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Gibson Group News

Our latest work in ACS MacroLetters

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Our latest work in the design of new materials to mimic complex glycan function and to inhibit bacterial toxins has been published in ACS Macro Letters. We have previously shown that synthetic polymers bearing carbohydrates in specific orientations or densities on polymer chains can give rise to increased affinity towards bacterial lectins (toxins) and may have application as decoys to prevent infection. However, many glycopolymers are rather basic simply having lots of glycans on a flexible polymer chain. In this work, we collaborated with Prof Filip du Prez (Gent, Belgium) using their thiolactone chemistry to enable us to introduce two functional units per repeat unit of the polymer. This was advantageous as it enabled us to mimic how GM-1 - a glycolipid on our cells - presents its glycans, but in a very simple manner. Using this, we made a library of glycopolymers with either 2 glycans or a hydrophobic unit. Using a combination of inhibitory assays and biolayer interferometry we unraveled the crucial design features to obtain highly active inhibits of lectin binding. This approach shows that moving from 'boring' homo-glycopolymers to those of increased complexity may help guide the development of materials to address the spread of infection.

Read the paper here

Double-Modified Glycopolymers from Thiolactones to Modulate Lectin Selectivity and Affinity

Sat 19 Jan 2019, 15:00 | Tags: Group News

New Glycopolymers for Toxin Inhibition is published

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Our latest work into the design of new materials to inhibit toxins has been published in JPOLA. We urgently need new strategies to combat bacterial (as well as viral and fungal) infections due to the rise of antimicrobial resistance and the rapid evolution of some pathogens. Many pathogens, such as cholera or E.Coli secrete toxic proteins which bind to carbohydrates on our cell surfaces leading, which is their first step in infection. We have a major research program into the design and synthesis of new materials which can act as decoys for these toxins, preventing the infection from occurring. In this work, we evaluated a new range of polymers which instead of just having a single monosaccharide displayed multiple different ones. Our new synthetic strategy enabled this, and the rapid testing of the polymers ability to inhibit toxins. We showed that polymers bearing two difference sugars often were more potent inhibitors than those with just a single sugar, and this seemed to be linked the total capacity of binding (i.e. how many toxins the polymer can capture) rather than the actual affinity.

Read the paper here

Comparison of Systematically-Functionalized Heterogeneous and Homogenous Glycopolymers as Toxin Inhibitors.

Wed 16 Jan 2019, 08:51 | Tags: Group News, Publication

Paper Published in Macroletters

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Our latest work has been published in ACS Macro Letters. In this work we describe a new method to covalent attached synthetic polymers to cell surfaces, enabling us to bring new functionality to them, without resorting to genetic methods. There already exist many chemistry for targetting cell surfaces, such as simple NHS esters, or lipid insertion, but we wanted to form a directed, covalent bond. Glycan metabolic labeling was exploited, whereby we added an azido-functional ManNac (a sugar) to the cells, which can be processed such that it presented an azide on the cell surface as sialic acid. We then made telechelic polymers used RAFT, adding an azide reactive strained alkyne at one end, and a fluorophore or biotin at the other. We would able to show selective conjugation and coating of the cells using these polymers, with no evidence of cytoxocity nor of morphological changes (i.e. the cells looked happy). To show that we can use this method to change the functionality of the cells, we were able to recruit streptavidin to the cell surfaces, targetting the biotin units on the polymer, which did not occur without the polymer. We think this method could be broadly used to add synthetic polymers to cell surfaces to modify their function, which may have application in therapies, cell tracking and also to ask fundamental questions about how this modification affects cell function.

