–polymer complexes formed after incubation with poly(styrene sulfonate) exhibited significantly lower amyloidogenic capacity compared with the control fibrils of the free prion protein. The cytotoxicity of soluble oligomers was completely inhibited by treatment with poly(styrene sulfonate). To summarize, sulfonated polymers are a promising platform for the formulation of a new class of anti-prion and anti-amyloidosis therapeutics.

Synthetic water-soluble polymers are increasingly used for gene delivery, stabilization, and delivery of proteins, and as prospective antimicrobial and antiviral agents. Therefore, study of their interaction with lipid membranes is of special importance. Herein, we studied interaction of aliphatic cationic ionenes (recently tested for gene delivery efficiency) differed in the length of spacer between charged groups (and therefore in charge density) with anionic lipid membrane. A range of approaches such as measurement of particle size and electrophoretic mobility, liposome integrity, ATR-FTIR spectroscopy, isothermal titration calorimetry as well as atomistic molecular modeling was used. Ionene with a spacer of 10 methylene groups has been shown to be incorporated into membrane and interact with its inner hydrophobic part in contrast to ionenes with shorter spacer, which interacted only with outer polar head groups of lipids staying at the water-membrane interface. It affects membrane integrity and results in a different behavior of the polymer-liposome complexes. These findings are relevant for potential biomedical application of ionenes, including creation of composite polymer-liposome systems for drug delivery.

Advances in the development of water-soluble nonstoichiometric polyelectrolyte complexes, which are characterized by high stability and can be involved in competitive interpolyelectrolyte reactions, are summarized and analyzed. The complexes remain stable over a wide range of external conditions (pH, ionic strength, temperature), but show a rapid, reversible and highly sensitive response to environmental changes outside this range by changing the phase state. The review considers methods of preparation and properties of nonstoichiometric polyelectrolyte complexes formed by interactions between oppositely charged polyelectrolytes. These reagents can be used for controlled modification of various surfaces, the preparation of soluble complexes functionalized by different molecules, the suppression and prevention of protein aggregation. The review briefly summarizes new types of soluble polyelectrolytes and polyelectrolyte complexes of different nature and with different structures, including biopolymers and dendrimers, suitable for solving problems in medicine and agricultural biotechnology. In order to evaluate the results achieved, there is a need to integrate and analyze the data on interpolyelectrolyte reactions, which are of most interest for a wide range of researchers. The bibliography includes 118 references.

The review concerns the results of studies on the synthesis of polyelectrolyte coatings on charged surfaces. These coatings represent nanostructured systems with clearly defined tendency to self-assembly and self-adjustment, which is of particular interest for materials science, biomedicine and pharmacology. A breakthrough in this area of knowledge is due to the development and introduction of a new technique, so-called layer-by-layer (LbL) deposition of nanofilms. The technique is very simple, viz., multilayers are formed as a result of alternating treatment of a charged substrate of arbitrary shape with water-salt solutions of differently charged polyelectrolytes. Nevertheless, efficient use of the LbL method to fabricate nanofilms requires meeting certain conditions and limitations that were revealed in the course of research on model systems. Prospects for applications of polyelectrolyte layers in various fields are discussed. The bibliography includes 58 references.

Quite recently, we reported the synthesis of supercharged polycations bearing pH-insensitive double-charged repeat units with either three or five methylene groups in the space between charges. The developed approach is based on the quaternization of the parent poly(4-vinylpyridine) with different alkylating agents, providing the possibility to perform the modification as a one-step reaction, which occurs in mild conditions with a controllable degree of conversion. In the present work, we used the above approach for preparing and investigating supercharged polyplexes (polyelectrolyte complexes of nucleic acids), in particular to elucidate the reason for the key feature, i.e., the clearly defined stability of the polyplexes formed by supercharged polyamines. The main findings of the experimental study were confirmed by the results of full atomic modeling, and the principal regularities responsible for the structure, stability, and properties of the supercharged polyplexes have been elucidated for the first time.

The use of polyelectrolytes is a prospective approach to form nanocomplexes to transport different compounds including proteins. In many cases, the bound protein should be digested after delivery to the target. In the present work, we studied proteolysis of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the complexes with polyelectrolytes. We have found polyanions to enhance the proteolytic degradation of GAPDH by proteinase K and thermolysin. This effect seems to be caused by destabilization of the protein structure. However, this destabilization is reversible since the release of the enzyme from the complexes with polymers (even tightly bound with the protein such as sulfated polymers and supercharged pyridinium polycations) was accompanied by partial or complete reactivation of GAPDH, depending on the polymers and conditions. Finally, we observed that complexation with sulfated polymers enhances the proteolytic degradation of prion fibrils by proteinase K. The obtained results can be useful for treatment of pathologies associated with amyloid aggregation.

