Our recent paper Antifreeze Protein Mimetic Metallohelices with Potent Ice Recrystallization Inhibition Activity has been featured in Scientific American (a monthly US science magazine with a circulation ~ 0.5 million). In this article they highlgihted our collaborative work with Peter Scott and David Fox on designed amphipathic helicies which have the unique ability to slow ice crystal growth. These helicies provided understanding for how native antifreeze proteins, which are often helical, prodcue their antifreeze effects through their structure and not necessarily through a lock-and-type type interaction with the ice surface - although this is still under investigation in our lab.

Read it here

Nature-Inspired Antifreeze Molecules Could Keep Organs Fresh Longer

Our latest work in collaboration with the O'Reilly Group, undertaken by Lewis (about to start PDRA at CSIRO, Australia) has been published in ACS Macroletters. In this work, we used polymerization-induced self assembly (PISA) to encapsulate proteins within the core of polymer vesicles. PISA has several advantages include that the hydrophobic block is formed in situ from a water soluble monomer; this means that it is easy to encase the protein in the luman (core) compared to traditional methods. However, during the course of this work, we observed that the hydrophobic core (poly(hydroxylpropyl methacrylate), which is actually quite hydrated) did not form a permanent barrier. It was found to actually be permeable. Using this observation we were able to show that enzymes encapsulated within the core could catalyse reactions of externally added reagents, which could cross inside, react, and the subseqently diffuse back out. The importance of this work is it verstility; we used multiple enzymes to prove that this effect is real and also show there is some size selectivity, and these can be considered to be 'molecular sieves'.

Read the paper here

Permeable Protein-Loaded Polymersome Cascade Nanoreactors by Polymerization-Induced Self-Assembly

Our latest developments in new materials to enable the cryopreservation of donor cells and tissues has been pubished in the leading chemistry journal, Angewandte Chemie! We have a major research program into addressing the challenge of how can we enable the distribution, storage and application of therapeutic cells; simply put, donor cells (e.g. for bone marrow, transplant) cannot be stored for long at room temperature, meaning they must be frozen - cryopreserved. However, cells simply dont like being frozen, and current methods involve adding organic solvents as 'antifreeze', which is a very useful method, but is not suitable for all cell types, 100 % cell recovery is not achieved and there are some toxicity issues.

In this work, we were inspired by the secondary structure (fold) of antifreeze glycoproteins (from polar fish), and made a mimic with the same structure, but composed of different units - poly(proline). By using a single building block, this system is very easy to obtain by various synthetic or biotechnolgoical methods. We found that this very simple structure was a (moderate) ice growth inhibitor and that it had patches of hydrophobicity, which we think is essential for activity. This new material was then used to enhance the cryopreservation of cells adhered to tissue culture plastic - this is a major advance as it is hard to store cells in this format, and they are normally stored in suspension. However, most applications and studies of cells are conducted as monolayers. Our collaborator, Dr Sylvain Deville in France, provided confocal cryomicroscopy to study how the polymers interacted with the ice crystals.

Read the paper here

Polyproline is a minimal antifreeze protein mimetic and enhances the cryopreservation of cell monolayers

Matt Gibson gave an invited talk at the Newton Fund supported Glycoscience event, held in Guanajuanto, Mexico. The theme of the meeting was Biotechnology and Glycotechnology Tools for Human Health. Matt summarised the groups reserach in glycan-inspired biomaterials with a particular focus on 'easy' diagnostic tools for infection.

On 7/8 September 6 members of the group attended the RSC Carbohydrate Group's annual meeting, held at Trinity Colleage Dublin. The meeting featured many excellent talks including Plenary's from Gert-Jan Boons and the Dextra Medal winner, Carman Galan.

Our latest work on antifreeze-protein mimetic polymers has been published in ACS Macro Letters. We have a major research interest in developing polymers which can mimic the function of antifreeze proteins; specifically their ability to slow the rate of ice crystal growth (recrystallisation). Ice recrystallisation is a major problem during the cryostorage of cells for medicine, transfusion, transplant and basic cell biology, hence understanding how these polymers function will help us make new, safer regenerative medicine treatments.

We have previously shown that poly(vinyl alcohol), PVA, is a remarkable ice growth inhibtor, but we do not really understand exactly how it works. Here we used column chromtography to isolate near-monodisperse fractions of PVA. The starting polymers, made by RAFT, would normally be described as being 'well defined' with a dispersity of 1.2 However, this still contains a complex mixture. This work showed that polymers with DP = 10, when monodisperse, had a lot less activity than DP 10 with more dispersity and the activity was attributed to the high molecular weight tails. This helped to us to identify how long a polymer must be, to be active (above ~12 units) and will guide our future work.

This work was conducted by an undergraduate student, Nick Vail during his MChem placement.

Ultralow Dispersity Poly(vinyl alcohol) Reveals Significant Dispersity Effects on Ice Recrystallization Inhibition Activity

Matt, Ben and Alice attended the 3rd Ice Binding Protein Conference in Rehovot, Israel. This is the words premier gathing of scientists who work on ice binding ('antifreeze') proteins. Matt gave an invited lecture describing the groups recent successes in mimic the function of antifreeze proteins with polymers, but also lower molecular weight compounds, challenging established concepts about what is possible in this field.

Our latest work in mimicing Nature's solutions to controlling ice growth and formation has been published in Physical Chemistry, Chemical Physics. We have previously studied the use of synthetic polymers to mimic antifreeze proteins - essentially to stop ice crystals from growing larger, which has a major impact on cellular cryopreservation for regenerative medicine. However, the formation of ice (nucleation) is also an incredibly complex process which is also important in cell cryopreservation. There are few known ice nucleators and most are inorganic minerals (dust) rather than molecular systems. In this work, in collaboration with Jon Rourke, we took base washed graphene oxide (bwGO) as a scaffold to develop new nucleating agents. bwGO has epoxide groups, which we exploited to graft various thiols, including small molecules and polymers, to the surface. Using a multi-point nucleation assay we identified several candidates which were potent nucleators.

This is signifcant as it shows we can develop molecular systems to mimic ice nucleating proteins - proteins which are crucial for life, or even for making snow on ski slopes! (really..)

Read the paper here

Impact of Sequential Surface-Modification of Graphene Oxide on Ice Nucleation