Effect of tetrasodium tripolyphosphate on the freeze-concentrated glass-like transition temperature of sugar aqueous solutions.

The freeze-concentrated glass-like transition temperatures (Tg2), so-called ante-melting temperature or ice-melting temperature of tripolyphosphate-sugar aqueous solutions prepared with various sugars (ribose, sorbitol, glucose, maltose, sucrose, and trehalose) were investigated by using differential scanning calorimetry to evaluate the effect of tetrasodium tripolyphosphate on the Tg2 of sugar aqueous solutions. The Tg2 of tripolyphosphate-sugar aqueous solutions were higher than those of tripolyphosphate or sugar aqueous solutions and converged in a narrow temperature range of 238 to 243 K. Furthermore, a study of the Tg2 of tripolyphosphate-glucose aqueous solutions adjusted to various ratios indicated that the Tg2 increment depended on the ratio and that another glass-like transition appeared at a temperature below the Tg2 by increasing the ratio of tripolyphosphate. The drastic increase in the Tg2 of sugars with the addition of tripolyphosphate will be useful for improving the cryostabilization of biomaterials.