Experimental dissection of devitrification in aqueous solutions of 1,3-butanediol

Devitrification is a major problem which must be overcome for successful organ cryopreservation. Devitrification can be initiated on fracture planes and on bubbles, but the focus of attention here is on devitrification by ordinary heterogeneous and homogeneous mechanisms, which are the most relevant for organ preservation by vitrification. The purpose of the present studies was to define the devitrification process: to determine nucleation rates, ice-crystal growth rates, and the distribution of ice-crystal size and to evaluate the applicability of existing quantitative models of these processes which have successfully approximated the behavior of other aqueous systems. The present work was done using differential scanning calorimetry and cryomicroscopy. The amount of ice formed has been estimated for highly concentrated solutions. Kinetic parameters are presented here for isothermal conditions and continuous heating rate experiments. The classical theory based on the Johnson-Avrami equation has been evaluated and the results are compared with the theory of Boutron. The agreement is good for the continuous heating rate conditions, but results differ for the isothermal conditions.