Conformations of polyelectrolyte molecular brushes: A mean-field theory.

We present a mean-field theory for the solution properties of polyelectrolyte molecular brushes, comprising multiple ionically charged side chains tethered to the main chain (backbone). The power-law dependences for local and large-scale conformational properties, i.e.

Preparation of N-succinyl-chitin nanoparticles and their applications in otoneurological pathology.

Succinyl-chitin (SCH) nanoparticles were obtained by acylation of partially deacetylated chitin (DCH) nanofibers. Introduction of the succinyl moiety induced a partial amorphization of DCH, as viewed by X-ray diffraction, and increased the fractal dimension of the colloids from d = 1.2 (DCH) to 1.

A Comparative Study of Modern Homology Modeling Algorithms for Rhodopsin Structure Prediction.

Rhodopsins are seven α-helical membrane proteins that are of great importance in chemistry, biology, and modern biotechnology. Any in silico study on rhodopsin properties and functioning requires a high-quality three-dimensional structure. Due to particular difficulties with obtaining membrane protein structures from the experiment, in silico prediction of the three-dimensional rhodopsin structure based only on its primary sequence is an especially important task.

Synthesis and photoluminescence properties of co-polyamides with anthrazoline-containing units in the main chain.

A series of anthrazoline-containing monomers are synthesized, and eight co-polyamides of different chemical structures, containing 1,9-anthrazoline fragments in the main chain, are obtained and investigated. Photoluminescent, stress-strain, and thermal properties of these polymers are studied. It is shown that polymers with fragments of 4,4'-(pyrido[3,2-g]-quinoline-2,8-diyl)dianiline and 4,4'-(10-methylpyrido[3,2-g]quinoline-2,8-diyl)dianiline possess an intense luminescence in the range 550-650 nm.

Novel Doxorubicin Derivatives: Synthesis and Cytotoxicity Study in 2D and 3D Models.

Multidrug resistance (MDR) of tumors to chemotherapeutics often leads to failure of cancer treatment. The aim of the study was to prepare novel MDR-overcoming chemotherapeutics based on doxorubicin (DOX) derivatives and to evaluate their efficacy in 2D and 3D in vitro models. To overcome MDR, we synthesized five DOX derivatives, and then obtained non-covalent complexes with human serum albumin (HSA).

Theory of Linear-Dendritic Block Copolymer Micelles.

A self-consistent field theory is applied to study structural properties of micelles formed upon spontaneous assembly of diblock copolymers comprising soluble dendron block covalently linked to insoluble linear block in selective solvent. The structure of spherical micelles is analyzed as a function of degrees of polymerization of the blocks and number of generations and branching functionality of the dendron block. We demonstrate that for a given molecular mass of blocks both the hydrodynamic dimensions of the micelles and the aggregation number decrease as a function of the degree of branching of the dendron block.

Pervaporation multilayer membranes based on a polyelectrolyte complex of λ-carrageenan and chitosan.

A polyelectrolyte complex (PEC) was prepared from chitosan (CS) and λ-carrageenan (λ-CAR) using a layer-by-layer deposition of polyion solutions on a plated nonporous support. This material was then used as a multilayer membrane for the pervaporation separation of aqueous ethanol solutions. The fabricated complex film (25-30μm thick) was a multilayer system (λ-CAR-PEC-CS) containing a polycation CS (MW 3.

N-[4-(N,N,N-trimethylammonium)benzyl]chitosan chloride: Synthesis, interaction with DNA and evaluation of transfection efficiency.

А novel cationic chitosan derivative, N-[4-(N,N,N-trimethylammonium)benzyl]chitosan chloride (TMAB-CS), with different degrees of substitution (DS) was synthesized by a chemoselective interaction of 4-formyl-N,N,N-trimethylanilinium iodide with chitosan amino groups using a reductive amination method. Several factors (pH, reactant ratio, reaction time, and chitosan structure) were studied for their effects on the DS of the resulting TMAB-CS. The obtained derivatives were characterized by H NMR and FTIR spectroscopy.

Two-Ply Composite Membranes with Separation Layers from Chitosan and Sulfoethylcellulose on a Microporous Support Based on Poly(diphenylsulfone-N-phenylphthalimide).

