Turans'ka S. The investigation of interphase interactions in the system water-cells-protein-silica by the methods of H NMR spectroscopy

This thesis is devoted to the investigation of basic physic-chemical regularities and the determination of interphase interaction parameters in systems containing water, live cells, protein molecules and high disperse silica by the method of H NMR with the application of the liquid phase freezing technique. It was shown for model systems that the H NMR spectroscopy method combined with the liquid phase freezing technique allows the measuring characteristics of bound water layers and the interphase interaction energy in multicomponent systems containing live cells. In terms of the interphase energy value dependence on the concentration of extracellular water the energy of intercellular interaction in the cell mass of pressed yeast was determined. In cell suspension the phase transition of sol-gel type was registered for the cell mass concentration equal to 10-12 % mass. For relatively low concentrations of cell culture in suspension when gel-like cell structures is not formed in solution, the radial dependencies of adhesion powers on the distance to cell surface were determined. Disperse silica was found to cause a strong decrease in bound water concentration in the cells-water system. The maximal decrease in interface energy was equal to 130 J/g. This value determines the maximal energy of cell interaction with the surface of silica particles. In concentrated cell suspensions cells and silica particles can form complex colloidal systems with the value of gS 2 times lower than that in the binary system. It was shown that the peculiarity of adsorbed water layer at the water-silica interface is a weak association of adsorbed molecules in comparison with bulk water. The influence of high disperse silica onto phase equilibrium in water suspensions containing cells and protein was studied. Concentration dependencies of interphase energy show that there is certain critical concentration of silica at which the destruction of gel-like phase cells-protein (with taking part water molecules) and the formation of newphase cells-protein-silica-water are going. For yeast with different dehydration degree the structure of intracellular water was accessed in terms of the chemical shift of protons in bound water molecules. In terms of data obtained for cells and partially hydrofobized silicas one can suppose particular state of water that is weakly associated with hydrogen bonds exists near hydrophobic loci on the surface.