On the Existence of Bound Water in Biological Systems As Probed by Dielectric Spectroscopy

Results of dielectric relaxation studies in this laboratory on binary aqueous solutions are summarized to look for indications of the presence of bound water. The solutes include simple inorganic and organic electrolytes, polyelectrolytes, small organic molecules and polymers. It is shown that even simple solutions exhibit a great variety of dielectric effects. It therefore appears to be impossible to unambiguously discuss dielectric spectra of complex biological tissues in which different polarization mechanisms overlap. The results for solutions taken as models for biological systems indicate two types of affected water which might be considered 'bound': dielectrically saturated water in strong electric fields and water in regions with a high concentration of other molecules. Characteristics of both states of water in mixtures are presented.