Two-ply composite membranes with separation layers from chitosan and sulfoethylcellulose were developed on a microporous support based on poly(diphenylsulfone--phenylphthalimide) and investigated by use of X-ray diffraction and scanning electron microscopy methods. The pervaporation properties of the membranes were studied for the separation of aqueous alcohol (ethanol, propan-2-ol) mixtures of different compositions. When the mixtures to be separated consist of less than 15 wt % water in propan-2-ol, the membranes composed of polyelectrolytes with the same molar fraction of ionogenic groups (-NH₃⁺ for chitosan and -SO₃ for sulfoethylcellulose) show high permselectivity (the water content in the permeate was 100%).

Self-consistent field theory of polyelectrolyte brushes with finite chain extensibility.

Polyelectrolyte brushes are formed by charged macromolecules tethered by the end segment to a solid-liquid interface. At low ionic strength of the solution, the intermolecular electrostatic interactions lead to strong stretching of the macromolecules that may, as a result, approach the limit of their extensibility (the contour length). Here, we present an analytical theory of polyelectrolyte brushes developed within the Poisson-Boltzmann approximation which explicitly accounts for finite extensibility of the brush-forming chains.

Shape-Specific Patterning of Polymer-Functionalized Nanoparticles.

Chemically and topographically patterned nanoparticles (NPs) with dimensions on the order of tens of nanometers have a diverse range of applications and are a valuable system for fundamental research. Recently, thermodynamically controlled segregation of a smooth layer of polymer ligands into pinned micelles (patches) offered an approach to nanopatterning of polymer-functionalized NPs. Control of the patch number, size, and spatial distribution on the surface of spherical NPs has been achieved, however, the role of NP shape remained elusive.

Synthesis of N-succinyl- and N-glutaryl-chitosan derivatives and their antioxidant, antiplatelet, and anticoagulant activity.

The effects of temperature, reactant ratio, pH, and reaction time were studied on the polymers formed by the reactions of succinic and glutaric anhydrides with chitosan under both homogeneous and heterogeneous conditions. As a result, protocols were developed for the synthesis of succinyl- and glutaryl-chitosan derivatives (SC and GC, respectively) with a specific degree of substitution. The polymers were characterized by NMR spectroscopy, including two-dimensional NMR techniques, that confirms N-substitution of chitosan under reaction conditions used.

Development of drug delivery systems for taxanes using ionic gelation of carboxyacyl derivatives of chitosan.

Nanoparticles of two chitosan derivatives - N-succinyl-chitosan (SC) and N-glutaryl-chitosan (GC) - were developed as passive transport systems for taxanes (paclitaxel and docetaxel) using an ionic gelation technique with sodium tripolyphosphate. These nanoparticles had an apparent hydrodynamic diameter of 300-350nm, a ζ-potential of 25-31mV, an encapsulation efficiency of 21-26%, and a drug loading efficiency of 6-13%. DLS and SLS analysis shows that the nanoparticles have a unimodal size distribution and spherical form.

O,N-(2-sulfoethyl)chitosan: Synthesis and properties of solutions and films.

A series of water-soluble sulfoethylated chitosans (SEC) with degrees of substitution (DS) up to 130% were obtained using a heterogeneous reaction of chitosan with sodium 2-chloroethanesulfonate in 85% isopropanol in the presence of NaOH. NMR and FTIR spectroscopy confirmed that sulfoethylation of chitosan preferentially happens at hydroxyl groups and to some extent at amino groups, giving mixed substituted O,N-SEC. Chitosan shows positive birefringence, whereas SEC shows negative values, indicating self-organization in dilute solution.

Effective delivery of porphyrazine photosensitizers to cancer cells by polymer brush nanocontainers.

Efficient drug delivery can be assigned to tasks that attract the most acute attention of researchers in the field of anticancer drug design. We have reported the first case of using amphiphilic polymer brushes as nanocontainers for photosensitizer delivery to cancer cells. Regular graft-copolymers of hydrophobic polyimides with hydrophilic polymethacrylic acid side chains were loaded with photosensitive dye tetra(4-fluorophenyl)tetracyanoporphyrazine (Pz) providing a sufficiently stable homogeneous fraction of fluorescent Pz-loaded nanoparticles with a size of 100-150 nm.

Surface patterning of nanoparticles with polymer patches.