Despite use of polyelectrolytes is considered to be a prospective approach of protein aggregation suppression, owing to formation of soluble protein-polyelectrolyte complexes, the structure of the complexes and mechanism of their formation are not sufficiently understood. The aim of this work was to study the influence of degree of polymerization on the structure and properties of formed complexes. We carried out molecular dynamics simulations of complexes of cationic protein lysozyme with highly charged polyanions – poly(styrene sulfonate) and polyphosphate – of different degree of polymerization. It has been shown that the short charged chains are bound with the protein via a great majority of repeat units, while the long chains have unbound fragments that form charged loops and tails around the protein surface. These loops were earlier suggested to provide stability of the complex. Furthermore, the charge of the complex increased with increasing length of chain. These findings are consistent with the experimentally measured zeta potential. The obtained results help to explain why polyanion protective efficiency against protein aggregation increases with increase of the degree of polymerization.

Polyelectrolytes are a prospective tool for protection of proteins against aggregation. We compared synthetic polyanion, poly(styrene sulfonate), and natural chaperones of different types, namely, GroEL-like chaperonin from Pseudomonas aeruginosa phage EL and human small heat shock protein HspB5 (alpha B-crystallin), in their ability to prevent aggregation of client proteins. At 45 degrees C, all three agents efficiently suppressed thermal aggregation of phage endolysin. At higher temperatures, HspB5 and poly(-styrene sulfonate) also inhibited endolysin aggregation, though polyanion became less efficient than HspB5 at 55 degrees C and 60 degrees C. However, the polyanion completely protected another protein, glyceraldehyde-3-phosphate dehydrogenase, even at 60 degrees C, in contrast to both natural chaperones whose effect disappeared at 50-55 degrees C. These results provide a platform for the development of artificial chaperones based on synthetic polyelectrolytes. (C) 2017 Elsevier Inc. All rights reserved.

Recently we succeeded in preventing aggregation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) using polyelectrolytes. In the present work, the range of the model proteins has been extended at the expense of lysozyme and alpha-lactalbumin that are noticeably differed by isoelectric points. Experiments were performed both at higher and lower pH values than pI. In all cases, highly charged polycation or polyanion were capable of aggregation suppression. Furthermore, GAPDH was protected efficiently by both polyanion and polycation in all selected conditions. Noteworthy, in many cases protein protection was achieved by similarly charged polyelectrolyte, and the higher level of protection by polycation was achieved at lower pH despite the weakening of the Coulomb attraction. According to molecular dynamics simulations, polycation bound only negatively charged sites and formed loops and tails around protein surface. The unbound fragments seem to determine the high solubility of the complex and hence, are favorable the protein aggregation protection. The reported results could be important as a platform for the development of artificial chaperones.

The search for new ways to suppress unwanted protein aggregation represents an important problem in modern biochemistry, bioengineering, and even medicine. Recently we succeeded in preventing the aggregation using synthetic polyelectrolytes. The present work describes a new approach to solubilizing pre-formed protein aggregates with sulfated or sulfonated polymers (polysulfoanions). For the first time it was shown that polysulfoanions are capable of solubilizing amorphous and amyloid protein inclusion bodies as well as thermal aggregates. Treatment of prion protein inclusion bodies with sulfonated polymers was shown to cause significant decrease in amyloid structure content, whereas in case of thermal aggregates of glyceraldehyde-3-phosphate dehydrogenase the observed solubilization was accompanied by a partial recovery of enzymatic activity. The suggested approach could be relevant in the task of extracting recombinant proteins from inclusion bodies and also useful in the development of amyloid disease therapy.

A systematic study of the phase behavior of products resulting from the interaction of oligomeric and high-molecular-mass styrenesulfonate anions with oligomeric and polymeric N-ethyl-4-vinylpyridinium cations in aqueous salt solutions was conducted for the first time. Unexpected and considerable differences in the stability of the resulting asymmetric polyelectrolyte complexes composed of a long cationic or anionic matrix and anionic (respectively cationic) oligomers of the same degree of polymerization were revealed. A mechanism of this phenomenon based on the difference in the conformational behavior of interacting polyions in concentrated salt solutions was suggested.

