Nataliya Kutsevol

In situ formation of silver nanoparticles in linear and branched polyelectrolyte matrices using various reducing agents.

Silver nanoparticles were synthesized in linear and branched polyelectrolyte matrices using different reductants and distinct synthesis conditions. The effect of the host hydrolyzed linear polyacrylamide and star-like copolymers dextran-graft-polyacrylamide of various compactness, the nature of the reductant, and temperature were studied on in situ synthesis of silver sols. The related nanosystems were analyzed by high-resolution transmission electron microscopy and UV-vis absorption spectrophotometry. It was established that the internal structure of the polymer matrix as well as the nature of the reductant determines the process of the silver nanoparticle formation. Specifically, the branched polymer matrices were much more efficient than the linear ones for stable nanosystem preparation.

Star-like dextran-polyacrylamide polymers: Prospects of use in nanotechnologies

Branched star-like dextran-polyacrylamide copolymers in nonionic and ionic forms are used as matrices for the fabrication of silver nanoparticles. It is demonstrated that due to the features of their molecular structure providing a high local concentration of functional groups, branched polymers stabilize silver nanoparticles more efficiently as compared with their linear analogs. Stable silver colloids are obtained in a branched anionic matrix, meanwhile a linear matrix does not stabilize a nanosystem.

Features of the intramolecular structure of branched polymer systems in solution

The review is devoted to the synthesis and properties of branched polymer structures of a controlled molecular architecture. The work considers the main methods to obtain branched macromolecules. The results of both theoretical calculations and experimental studies of the structure and features of the behavior of the mentioned systems in solution are analyzed and generalized. The promising use of branched polymer systems as an alternative to linear systems is noted.

Dextran-Polyacrylamide as Matrices for Creation of Anticancer Nanocomposite

Drug targeting to specific organs and tissues is one of the crucial endeavors of modern pharmacotherapy. Controlled targeting at the site of action and reduced time of exposure of nontargeted tissues increase the efficacy of the treatment and reduce toxicity and side effects, improving compliance and convenience. Nanocarriers based on the branched copolymers dextran-graft-polyacrylamide were synthesized and characterized and were tested on phagocytic cells. It was shown that these nanoparticles are actively captured by phagocytic cells and that they are not cytotoxic. The polymer nanoparticles loaded with cisplatin at different concentrations from 0.1 to 10 μg/mL yielded dose-dependent decrease in viability of chronic myelogenous leukemia and histiocytic lymphoma cells. The lowest percentage of viable cells was observed for lymphoma cells (22%). Taking into account the fact that our nanoparticles will act mainly on malignant phagocytic cells and do not affect healthy cells, they can thus potentially be used for the therapeutic treatment of tumor cells having phagocytic activity. The effect of nanosilver on cell viability was lower than the one of polymer/cisplatin composite. The data from the cytotoxic studies indicate that nanosilver induces toxicity in cells. However, when the copolymers were conjugated to both nanosilver and cisplatin, such a nanosystem displayed less cytotoxic effect compared to the conjugates of dextran-polyacrylamide and cisplatin.

Synthesis, Morphology, and Optical Properties of Au/CdS Hybrid Nanocomposites Stabilized by Branched Polymer Matrices

Metal/semiconductor Au/CdS nanocomposites were synthesized in the solution of branched D-g-PAA polymer. TEM and DLS of Au/CdS/D-g-PAA nanocomposites revealed complicated nanocomposite structure consisting of the Au nanoparticles NPs of 6 nm in size surrounded by small CdS NPs with size of 3 nm. These nanocomposites formed the aggregates-clusters with average size of 50–800 nm. Absorption spectra of Au/CdS nanocomposites consist of the bands of excitons in CdS NPs and surface plasmons in Au ones. The surface plasmon band of gold NPs is red shifted and broadened in Au/CdS/D-g-PAA nanocomposites comparing to the one of Au NPs in Au/D-g-PAA proving the fact of close location of CdS and Au NPs in the synthesized Au/CdS/D-g-PAA nanocomposites. The PL spectra of Au/CdS nanocomposites originate from the radiative transitions in excitons in CdS NPs. The 4-fold increase of intensity of free exciton PL is observed for CdS NPs in Au/CdS/D-g-PAA comparing to CdS ones in CdS/D-g-PAA that is due to PL enhancement by local field of surface plasmons of Au NPs. Also, the 12-fold decrease of intensity of localized exciton PL is observed for CdS NPs in Au/CdS/D-g-PAA comparing to CdS ones in CdS/D-g-PAA. Most probably, it is due to passivation of the surface of CdS NPs carried out by the Au ones.