Read the paper here

Engineering Cell Surfaces by Covalent Grafting of Synthetic Polymers to Metabolically-Labeled Glycans

Thu 11 Oct 2018, 11:01 | Tags: Group News, Publication

Paper Published in Langmuir

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Our latest work has been published in Langmuir, as part of a special issue focussed on Mechano- and Cryo-biology, which we were very proud to be invited to contribute too. In this work, we ask the question of 'do our antifreeze-protein mimetic polymers function the same in nanoparticle form, as in solution'. This might seem straightforward, as we know that increasing the molecular weight of our polymers, increases their activity, hence when immobilised on a nanoparticle they might be more active. We actually saw that there was no enhancement, but also no decrease (which again is a surprise as the nanoparticles have a lower molar concentration than free polymers). We made use of RAFT/MADIX polymerization to make thiol-terminated poly(vinyl alcohol) to coat gold nanoparticles for this particular work, as model nanoparticle systems, which were tunable in terms of size and composition.

Read the paper here;

Multivalent Presentation of Ice Recrystallization Inhibiting Polymers on Nanoparticles Retains Activity

Thu 11 Oct 2018, 09:23 | Tags: Group News, Publication

Professor Gibson speaks at Glycobiotechnology 2018

Professor Gibson spoke at the Glycobiotechnology 2018 event hosted at Manchester University. This was an event to celebrate and showcase UK Glycoscience research. Professor Gibson showed new research from the group in the design of dynamic glycomaterials, where we exploit polymer chemistry to control the presentation of specific glycans in response to external stimuli. He also highlighted the role of the RSC Carbohydrate Group, of which he is the present chair.

Fri 14 Sep 2018, 09:41

Professor Gibson Gives Keynote at EuCHems Conference

On 29th September, Professor Gibson gave the keynote lecture in the Biomaterials Stream of the 7th EuChems international Conference in Liverpool. In this, he discussed the groups latest research into using polymers to transform the Biologic Cold Chain. This included how to target ice crystals with polymers, and the cryopreservation of mammalian and bacterial cells as well as protein drugs.

Fri 14 Sep 2018, 09:34 | Tags: Group News

Paper in ChemEurJ; Hot paper and Media Attention

Our latest work into developing non-traditional antimicrobial agents has been published in Chemistry: A European Journal. This continues our research into cationic polymers as antimicrobial agents. In this new work, we demonstrate a semi-automated synthesis platform, which can use robotics to speed up the liquid handling, alongside exploiting photo-chemical polymerization to enable this to take place in 'open air'; this is a key step as it removes the need for sealed vials and allowed us to polymerise directly in 96 well plates. 96 well plates are industry-standard for biological screening, which enabled us to rapidly screen ~ 100 polymers for antimicrobial activity, as well as blood compatibility. Using this high-throughput approach a surprising 'hit' was found, where including 15 mol % of oligopropyleneglycol methacrylate lead to a dramatic enhancement in bacteriostatic activity, but without introducing bacteriocidal activity.

Read the paper here

Photochemical 'In-Air' Combinatorial Discovery of Antimicrobial Copolymers

The paper was also featured in the media, and highlighted by the reviewers as being a 'hot' paper.

Wed 29 Aug 2018, 12:39 | Tags: Group News, Publication

Paper Published in Biomacromolecules

Our latest cryopreservation work has been published in Biomacromolecules. This work describes the development of an 'all-polymer' cryopreservation formulation for bacteria. Bacteria are used routinely in all molecular and structural biology labs around the world and are key in many biotechnology and food processes (e.g. 'friendly bacteria' in yogurts). The bacteria are not kept continuously growing but are stored as stocks, using glycerol to reduce ice-induced damage in freezers. In this work, we were inspired by antifreeze proteins which let extremophile species survive in the coldest places on earth but used synthetic polymers, which are cheaper, more scalable and practical for daily use. We have previously shown that polymer mimics of antifreeze proteins can protect mammalian cells in DMSO-mediated cryopreservation, but the mechanisms of stress (and recovery) from cold are very different in bacteria. Here we simply used precise ratios of PEG and PVA (both are food-safe, low-cost commodity polymers) and how we can match, or outperform, glycerol in several bacteria storage scenarios.

Read the paper here;

Ice Recrystallization Inhibiting Polymers Enable Glycerol-Free Cryopreservation of Microorganisms

Mon 06 Aug 2018, 10:38 | Tags: Group News, Publication

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