Poly(vinyl alcohol) Molecular Bottlebrushes Nucleate Ice

Ice binding proteins (IBP) have evolved to limit the growth of ice but also to promote ice formation by ice-nucleating proteins (INPs). IBPs, which modulate these seemingly distinct processes, often have high sequence similarities, and molecular size/assembly is hypothesized to be a crucial determin...

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Bibliographic Details
Published in:Biomacromolecules 2022-12, Vol.23 (12), p.5285-5296
Main Authors: Georgiou, Panagiotis G., Kinney, Nina L. H., Kontopoulou, Ioanna, Baker, Alexander N., Hindmarsh, Steven A., Bissoyi, Akalabya, Congdon, Thomas R., Whale, Thomas F., Gibson, Matthew I.
Format: Article
Language:English
Subjects:
Ice
Molecular Weight
Polymerization
Polymers - chemistry
Polyvinyl Alcohol - chemistry
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Summary:Ice binding proteins (IBP) have evolved to limit the growth of ice but also to promote ice formation by ice-nucleating proteins (INPs). IBPs, which modulate these seemingly distinct processes, often have high sequence similarities, and molecular size/assembly is hypothesized to be a crucial determinant. There are only a few synthetic materials that reproduce INP function, and rational design of ice nucleators has not been achieved due to outstanding questions about the mechanisms of ice binding. Poly­(vinyl alcohol) (PVA) is a water-soluble synthetic polymer well known to effectively block ice recrystallization, by binding to ice. Here, we report the synthesis of a polymeric ice nucleator, which mimics the dense assembly of IBPs, using confined ice-binding polymers in a high-molar-mass molecular bottlebrush. Poly­(vinyl alcohol)-based molecular bottlebrushes with different side-chain densities were synthesized via a combination of ring-opening metathesis polymerization (ROMP) and reversible addition–fragmentation chain-transfer (RAFT) polymerization, using “grafting-to” and “grafting-through” approaches. The facile preparation of the PVA bottlebrushes was performed via selective hydrolysis of the acetate of the poly­(vinyl acetate) (PVAc) side chains of the PVAc bottlebrush precursors. Ice-binding polymer side-chain density was shown to be crucial for nucleation activity, with less dense brushes resulting in colder nucleation than denser brushes. This bio-inspired approach provides a synthetic framework for probing heterogeneous ice nucleation and a route toward defined synthetic nucleators for biotechnological applications.
ISSN:1525-7797
1526-4602
DOI:10.1021/acs.biomac.2c01097