Comparison of thermophysical properties in disaccharide aqueous solutions

To get some insight into the mechanisms of cryopreservation that characteri ze disaccharides, and to clarify the reasons that make trehalose the most e ffective bio-protector, we report measurements on trehalose, maltose, and s ucrose aqueous solutions. To analyse the interaction mechanisms of the thre e homologous disaccharides with water, we have investigated the volumetric properties of the three disaccharide solutions, by performing density and u ltrasonic velocity measurements at different concentration and temperature values. In addition, we analyse the thermal properties of trehalose, maltos e and sucrose aqueous solutions by using Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA). What emerges from these studies is that t rehalose shows, in comparison with maltose and sucrose, the smallest values of the partial molar volume in all the investigated temperature range, thi s circumstance being indicative of a more packed conformational arrangement especially at the lowest temperatures. Furthermore, trehalose reveals, in respect to the other disaccharides, the greatest structural sensitivity to temperature changes. Finally, calorimetric measurements indicate a greater effectiveness of trehalose in destroying the tetrahedral network of water c ompatible with the formation of ice, supporting the hypothesis of a higher "fragile" thermodynamic character of the trehalose-water system at high dil ution. PreliminaryTGA and DTG findings reveal a noticeable stronger trehalo se-water interaction mechanism and a significant higher thermal stability o f the trehalose system.