STUDY OF THE SOLUBILIZING CAPACITY OF POLYMER-COLLOID COMPLEXES FORMED WITH SODIUM ALGINATE AND CHLORIDE HEXADECYLPYRIDINIUM

It was examined the behavior of systems which contain surfactants and biopolymers is considered by the example of cationic surfactants and sodium alginate. The rheological and surface-active properties of the systems have been experimentally investigated. It was found that the presence of oppositely charged surfactants in the solution significantly affects the properties of sodium alginate, due to the fact that associates or polymer-colloidal complexes are formed in the solution. Their formation significantly affects the solubilizing ability in relation to non-polar liquids. Hydrodynamic parameters of macromolecules of sodium alginate in comparison with macromolecules of chitosan correspond to the conformation of the loose ball. The state of the SN is determined by the pH of the medium and temperature. The increase in temperature leads to a violation of the structure of the chain, its destruction and a subsequent decrease in viscosity. At a temperature of 293K, the macromolecule is in a more ordered state. In the alkaline environment there is a change in the conformation of the macromolecule. As a result of this change, the viscosity naturally increases. This is explained by the fact that in an alkaline environment, the macromolecule acquires an excess negative charge, there is a repulsion of the carboxyl groups of the same name in the chain links. The macromolecule acquires an expanded configuration. The viscosity increases. In acidic environment, sodium alginate has almost zero charge as a result of protonation of carboxyl groups. The molecule acquires the conformation of a loose ball with the lowest value of viscosity. The isoelectric state of the alginate macromolecule is observed in the pH range of 5.5 to 6.0. The described state of the macromolecule in solution is confirmed by our calculations. The interaction of surface-active cations with carboxyl groups of SN leads first to the formation of associates, then to polymer-colloidal complexes. The association as a result of electrostatic interaction of active groups is enhanced by the hydrophobic interaction of hydrocarbon fragments of surfactant molecules with each other and with the alginate matrix. The association ends with the formation of a polymer-colloidal complex.

Polymer–Colloid Complexes Based on Cationic Imidazolium Amphiphile, Polyacrylic Acid and DNA Decamer

The solution behavior and physicochemical characteristics of polymer–colloid complexes based on cationic imidazolium amphiphile with a dodecyl tail (IA-12) and polyacrylic acid (PAA) or DNA decamer (oligonucleotide) were evaluated using tensiometry, conductometry, dynamic and electrophoretic light scattering and fluorescent spectroscopy and microscopy. It has been established that PAA addition to the surfactant system resulted in a ca. 200-fold decrease in the aggregation threshold of IA-12, with the hydrodynamic diameter of complexes ranging within 100–150 nm. Electrostatic forces are assumed to be the main driving force in the formation of IA-12/PAA complexes. Factors influencing the efficacy of the complexation of IA-12 with oligonucleotide were determined. The nonconventional mode of binding with the involvement of hydrophobic interactions and the intercalation mechanism is probably responsible for the IA-12/oligonucleotide complexation, and a minor contribution of electrostatic forces occurred. The latter was supported by zeta potential measurements and the gel electrophoresis technique, which demonstrated the low degree of charge neutralization of the complexes. Importantly, cellular uptake of the IA-12/oligonucleotide complex was confirmed by fluorescence microscopy and flow cytometry data on the example of M-HeLa cells. While single IA-12 samples exhibit roughly similar cytotoxicity, IA-12–oligonucleotide complexes show a selective effect toward M-HeLa cells (IC50 1.1 µM) compared to Chang liver cells (IC50 23.1 µM).

Stratification of polymer–colloid mixtures via fast nonequilibrium evaporation

In drying liquid films of polymer–colloid mixtures, stratification in which polymers are placed on top of larger colloids is studied.