From ice-binding proteins to bio-inspired antifreeze materials

Abstract

Ice-binding proteins (IBP) facilitate survival under extreme conditions in diverse life forms. Successful translation of this natural cryoprotective ability into man-made materials would open up new avenues in biomedicine, agrifood and materials science. This review covers recent advances in the field of IBPs and their synthetic analogues, focusing on fundamental insights of biological and technological relevance.

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

“…To demonstrate the large range of IRI activity between some commonly used macromolecular inhibitors, the concentration dependence on the MLGS for AFGP 8 , AFP type III (AFPIII), PVA, and PEG (as a negative/weakly active) control is plotted in Figure 2 . AFGP inhibits all growth at concentrations as low as 0.005 mg mL − 1 , but for PVA 20 (one of the most active synthetic mimics reported) up to 1 mg mL −1 is required—a 200‐fold difference. The AFPIII (which is not glycosylated) showed activity between the two, inhibiting all growth at ≈0.1 mg mL −1 .…”

“…freeze-avoidance and have been extensively reviewed. [1][2][3][4] The ability to modulate ice formation and growth has vast technological importance across fields such as aerospace, [5] green energy, [6] automotive, and biology, in particular cellular cryopreservation [7][8][9][10] ; the storage of cells/tissues at subzero temperatures, which underpins many areas of modern biomedicine, clinical medicine, and basic biology. Current strategies are based on adding large volumes of (low molecular weight) cryoprotective agents such as glycerol or DMSO which enable slow freezing or vitrification.…”

“…[22] In short, it might not be that the most active IRI material is the most useful (e.g., depending on how accessible it is) and recent results suggest that IRI activity can be induced by more than one mechanism, including those which do not include ice binding. [4,24] Considering the interest in introducing IRI activity into synthetic materials, the aim of this article is to provide a concise comparison of the IRI activities of a range of biological and synthetic compounds. Here we use the "splat" assay, which is a common and easily accessible technique to evaluate IRI activity, but by no means the only method.…”

“…Antifreeze, ice‐binding and ice‐nucleating macromolecules have been discovered in a diverse range of extremophile organisms from fish to insects to plants. These are produced to enable the species to survive by promoting freeze‐tolerance and freeze‐avoidance and have been extensively reviewed . The ability to modulate ice formation and growth has vast technological importance across fields such as aerospace, green energy, automotive, and biology, in particular cellular cryopreservation; the storage of cells/tissues at sub‐zero temperatures, which underpins many areas of modern biomedicine, clinical medicine, and basic biology.…”

“…What is clear, however, is that the synthetic mimics tend to be far less active than the natural antifreezes, yet the activity appears to be sufficient to enable beneficial cryopreservation outcomes . In short, it might not be that the most active IRI material is the most useful (e.g., depending on how accessible it is) and recent results suggest that IRI activity can be induced by more than one mechanism, including those which do not include ice binding …”