Hydrogen bonding and kinetic/thermodynamic transitions of aqueous trehalose solutions at cryogenic temperatures.

Carbohydrates play important roles in the survival of freeze-tolerant organisms. In order to understand the role of carbohydrates on hydrogen bonding (HB) and thermodynamic/kinetic transitions, aqueous trehalose solutions at cryogenic temperatures were analyzed using FTIR spectroscopy. Distinct changes in water-water and water-carbohydrate HB organization were identified during supercooling, freezing, and vitrification. FTIR spectroscopy revealed the kosmotropic effect of trehalose and the presence of two distinct water families in supercooled carbohydrate solutions, (1) water molecules directly associated with the carbohydrate, forming its hydration layer(s) and (2) water molecules that are involved in water-water HB in small clusters. The latter showed characteristics of water in hydrophilic confinement.