Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological Polymers

Abstract

Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins can be expensive and their mechanisms of action are not understood, limiting their translation, especially into biomedical cryopreservation applications. Here well-defined poly(vinyl alcohol), synthesized by RAFT/MADIX polymerization, is investigated for its ice nucleation inhibition (INI) activity, in contrast to its established ice growth inhibitory properties and compared to other synthetic polymers. It is shown that ice nucleation inhibition activity of PVA has a strong molecular weight dependence; polymers with a degree of polymerization below 200 being an effective inhibitor at just 1 mg.mL–1. Other synthetic and natural polymers, both with and without hydroxyl-functional side chains, showed negligible activity, highlighting the unique ice/water interacting properties of PVA. These findings both aid our understanding of ice nucleation but demonstrate the potential of engineering synthetic polymers as new biomimetics to control ice formation/growth processes

Grafting of Polymer Brushes from Xanthate‐Functionalized Silica Particles

“…PVAc was used as ap recursor of poly(vinyl alcohol) (PVA), an important general-purposepolymer.PVA is widely used for various applications,s uch as biocompatible materials, colloidal dispersion stabilizers, adhesives, and antifreeze agents. [37][38][39][40][41][42][43][44][45] Althoughs ome studies concerning PVAb rushes have been reported, [52] there are still no reports on the synthesis of PVA brusheswith aw ell-defined structure and an arrow molar mass distribution, because the methodsf or the preparation of the precursor PVAc are ATRP and iodine-mediated systems, which are not suitable for obtaining well-definedP VAc. In addition, analysiso ft he characteristics of the obtained PVAb rushes has been insufficient.P VA is generally synthesized by hydrolyzing PVAc under alkaline conditions.…”

“…Poly(vinyl alcohol) (PVA), which can be relatively easily be prepared by hydrolysis of PVAc, is an extremely useful polymerw ith many applications, such as biofunctional materials, adhesives, colloid dispersants, anda ntifreeze coating agents. [37][38][39][40][41][42][43][44][45] It is therefore surprising that well-defined PVA brushesh ave never been synthesized by any SI polymerization techniques.…”

Regioregular Alternating Polyampholytes Have Enhanced Biomimetic Ice Recrystallization Activity Compared to Random Copolymers and the Role of Side Chain versus Main Chain Hydrophobicity

“… 22 − 24 It should be noted that this is distinct to PVA’s role in nucleation inhibition. 25 , 26 The role of architecture on PVA’s activity has been studied by Gibson and co-workers with the IRI activity increasing with chain length, with a minimum of 10–20 units being essential. 27 , 28 Voets et al found that comb-like PVAs had lower activity compared to linear.…”

Polymer mimics of biomacromolecular antifreezes

“…5c ) 81 . The exact link between ice nucleators and antifreezes remains unclear, but it has been shown that synthetic AFGP mimics also demonstrate some nucleation inhibition properties 82 . In short, this process remains open for study and is even less studied than the already complex IRI mimetics.…”

“…a Multi-point freezing assay used to assess ice nucleation, nucleating droplets are circled in red 82 ; b Carbon nanomaterials with ice nucleation activity: (i) carboxylated graphene nanoflakes, (ii) mellitic acid, (iii) graphene oxide, (iv) multiwalled carbon nanotubes and (v) single walled carbon nanotubes 81 ; c Graphene oxide-polymer composites 82 . a and c are reproduced from Biggs et al (2017) 82 with permission of PCCP owner societies. These images are not included under the creative commons licence for this article.…”