About the compatibility of polymer components in polymer complexes based on poly(acrylamide) and poly(vinyl alcohol)

The issue of applying the usual concepts of polymer compatibility to nonstoichiometric PVA/PAA mixtures of chemically complementary poly(vinyl alcohol) and poly(acrylamide), which form in water solution InterPC (intermolecular polymer complex) stabilyzed by H-bonds, and PAA to PVA graft copolymers (PVA-PAA N ) with different grafted chains number N, that are IntraPC (intramolecular polymer complexes) is discussed. PVA and PAA are compatible on molecular level. At the same time PVA/PAA mixture (50/50 W/W) is characterized by heterogeneous structure consists of InterPC with φ char =9g PVA /g PAA and the excess of unconnected PAA. In the case of IntraPC, yet, only PVA-PAA N , where N=25, is characterized by a single glass transition temperature (Tg). At larger values of N separate PAA domains form giving rise to the corresponding Tg. These results are discussed in view of IntraPC structure peculiarities as a function of N investigated by IR spectroscopy.

A new triple system DNA-Nanosilver-Berberine for cancer therapy

The isoquinoline quaternary alkaloid Berberine possesses a variety of pharmacological properties that suggests its promising application for an anticancer delivery system design utilizing its ability to intercalate DNA. In the current work, we have investigated the effects of Berberine on the human T cell leukemia cell line in vitro. Fluorescent microscopy of leukemic cells revealed Berberine nuclear localization. The results showed that Berberine inhibited leukemic cell growth in a time- and dose-dependent manner, that was associated with reactive oxygen species production intensification and caspase 3/7 activity increase with followed apoptosis induction. Berberine was used as a toxic and phototoxic agent for triple system synthesis along with DNA as a carrier and nanosilver as a plasmonic accelerator of Berberine electronic transitions and high energy emission absorbent centers. The proposed method allows to obtain the complex of DNA with Berberine molecules and silver nanoparticles. The optical properties of free components as well as their various combinations, including the final triple system DNA-Nanosilver-Berberine, were investigated. Obtained results support the possibility to use the triple system DNA-Nanosilver-Berberine as an alternative therapeutic agent for cancer treatment.

Synthesis of Silver Nanoparticles in Star-Like Dextran-Graft-Polyacrylamide Matrices

Branched copolymers Dextran-graft-Polyacrylamide (D-g-PAA) with star-like architecture of macromolecules and linear Polyacrylamide (PAA) were used for in situ synthesis of Ag nanoparticles. Aqueous silver colloids were characterized by UV-vis spectroscopy, TEM and dynamic light scattering. The internal structure of polymer matrices in solution affects the Ag nanoparticle formation and stability of colloid systems. Branched structure of D-g-PAA macromolecules provides obtaining of stable silver colloids even at high temperature when linear PAA matrix is not efficient.

Comparative Study of Branched and Linear Polymers for the Regulation of Clay Dispersion Stability

Two series of Dextran-graft-Polyacrylamide copolymers with Dextran backbone of different molecular masses and different numbers of PAA grafts have been synthesized and characterized. Their abilities for the stabilization or destabilization have been examined for a kaolin suspension of moderate concentration within the nephelometric method. The analyzed copolymers have been found to be stabilizers of the suspension when applied in low doses and to be flocculants when applied in moderate or high doses. The mentioned properties are dependent on both molecular mass of a copolymer, as well as on its molecular architecture.

Influence of the Nature of Counterions and Solvent on the Structure of PSS Solutions

We have studied by Small Angle X-ray Scattering (SAXS) semidilute solutions of the acid H+- and salt Na+-forms of polystyrene sulfonate (PSS) in water and organic solvents: DMSO and ethanol. The solutions in water were prepared without and with specific added low-molecular-weight electrolytes: NaCl, 1-ethyl-3-methylimidazolium tosylate and tosylic acid, or p-toluenesulfonic acid. We have shown that the Na+–H+ counterion exchange influences the effective charge fraction of the PSS macroions and hence their average conformation in water. However, the added low-molecular-weight electrolytes have none distinct effect on the SAXS profile of the acid form polystyrene sulfonate (PSSH) aqueous solutions. We conclude that, contrarily to the valence, the chemical nature of low-molecular-weight cations does not determine their condensation on macroanions. By using different solvents we can change the polyelectrolyte behavior, or structure. In particular for PSS, the replacement of water by the organic solvents DMSO and ethanol led to the appearance of a solvophobic effect.