HYDRATION AND TRANSPORT-PROPERTIES OF AQUEOUS-SOLUTIONS OF ALPHA-ALPHA-TREHALOSE

We report measurements of the sound velocity diffusivity and viscosity of aqueous solutions of alpha-alpha-trehalose at temperatures between 20 and 85 degrees C for volume fractions from 0.041 to 0.705. The ult rasonic data show that the mixing process is not ideal and that the tr ehalose-water interaction strength, because of the saturation of H-bon d sites, decreases with increasing concentration. Photon correlation s pectroscopy reveals marked changes in the effective diffusion coeffici ent in the dilute region over a limited temperature range. These measu rements, interpreted in conjunction with viscosity data on the basis o f a model by Mooney and Padova, quantify the hydration properties of a lpha-alpha-trehalose. The dependence on volume fraction and the sensit ivity to temperature changes characterize the ''fragility'' of this di saccharide-water system. (C) 1998 American Institute of Physics.