Patterning of colloidal particles with chemically or topographically distinct surface domains (patches) has attracted intense research interest. Surface-patterned particles act as colloidal analogues of atoms and molecules, serve as model systems in studies of phase transitions in liquid systems, behave as 'colloidal surfactants' and function as templates for the synthesis of hybrid particles. The generation of micrometre- and submicrometre-sized patchy colloids is now efficient, but surface patterning of inorganic colloidal nanoparticles with dimensions of the order of tens of nanometres is uncommon.

Alginate-containing systems for oral delivery of superoxide dismutase. Comparison of various configurations and their properties.

The regularities of release of therapeutic antioxidant enzyme superoxide dismutase (SOD) from various alginate-based delivery systems (DS) into simulated gastric and intestinal fluids were determined. The following systems were used: Ca-alginate granules (AG) prepared by various methods, porous carbonate cores with multilayer polyelectrolyte coating as well as the new two-level DS (Ca-AG containing carbonate cores loaded with proteins). The influence of the method of granule preparation, composition of gelation bath and ionic composition of the simulated fluids on release profiles of the protein from different DS was revealed.

Charge-controlled nano-structuring in partially collapsed star-shaped macromolecules.

Hydrophobic polyelectrolytes exhibit intra-molecular nano-scale self-organization instead of macroscopic phase separation because of the interplay between short-range hydrophobic attraction and long-range electrostatic repulsion. We aim to unravel how the morphology of the intra-molecular nanostructures can be controlled through the topology of the macromolecule on one hand and by adjustable ionization on the other hand. Specifically, we focus on hydrophobic star-branched polyelectrolytes, composed of either strong or weak acidic monomers.

Formation of multicellular tumor spheroids induced by cyclic RGD-peptides and use for anticancer drug testing in vitro.

Development of novel anticancer formulations is a priority challenge in biomedicine. However, in vitro models based on monolayer cultures (2D) which are currently used for cytotoxicity tests leave much to be desired. More and more attention is focusing on 3D in vitro systems which can better mimic solid tumors.

Knock-down of Hdj2/DNAJA1 co-chaperone results in an unexpected burst of tumorigenicity of C6 glioblastoma cells.

The chaperone system based on Hsp70 and proteins of the DnaJ family is known to protect tumor cells from a variety of cytotoxic factors, including anti-tumor therapy. To analyze whether this also functions in a highly malignant brain tumor, we knocked down the expression of Hsp70 (HSPA1A) and its two most abundant co-chaperones, Hdj1 (DNAJB1) and Hdj2 (DNAJA1) in a C6 rat glioblastoma cell line. As expected, tumor depletion of Hsp70 caused a substantial reduction in its growth rate and increased the survival of tumor-bearing animals, whereas the reduction of Hdj1 expression had no effect.

Detection of experimental myocardium infarction in rats by MRI using heat shock protein 70 conjugated superparamagnetic iron oxide nanoparticle.

Unlabelled: Superparamagnetic iron-oxide based contrast agents can provide important diagnostic information regarding the assessment of cardiac inflammatory diseases. The aim of the study was to analyze whether nanoparticles conjugated to recombinant 70-kDa heat shock protein (Hsp70-SPION) can be applied for the detection of acute myocardium infarct by MRI. Cellular experiments demonstrated increased CD40-mediated uptake of Hsp70-SPIONs in comparison to non-conjugated SPIONs.

70-kDa heat shock protein coated magnetic nanocarriers as a nanovaccine for induction of anti-tumor immune response in experimental glioma.

Nanovaccines based on superparamagnetic iron oxide nanoparticles (SPIONs) provide a novel approach to induce the humoral and cell-based immune system to fight cancer. Herein, we increased the immunostimulatory capacity of SPIONs by coating them with recombinant heat shock protein 70 (Hsp70) which is known to chaperone antigenic peptides. After binding, Hsp70-SPIONs deliver immunogenic peptides from tumor lysates to dendritiс cells (DCs) and thus stimulate a tumor-specific, CD8+ cytotoxic T cell response.

Persistence length of dendronized polymers: the self-consistent field theory.

We present numerical results for the thermodynamic rigidity and induced persistence length of dendronized polymers with systematically varied topology of their grafts obtained by the Scheutjens-Fleer self-consistent field method. The results were compared to predictions of an analytical mean-field theory. The two approaches have marked different predictions.