The Effect of Thermal Expansion of Ingredients on the Cocktails VS55 and DP6

Abstract

The formation of ice crystals is known to be lethal to biological cells. The presence of cryoprotectants at high cooling rates suppresses crystallization and promotes vitrification, where vitrification is solidification by rapid elevation of the viscosity (vitreous, in Latin, means glass). All materials have a tendency to change volume with a change in temperature, where the rate at which the volume changes with respect to the temperature is defined as the thermophysical property of thermal expansion. In the presence of a non-uniform temperature distribution in a bulky specimen, when different regions of the material tend to expand differently, mechanical stress may develop. It has been demonstrated that this mechanical stress can easily lead to macro structural damage to the cryopreserved specimen. As part of an ongoing effort to characterize the mechanical behavior of biological tissues and solutions in the cryogenic temperature range, the current study focuses on mapping the thermal expansion effect of cryoprotectants on the overall thermal expansion of cryoprotectant cocktails. Using a recently developed apparatus, the thermal expansion of the cryoprotectant components of the cocktails DP6 and VS55 were measured: propylene glycol, formamide, and DMSO. This paper includes a comparison of thermal expansion results with DSC analysis.