New Study Solving the Puzzle of Polymers Binding to Ice for Biological Cryopreservation
Understanding the ice recrystallization inhibition (IRI) activity of antifreeze biomimetics is critical to the development of next-generation cryoprotectants. Recently, in the paper, The atomistic details of the ice recrystallization inhibition activity of PVA, which is published in the journal Nature Communications, researchers from the University of Warwick have found that, contrary to the emerging consensus, shorter or longer polymer chains of poly(vinyl)alcohol (PVA) all bind to ice.
In this study, the researchers bring together molecular dynamics simulations and quantitative experimental measurements to unravel the microscopic origins of the IRI activity of poly(vinyl)alcohol (PVA)—the most potent of biomimetic IRI agents. Contrary to the emerging consensus, the team find that PVA does not require a “lattice matching” to ice in order to display IRI activity: instead, it is the effective volume of PVA and its contact area with the ice surface which dictates its IRI strength. It is also found that entropic contributions may play a role in the ice-PVA interaction and the researcher demonstrate that small block co-polymers (up to now thought to be IRI-inactive) might display significant IRI potential. This new study clarifies the atomistic details of the IRI activity of PVA and provides novel guidelines for the rational design of cryoprotectants.
When biological materials, including cells, blood,and tissues, are frozen, the use of cryoprotectants can prevent the damage related to ice formation during the freezing process. New polymer cryoprotectants have appeared together with mature cryoprotectants, but how to precisely control the formation and growth of ice is still unknown. This is especially true for PVA, which is a seemingly simple synthetic polymer that interacts with ice. Now in this new study, the mechanism has been revealed at the atomic level by researchers at the University of Warwick.
Dr. Gabriele Sosso, from the Department of Chemistry at the University of Warwick, who is leading a substantial computational effort to investigate the formation of ice in biological matter, points out that: “With this contribution we have added a crucial piece to the puzzle of how exactly polymeric cryoprotectants interact with growing ice crystals. This is part of a larger body of computational and theoretical work that my group is pursuing with the intent to understand how cryoprotectants work at the molecular level, so as to identify designing principles that can be directly probed by our experimental colleagues.”
Professor Matthew Gibson, from the Department of Chemistry and Warwick Medical School at the University of Warwick adds: “Ice re-crystallization is a real challenge in cryobiology, leading to damage to cells but also in frozen foods or infrastructure. Understanding how even this ‘simple’ polymer works to control ice re-crystallization is a major step forward to discover new cryoprotectants, and ultimately to use them in the real world.”
References
- Bachtiger, Fabienne, et al. The atomistic details of the ice recrystallisation inhibition activity of PVA. Nature communications, 2021,1: 1-14.
- University of Warwick. Solving the puzzle of polymers binding to ice for Cryopreservation. ScienceDaily, 15 March 2021.