48. Inorganic material, zirconium acetate, displays similar characteristics to antifreeze protein

Abstract

The unique ability of antifreeze proteins (AFPs) to inhibit ice growth and recrystallization makes them excellent candidates in a variety of fields such as cryopreservation, engineering of food, medicine, and agriculture. However, the production of AFPs is highly expensive and inefficient compared to other cryo-protectant substances used in industry. These obstacles can be overcome by finding synthetic substitutes with similar AFP properties. Recently it has been shown that Zirconium acetate (ZRA) displays ice shaping habits like those of AFPs (Deville et al., 2011). Our study is focused on finding additional antifreeze properties in ZRA, which are crucial to estimate its potential as a cryoprotectant. First we measured the growth rate of ice crystals in the presence of 30 g/ml ZRA (pH 4.2) along the a- and the c-axes, and found a significantly lower growth rate compared to ice crystal growth in 100 mM acetate buffer (pH 4.2). We then measured recrystallization in which larger ice crystals grow at the expense of smaller ones, thus reducing the surface energy of the system. Recrystallization was clearly observed in the acetate buffer readily after only a few seconds and the median ice crystal diameter increased. In contrast, in solutions containing ZRA or AFP, recrystallization was completely inhibited. The ability of ZRA to inhibit ice recrystallization and to reduce ice crystal growth rate imply on its tremendous potential usages in the field of cryopreservation and other biological and engineering fields. Supported by ISF, ERC and IRG.