All aims and objectives of the project were met with work in each Workpackage completed. This has included nearly 50 publications and 3 patents filing as well as a major review article introducing this new field, which was published in Nature Communications.
We have made exceptional progress in Workpackages A and B which involved the design, synthesis and biophysical testing of antifreeze glycoprotein mimetic materials. In particular we have made huge strides into understanding our model polymer – poly(vinyl alcohol) (PVA) and its interaction with ice. We have developed new architectures of PVA including block copolymers and star-shaped polymers and demonstrated how the ice growth activity is not affected by these changes, with all activity being retained. We have developed new synthetic methods to allow us to access degradable polymers based on PVA, which being based entirely on a carbon backbone is normally stable in solution. Working with colleagues at Warwick, we have also employed new analytical tools including wide-angle X-ray scattering and solid-state NMR to advance our understanding of how antifreeze proteins, and polymer mimics, interact with ice. We were also able to validate our findings (biophysical and cell biology, below) against native antifreeze proteins in each case.
We have also investigated a new class of ice growth inhibitors based on poly(ampholytes) – polymers with positive and negative charged groups. Using a synthetic strategy to give alternating polymers, we were able to identify the key structural motifs needed for activity, including the role of hydrophobic groups.
As part of an unplanned collaboration with partners at Warwick, we have also developed a new class of ice growth inhibitors based on self-assembled optically pure metallo-helicies and used these to test theories about the importance of ice-binding, verses amphiphilicity, in inhibiting ice growth. Finally, we introduced polyproline as a moderately active ice growth inhibiting polymer and linked its secondary structure to the ice growth properties.
Workpackage C aimed to evaluate cryopreservation methodologies. In this we have made excellent progress and by using various cell-based models we have shown how we can increase the number of recovery cells post-thaw by modulating ice growth with our polymers. A range of cell types covering mammalian cells, blood cells, suspension and monolayer as well as bacteria cells have all been investigated and the cryoprotective benefits determined. In the next period we will investigate this further, using the panel of new polymers which we have synthesised.
