Our latest work on developing 'smart' materials has been published in RSC Polymer Chemistry. We are very interested in antifreeze protein mimetics - polymers which can slow the rate of ice growth (know as Ice recrystalisation inhibition - IRI) which have huge potential in cryopreservation of donor cells/tissue. An underlying challenge with these materials is understanding why they work. As part of our major reserach program to investigate this, we have developed polymers with essentially zero IRI activivty - but when we apply Fe 3+ ions, the polymers activity is activated. This was acheived by installation of a catechol group at the chain end (using RAFT polymerization) which promotes the formation of star-shaped polymers are higher molecular weight, triggering activity. We believe this, or similar, tools will enable us to gain more detailed understanding of the underlying mechanisms of action. This is also an analogy to how Nature works; if more protein is needed, Arctic fish up-regulate the protein synthesis. We cannot do this in chemistry, so really on the supramolecular trigger.

Read the paper here

Our latest work on new cryopreservation methods has been featured in the leading chemistry journal, Angewandte Chemie.

Donated cells and tissue are crucial for regenerative medicine but there is a core challenge in that the cells have short life times necessitating freezing. Current methods of cryopreservation require the addition of large amounts of organic solvent, which is non ideal and can lead to processing/toxicity challenges. In our latest paper, in collaboration with Steve Armes at Sheffield, we use self-assembled polymer micelles to provide a hydrated matrix around red blood cells. Alone, these offer little protection, but in combination with ice-growth inhibiting polymers (pionneered in our group) we get remarkable levels of recovery. Furthermore, post thawing, the micelles become worm-like and form a hydrogel. This provides a new method for direct, post-thaw 3-D tissue culture and will have many applications

Read the paper here

Combining Biomimetic Block Copolymer Worms with an Ice-Inhibiting Polymer for the Solvent-Free Cryopreservation of Red Blood Cells

http://onlinelibrary.wiley.com/wol1/doi/10.1002/ange.201511454/abstract

Highlighted as a 'hot' paper by the journal and also a press released issued

A recent paper by the GibsonGroup has been highlighted in RSC Chemistry World, and also selected as a 'hot' article in Molecular Biosystems. This work, in collaboration with the FullamGroup, describes a new method for identfiying bacteria, by creating 'barcodes' describing how bacteria bind to different sugars. In the work, the team assembled small arrays of simple sugars onto a surface, and then mapped how different bacteria bind to them. This allowed a trianing matrix to be developed, so unknown bacteria could then be identified. The key to this is its simplicity and scalable to a range of different biosensory surfaces. In this preliminary work, a range of Gram Negative and Gram Postive Mycobacteria were tested and identified. This included surrogates for Mycobacterium Tubuculosis. It is hoped that this will translate to easy point of care biosensors, and to enable more effecient use of antibiotics.

Read the paper here.

Discrimination between bacterial species by ratiometric analysis of their carbohydrate binding profile

Our latest paper, in collaboration with the FullamLab (Life Sciences) has been published in Molecular Biosystems. In this work we demonstrate a new, easy, concept to the identification of Bacterial species. Recently, much interest has been placed on identifying bacteria using sequencing techniques - these are excellent, but need a culturing step and bio-film forming species are a problem. They also need signifcant infrastructure, which is a challenging in the developing world. There is also the growing problem of antibiotic resistance in developed countries.

To address this we have profiled how bacteria bind to carbohohydrates (sugars). Using a simple microwell plate, we could type the bacteira based on their profile, in essence creating a barcode. We could then use this to assign blind samples. We hope to translate this to clinically relevant strains, and also to more realistic (and cheap) detection systems.

Read the paper here (open access)

Otten, LC, Fullam, E, Gibson, M.I. Molecular Biosystems, 2016, 'Discrimination between Bacterial Species by Ratiometric Analysis of their Carbohydrate Binding Profile'

Our contribution the the Book 'Macro-Glycoligands' has been published in Methods in Molecular Biology. Our chapter is a protocol (as with the series in general) describing how to obtained well-defined polymer coated gold nanoparticles with a corona of glycans. This shares our expertise and experience in this area including trouble-shooting to enable others to make these versatile materials. In particular, the use of these to probe lectin-binding is discussed.

Read the chapter here.

Methods in Molecular Biology; Macro-Glycoligands. "Multivalent Glycopolymer-coated Gold Nanoparticles

Our latest work on multivalent glycosylated nanoparticles has been published in Journal of Materials Chemistry B. We are very interested in exploiting glycans (sugars) for biotechnological applications, particularly in infectiou disease. A key challenge is being able to monitor their binding interactions with their partner proteins (or even whole pathogens). Current methods, based on SPR, QCM, NMR etc provide a huge amount of detail but are slow and expensive requiring infrastructure. Here we made use of gold nanoparticles as the sensory component and exploited their red-blue colour shift upon protein binding to monitor their glycan binding. THis was combined with a versatile synthetic approach enabling the facile incorporation of a range of sugars onto the surface of the particles, via a polymeric tether. In addition to probing the binding interactions, we translated this into a point-of-care type biosensor baed upon multiplexing (barcoding) of the sugars to lectins and toxins. We will take this work forward in our quest to make glycan-based diagnostics.

Read the paper here;

Glycosylated Gold Nanoparticle Libraries for Label-Free Multiplexed Lectin Biosensing

Our latest work in the field of studying mimics of antifreeze proteins has been published in Nature Scientific Reports. in this paper we describe our attempts to establish a high-throughput assay to screen for Ice Recrystalisation Inhibition activity; a crucial feature in the search for new cryoprotective agents to store donor cells and organs. Here we build on previous observations that gold nanoparticle aggregation was inhibited by antifreeze proteins, but was correlated with thermal hysteresis. Here we propose a closer match to IRI activity. The assay can be conducted in 96 well plates making it far simpler than our 'splat test' which is slow and not suitable for screening. Using this assay, we observed that serum proteins have weak IRI, which is reduced upon denaturing. This lead us to study other non-antifreeze proteins for IRI, as shown in our recent Biomacromolecules paper

Read the paper here

"Gold Nanoparticle Aggregation as a Probe of Antifreeze (Glyco) Protein-Inspired Ice Recrystallization Inhibition and Identification of New IRI Active Macromolecules"

Our latest work has been published in ACS Macroletters. This is a collaboration with Rachel O'Reillys group, and was undertaken by Lewis Blackman. Complex materials containing thermoresponsive polymers have been extensively studied. However, there are still conflicting reports on their transition temperatures and hysteresis values. Here we synthesised a range of polymeric micelles with a thermoresponsive corona. By changing the nature of the core forming block, we could vary the aggregation number (number of chains per micelle) and explore the effect of this on the responsive transitions. It was found that the actual transition temperature did not strongly vary with NAgg, but that the hysteseis was strongly affected. We hypothesise that the nature of the core (whcih was in some cases relatively hydrophilic) promoted solubilisation. Importantly, this shows that the nature of the macromolecular assembly, not just the chemical structure of the polymer, is a crucial parameter in predicting the properties of such materials

Read the paper here

Effect of Micellization on the Thermoresponsive Behavior of Polymeric Assemblies