Anomalous translational diffusive processes in hydrogen-bonded systems investigated by ultrasonic technique, Raman scattering and NMR

Ultrasonic technique, Raman scattering and NMR spectroscopy are employed to study the structural and dynamical properties of aqueous solutions of alph a.alpha-trehalose, at different temperature and concentration values. What emerges is that trehalose, whose hydration number keeps almost constant wit h temperature, shows a destructuring effect on the tetrahedral network of w ater. The outstanding feature of this result is that trehalose, by such a d estructuring effect, reduces the microviscosity experienced by the diffusiv e entities. This is confirmed by a test of the Stokes-Einstein relation, wh ere an anomalous translational diffusive process, consisting in an enhanced diffusion with respect to that predicted by hydrodynamic theory under stic k conditions, is revealed. This latter finding, connected with the presence of strong solute-solvent interactions, supports the role of trehalose as a structure-breaker. (C) 2000 Elsevier Science B.V. All rights reserved.