Effect of pH on the Interaction between Poly(vinyl alcohol) and Ice

The development of improved cryopreservative materials is necessary to enable complete recovery of living cells and tissue after frozen storage. Remarkably, poly(vinyl alcohol) (PVA) is very effective at halting the Ostwald ripening of ice, a process believed to impart mechanical damage to cells, but the mechanism through which it does so remains unclear. Herein we quantitatively evaluate ice growth kinetics in the presence of PVA at different pH conditions and in the presence of a range of neutral salts. We demonstrate that pH, but not salt identity, plays a crucial role in PVA’s ability to halt ice grain coarsening. However, we show that favorable pH conditions are not sufficient to impart ice-halting properties to similar polyols. These findings highlight the crucial role of hydrogen bonding in PVA/ice interactions. Additionally, these results provide a convenient on/off switch for PVA/ice interactions which is a valuable tool for elucidating PVA’s mechanism of action.