Der Effekt von Nanopartikeln auf die Entwicklung der Mikrostruktur in polarem Eis
Zusammenfassung der Projektergebnisse
The polar ice sheets are a unique paleoclimate archive and the analyses of the ice allow climate reconstruction of the past million years. Natural impurities change the properties of ice in many respects and in a very subtle way. It is therefore demanding to understand the process by which impurities affect the microstructural and mechanical properties of ice. In particular, impurity-related control of ice grain size observed in glacial-period ice demands deeper understanding. Calculations predict that nanoparticles may slow down grain boundary migration and cause the small grain sizes observed in impurity-rich ice of glacial periods. The aim of this project was to elucidate the role of nanoparticles in affecting the microstructure of polycrystalline ice. We chose to focus on ice-binding proteins (IBPs) as analogues for nanoparticles interacting with ice. Ice-binding proteins can be found in several polar and coldtolerant organisms and are known to closely interact with ice and control its growth. Among other effects, they inhibit the grain growth in polycrystalline ice. However, little attention has been given to this particular IBP effect, despite its impact in nature and its relevance for potential applications. We focused on the IBP from the sea-ice microalga Fragilariopsis cylindrus, isoform 11 (fcIBP11). In collaboration with Japanese groups (ILTS Hokkaido University, AIST Sapporo and Shinshu University) we showed that fcIBP11 interacts with different faces of an ice single crystal using several binding modi. Until now, two groups of IBPs have been described, based on their activity as ice growth inhibitors: moderate and hyperactive IBPs. Although it was commonly believed that hyperactivity is related to growth inhibition of the basal faces of ice crystals, we showed that a moderate IBP as fcIBP11 can also attach to the basal faces and inhibit their growth despite its partially reversible binding. Our observations clearly indicate that fcIBP11 occupies a new position in the classification of IBPs and contribute to our understanding of interaction between macromolecules and ice and, more in general, of macromolecules and inorganic crystals. Our results with polycrystalline ice showed that the particles interacting with ice can strongly suppress and completely inhibit grain growth in polycrystalline ice. We showed this under static annealing conditions down to the nanomolar protein concentration range and also in a dynamic situation with uniaxial deformation stress (up to 0.5 MPa at −10°C and 0.2 µM fcIBP11). We observed that solutes and nanoparticles without specific ice-binding properties inhibit grain growth, probably affecting the boundary mobility and exerting a drag on the grain boundaries, but the growth inhibition is several orders of magnitude weaker than in the presence of fcIBP11. Our results demonstrate the relevance of the nature of the interaction between particles and grain boundaries in expanding the well-known Zener pinning model valid for inert particles. Extrapolating the results to a natural environment and to analyses of glacial ice, we believe that great attention must be paid not only to the size and numbers but also to the nature of the particles interacting with the grain boundaries. Furthermore, we think that fcIBP11 are well suited for applications in the fields where ice growth control is needed, like in the medical cryopreservation sector, in food storage and for technical, freeze-resistant surfaces.
Projektbezogene Publikationen (Auswahl)
- (2015) A Unique Capsular Polysaccharide Structure from the Psychrophilic Marine Bacterium Colwellia psychrerythraea 34H That Mimics Antifreeze (Glyco)proteins, Journal of the American Chemical Society, 137 (1), pp. 179-189
Carillo, S., Casillo, A., Pieretti, G., Parrilli, E., Sannino, F., Bayer-Giraldi, M., Cosconati, S., Novellino, E., Ewert, M., Deming, J. W., Lanzetta, R., Marino, G., Parrilli, M., Randazzo, A., Tutino, M. L. and Corsaro, M. M.
(Siehe online unter https://doi.org/10.1021/ja5075954) - (2016) Thermal hysteresis of antifreeze proteins considering Fragilariopsis cylindrus, Algological Studies, 151/152, pp. 69-86
Kutschan, B., Thoms, S. and Bayer-Giraldi, M.
(Siehe online unter https://doi.org/10.1127/algol_stud/2016/0252) - (2017) Location and distribution of micro-inclusions in the EDML and NEEM ice cores using optical microscopy and in situ Raman spectroscopy, The Cryosphere, 11 (3), pp. 1075-1090
Eichler, J., Kleitz, I., Bayer-Giraldi, M., Jansen, D., Kipfstuhl, S., Shigeyama, W., Weikusat, C. and Weikusat, I.
(Siehe online unter https://doi.org/10.5194/tc-11-1075-2017) - (2018) Growth suppression of ice crystal basal face in the presence of a moderate ice-binding protein does not confer hyperactivity, Proceedings of the National Academy of Sciences of the United States of America, 115 (29), pp. 7479-7484
Bayer-Giraldi, M., Sazaki, G., Nagashima, K., Kipfstuhl, S., Vorontsov, D. A. and Furukawa, Y.
(Siehe online unter https://doi.org/10.1073/pnas.1807461115) - (2018) Multiple binding modes of a moderate ice-binding protein from a polar microalga, Physical Chemistry Chemical Physics, 20 (39), pp. 25295-25303
Kondo, H., Mochizuki, K. and Bayer-Giraldi, M.
(Siehe online unter https://doi.org/10.1039/c8cp04727h)
