α,α-trehalose/water solutions.: 5.: Hydration and viscosity in dilute and semidilute disaccharide solutions

We report viscosity and compressibility measurements of trehalose, maltose, and sucrose aqueous solutions at different concentration and temperature values. What emerges from the concentration dependence of viscosity and compressibility is that trehalose, in comparison to maltose and sucrose, shows a higher interaction strength with water, which gives rise to a greater value of the hydration number throughout the investigated temperature range. Furthermore, viscosity measurements reveal that at high concentration values, trehalose shows a "stronger" kinetic character than the other disaccharides, namely, a lower structural sensitivity to temperature changes in the investigated temperature range. This result could explain the greater cryptobiotic attitude of trehalose at high concentrations. The present work, which consists of quantifying experimentally the basic hydration behavior and solution structure of the investigated disaccharides as a function of concentration and temperature, allows the working hypothesis of the several existing simulation approaches to be tested.