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Ice Recrystallization Kinetics in the Presence of Synthetic Antifreeze Glycoprotein Analogues Using the Framework of LSW Theory

2009; American Chemical Society; Volume: 113; Issue: 9 Linguagem: Inglês

10.1021/jp805726e

1520-6106

Carsten Budke, Carolin Heggemann, Marius Koch, Norbert Sewald, Thomas Koop,

Freezing and Crystallization Processes

The Ostwald ripening of polycrystalline ice in aqueous sucrose solutions was investigated experimentally. The kinetics of this ice recrystallization process was studied at temperatures between −6 and −10 °C and varying ice volume fractions. Using the theory of Lifshitz, Slyozov, and Wagner (LSW), the diffusion-limited rate constant for ice recrystallization was determined. Also, the effects of synthetic analogues of natural antifreeze glycoproteins (AFGP) were studied. These analogues synAFGPmi (i = 3−5) contained monosaccharide side groups instead of disaccharide side groups that occur in natural AFGP. In order to account for the inhibition effect of the synAFGPmi, we have modified classical LSW theory, allowing for the derivation of inhibition rate constants. It was found that the investigated synAFGPmi inhibit ice recrystallization at concentrations down to ∼3 μg mL−1 or, equivalently, ∼1 μmol L−1 for the largest synAFGPmi investigated: synAFGPm5. Hence, our new method is capable of quantitatively assessing the efficiency of very similar AFGP with a sensitivity that is at least 2 orders of magnitude larger than that typical for quantitative thermal hysteresis measurements.