We have a large program to explore the use of glycans for sensing and delivery applications. All mammalian cells are covered with glycans (the glycocalyx) which is responsible for a huge range of roles, from signalling to sites for pathogen-binding. We have previously explored how we can use metabolic oligosaccharide engineering to install non-natural glycans (sugars) onto cell surfaces, allowing us to 'do chemistry' on the cell surface in a bio-orthogonal manner. In this work, led by Prof Ben Boyd (Monash University), we explore how different cell types take up and display a cyclo-alkene (suitable for 'click' chemistry) bearing glycan, and use these differences to capture nanoparticles (with azides) onto the surface of the cells, leading to internalisation. Cells with the fastest growth rate processed the glycan faster, and hence lead to more nanoparticle capture. As cancerous cells are often characterized by increased metabolic rates, this may offer an opportunity to improve the targetting of nano-therapeutics by the highly selective formation of a covalent bond, rather than relying on unspecific physicochemical properties or targetting ligands.

Read the work here!

Understanding Selectivity of Metabolic Labelling and Click-Targeting in Multicellular Environments as a Route to Tissue Selective Drug Delivery

We have a large program to explore the use of glycans for sensing and delivery applications. By installing glycans, using a polymeric tether, onto gold nanorods we can exploit their unique optical properties, allowing us to detect if a protein binds to the glycans. Rod-shaped (compared to spherical) gold particles are exciting, as they have an additional SPR ('colour') band, which does not overlap wiht the background from e.g. blood/serum, unlike spherical gold. In our latest paper we explore how the proteins found in serum can impact on this biosensing due to non-specific fouling (sticking to form a biocorona) to the particle surface. This is a major challenge in nanomedicine/diagnostics as this fouling always occurs. Indeed, we observed that serum proteins do bind to the nanoparticles, and compared the biosensing in comparison to a model buffer solution. Interestingly, despite the biocorona formation we could still detect a lectin (glycan binding protein) BUT, it was show that the response was due to displacement of the biocorona. This meant that after binding there was less mass on the surface, than before, which was not expected. This displacement mechanism is useful as it shows our polymer-tethering strategy can be used to prepare nanoparticles suitable for use in complex media. This was a collaboration with VITO in belgium as part of a EU wide project.

Read the paper here

The Polymeric Glyco-Linker Controls the Signal Outputs for Plasmonic Gold Nanorods Biosensors due to Biocorona Formation

Red blood cells underpin larges amounts of trauma medicine, and other areas. TO ensure constant supply, one solution is to freeze (cryopreserve) the blood, and this is currently achieved by using glycerol. Before the blood cells can be transfused the cryooprotectants must be washed away, using a series of washing buffers, which leads to some loss of RBCs. In our latest publication, we explored alternative cryoprotectants based on DMSO and trehalose, with the addition of a polyampholyte, which we have previous found to be useful for the cryopreservation of nucleated cells. Following a screen of the different compositions, we identified a mixture which enabled <3 % post-thaw heamolysis (damaged blood cells). Following washing the total recovery was 80 %, which considered this was done manually, with no automated washing was a very signifcant result. We used microscopy and ATP assays to further confirm these results and even showed the system works in a 'blood bag'.

Read the work here

Red Blood Cell Cryopreservation with Minimal Post-Thaw Lysis Enabled by a Synergistic Combination of a Cryoprotecting Polyampholyte with DMSO/Trehalose,

We have a significant research program exploring and discovering new tools to improve cellular cryopreservation. We have been particularly interested in how to cryopreserve cell monolayers - cells attached to the tissue culture plastic. in our latest work (and the final publication from Trisha Bailey's PhD) we looked at the impact of proline (the amino acid) on cryopreservation outcomes. Extremophile rganisms produce proline in anticipation of cold stress, along with other osmolytes. However, we saw here that proline appears to slow the growth rate of cells in culture and 'prepare' them for cold stress, whereas other osmolytes had their normal function only. This pre-incubation dramatically increases post-thaw recovery of the cells and provides a simple tool for improving outcomes. Furthermore this shows we might be able to use chemical biology tools to program cells to be 'ready for cold'.

Read the paper here

Proline pre-conditioning of cell monolayers increases post-thaw recovery and viability by distinct mechanisms to other osmolytes

The Royal Society is running a campaign to promote the benefits of the UK being able to access EU funding opportunities. The GibsonGroups work has been highlighted, specifically on how the EU funding (ERC starter grant) provided long term fundamental science support, but also allowed translational opportunities via proof of concept grants. The Group's work in this are has lead to the formation of a spin out company, Cryologyx Ltd, which would not have been possible without this support.

Read it here

Our latest work on non-standard ice binding materials has been published in Nature Communications. In this work, we used phage display - a high -throughput technique which enabled billions of short peptides to screened for their ability to bind ice crystals. This lead to the discovery a small, 14 amino acid, cyclic peptide sequence which was a potent ice growth inhibitor. This work was a collaboration with Harm-Anton Klok (EPFL Switzerland) and Dr Corey Stevens, who visited Warwick several times to undertaken much of this research. We also collaborated with the Sosso Group at Warwick, who provided modelling expertise to understand how such a small peptide can bind ice. The peptide was also used as a 'CryoTag' to enable purification of proteins by a simple ice-binding process. The work is important as this peptide is easy to synthesise by solid phage peptide synthesis, allowing access for more experiments and can be easily modified for further study.

Read the paper here

A Minimalistic Cyclic Ice-Binding Peptide from Phage Display

We have a major research interest in how we can develop new materials, inspired by extremophiles, which can bind or modulate ice growth and also macromolecular cryoprotectants to protect cells/proteins from cold damage. A key challenge is that discovering new materials which affect ice growth is challenging (compared to the well known ice binding proteins). In our latest paper we report that polymer nanoparticles, derived from PISA (polymerization-induced self-assembly) had the surprising property of preventing ice recrystallization (growth). What was surprising was that the coronal polymer (water soluble outside parts) alone had no activity, but in the PISA particle format showed a remarkable enhancement, with larger particles being more active than small. One polymer, polyvinylpyrrolidone, appear to bind ice crystals when in particle format, which has not been previously reported. The results are really exciting as these are really very easy to synthesise and a huge range of monomers and particle morphologies can be accessed and will let us explore these properties. We also showed these polymers do not nucleate ice formation, as few materials do. This was important as large assemblies of ice binding proteins have been shown to nucleate ice, but that was not seen here.

The paper has been published in the Journal of the American Chemical Society, read here -

Polymer Self-Assembly Induced Enhancement of Ice Recrystallization Inhibition

Our Spin-out Company, Cryologyx, has secured additional investment and closed its first investment round. This goes alongside a large grant from Innovate UK. Cryologyx is a biotechnology company aiming to bring new cryopreserved products, and underpinning technologies, to market and is led by former PhD and PDRA Dr Tom Congdon.

Read the press release here.