Mimicking the Ice Recrystallization Activity of Biological Antifreezes. When is a New Polymer “Active”?

• Published in: Macromolecular bioscience 2019-07, Vol.19 (7), p.e1900082-n/a
• Main Authors: Biggs, Caroline I., Stubbs, Christopher, Graham, Ben, Fayter, Alice E. R., Hasan, Muhammad, Gibson, Matthew I.
• Format: Article
• Language: English
• Subjects: Alcohols; Antifreeze proteins; Antifreeze Proteins - chemistry; Antifreezes; Binding; Biological activity; biomaterials; Climate science; cryopreservation; Crystallization; Crystals; Glycoproteins; Hydrophobic and Hydrophilic Interactions; Ice; Ice crystals; Ice formation; ice recrystallization; Macromolecules; Mimicry; Molecular modelling; polymers; Polymers - chemistry; Polyvinyl alcohol; Proteins; Recrystallization; Surface-Active Agents - chemistry
• ISSN: 1616-5187; 1616-5195; 1616-5195
• DOI: 10.1002/mabi.201900082

Antifreeze proteins and ice‐binding proteins have been discovered in a diverse range of extremophiles and have the ability to modulate the growth and formation of ice crystals. Considering the importance of cryoscience across transport, biomedicine, and climate science, there is significant interest in developing synthetic macromolecular mimics of antifreeze proteins, in particular to reproduce their property of ice recrystallization inhibition (IRI). This activity is a continuum rather than an “on/off” property and there may be multiple molecular mechanisms which give rise to differences in this observable property; the limiting concentrations for ice growth vary by more than a thousand between an antifreeze glycoprotein and poly(vinyl alcohol), for example. The aim of this article is to provide a concise comparison of a range of natural and synthetic materials that are known to have IRI, thus providing a guide to see if a new synthetic mimic is active or not, including emerging materials which are comparatively weak compared to antifreeze proteins, but may have technological importance. The link between activity and the mechanisms involving either ice binding or amphiphilicity is discussed and known materials assigned into classes based on this. The emerging field of macromolecular cryoprotectants offers opportunities in low temperature biology and engineering to modulate ice growth, inspired by antifreeze proteins. Here a range of materials, from potent to weak, are surveyed for their ice recrystallization inhibition activity and characterized by their activity and potential mechanisms of action, alongside cautionary notes to avoid false positives.