Despite over 40 years of study, the underlying mechanisms which govern the action of biological antifreezes is still poorly understood, which is in part due to their limited availability and challenging synthesis. This lack of understanding has also prevent their application for biological cryopreservation. Poly(vinyl alcohol) has been shown to display remarkable ice recrystallisation inhibition activity despite its major structural differences to native antifreeze proteins. Here controlled radical polymerization is used to obtain the first quantitative structure-activity relationships, to probe the role of molecular weight and comonomers on IRI activity. Crucially, it was found that IRI activity is 'switched on' when the polymer chain length increases from 10 and 20 repeat units. Substitution of the side chain with hydrophilic or hydrophobic units was found to diminish activity when incorporated above 20 mol %, but hydrophobic modifications to the backbone were slightly more tolerated, implying unbroken sequence of hydroxyl groups are necessary for activity. These results show the role of hydrophobicity on IRI is important, but not a guarantee of activity.Figure 1. Ice recrystallization inhibition activity of PVA homopolymers as measured by the splat assay. (A) Example micrographs showing ice crystals grown in PBS alone (upper) and with PVA351, 1 mg.mL-1); (B) IRI activity as a function of polymer concentration. MLGS = mean largest grain size relative to a PBS control, expressed as %.

Antifreeze glycoprotein mimetic behaviour of poly(vinyl alcohol): Detailed structure-ice recrystallization inhibition activity study

248th National Meeting (2014)

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