The comparison study of interaction of linear poly(2-dimethyl amino)ethyl methacrylate and its cationic nanogels of various cross-linking with both DNA and sodium poly(styrene sulfonate) has been performed. Although all amino groups of the nanogels proved to be susceptible for protonation, their accessibility for ion pairing with the polyanions was controlled and impaired with the cross-linking. The investigation of nanogels complexes with cells in culture that was accomplished by using of calcein pH-sensitive probe revealed a successive increase in the cytoplasmic fluorescence upon the growth in the cross-linking due to calceine leakage from acidic compartments to cytosol. This regularity implies that amino groups which are buried presumably inside the nanogel are protected against the ion-pairing with polyanions of plasma membrane and hence are able to manifest buffer properties while captured into acidic endosomes, i.e. possess lyso/endosomolytic capacity. These findings suggest that network architecture makes an important contribution to proton sponge properties of weak polycations.

Впервые проведено систематическое изучение фазового поведения продуктов взаимодействия олигомерных и высокомолекулярных стиролсульфонатных анионов с олигомерными и полимерными N-этил-4-винилпиридиниевыми катионами в водно-солевых средах. Обнаружены неожиданные и существенные различия в стабильности образующихся зеркально симметричных полиэлектролитных комплексов, состоящих из длинной катионной или анионной матрицы и анионных (соответственно катионных) олигомеров одинаковой степени полимеризации. Предложен механизм этого явления, основанный на разном конформационном поведении взаимодействующих полиионов в концентрированных растворах соли.

Synthetic polyelectrolytes are increasingly used for gene and drug delivery as well as for protein immobilization and preventing protein aggregation. Polysulfoanions are the most efficient suppressors of the aggregation but have the adverse effect on structure and activity of the bound enzyme. We revealed factors that control denaturation of model positively charged enzyme glyceraldehyde-3-phosphate dehydrogenase in presence of polysulfoanions and polyphosphate anions differed by degree of polymerization. The two-stage process occurred on the protein titration with polyanion. The protein structure remained practically intact up to the end of the first stage, whereas further titration on the second stage resulted in protein denaturation. The molar ratio polyanion/protein corresponding to onset of the second stage increased with elongation of chains and eventually it disappeared for highly polymerized polyanions which did not denature the protein. Elucidation of the factors caused denaturation is relevant for modeling interaction of proteins with natural polyelectrolytes.

Supercharged polycations bearing pH-insensitive double-charged units were synthesized by alkylation of poly(4-vinylpyridine) with bromo-alkyl-trimethylammonium bromides (alkyl = propyl and pentyl) yielding polymers with 3 and 5 methylene groups in spacer between charges, respectively. Virtually all charged groups of the exhaustively alkylated polycations were accessible for polyanions. The ion pairing with pyrenyl-tagged poly(methacrylate) anion which was monitored by fluorescence quenching techniques revealed pronounced binding of both polycations and relatively high water-salt stability of the complexes, in particular formed by polycation with shorter spacer. For partially quaternized (co)polymers, a decrease in alkylation degree weakened the binding in slightly alkaline solutions but markedly enhanced the interaction at pH <= 7.0 due to strengthening the systems by both H-bonds and additional ion pairing induced by protonation of the pyridine groups. The disclosed tune pH-control over the stability in neutral media could form a platform for practical implementation of the supercharging, specifically in biotechnology. (C) 2015 Elsevier Ltd. All rights reserved.

A series of nanogel particles with the growing cross-linking degree was synthesized in reverse micelles by copolymerization of a cationic monomer N,N-dimethylaminoethylme thacrylate with increasing amounts of N,N'-methylenebisacrylamide (MBA). The growth of MBA content in the studied range of 0.2-15% (mol) resulted in a regular decrease of the particles' size with a narrowing in their size distribution which occurred at the first of the cross-linker addition. In the second region, where the MBA content was more than 5% (mol), the size distribution was very narrow. The cross-linked polymers prepared at 2-5% of the cross-linker amount demonstrated a minimum size of the polyplexes and enhancement in the transfection with plasmid DNA and small interfering RNA targeted to the luciferase gene. The revealed changes in the properties of nanogels occurring upon the changes in the cross-linking degree appear to be a platform for a controlled manufacturing of efficient cross-linked cationic vectors. (C) 2015 Elsevier Ltd. All rights reserved.