Gibson Group News
Dan M becomes Dr Number 6!
Daniel Mitchell has become the most recent PhD to graduate from the lab. He defended his Thesis, examined by Daniell Mitchel (Warwick Medical School) and Vitaly Khutoryanskiy (Reading). Dan's Thesis was on the design of new antifreeze protein mimetic polymers and their translation to cell cryo-storage applications.
Read some of his papers, below;
Mitchell, D. E., et al. (2014). "Quantitative study on the antifreeze protein mimetic ice growth inhibition properties of poly(ampholytes) derived from vinyl-based polymers." Biomaterials Science. 2014, 2 (12), 1787 - 1795Mitchell, D.E, et al. (2015).
"Rational, yet simple design of an antifreeze protein inspired polymer for cellular cryopreservation". Chemical Communications. 2015, DOI: 10.1039/C5CC04647E.
Methods In Molecular Biology Book Chapter Published
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.
Caroline Becomes a Dr!
Caroline Biggs has become the 5th Dr To emerge from the group, having succesfully passed her viva with Dr Andrew Marsh (Warwick) and Prof Paula Mendes (B'Ham) acting as the examiners.
Carolines PhD was entitled ' Biointegrative Polymer Surfaces' and focused on the development of new surface coatings to enable us to probe biological function at complex surfaces, with a particular focus on polymeric tethers for glycans.
Read some of carolines papers below
Richards, SJ, Biggs, CI, Gibson, MI, 2016, Series Vol 1367, Methods in Molecular Biology; Macro-Glycoligands. "Multivalent Glycopolymer-coated Gold Nanoparticles" e-book ISBN 978-1-4939-3130-9; Hard Cover ISBN 978-1-4939-3129-3Congdon, T., Dean, B.T., Kasperczak-Wright, J., Biggs, C.I., Notman, R., Gibson, M.I., Biomacromolecules 2015, 16, 2820 – 2826 , Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological PolymersBiggs, CI., Edmondson, S,,and Gibson, M.I., Biomater. Sci., 2015, 3, 175 - 181, "Thiol-ene Immobilisation of Carbohydrates onto Glass Slides as a Simple Alternative to Gold-Thiol Monolayers, Amines or Lipid Binding
Paper published in Journal of Materials Chemistry
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;
Paper Published in Nature Scientific Reports
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
Paper Published in ACS MacroLetters
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
Paper published in Polymer Chemistry
Or latest paper has been published in RSC Polymer Chemistry. This is a collaboration with Jon Rourke and Neil Wilson (physics). Since its discovery, a huge number of scientists (academic and industrial) have sought to investigate the applications of graphene, and its relatives carbon nanotubes. It's unique 2-D structure gives rise to intresting properties, but a key challenge lies in ensure it can be compatitablised - mixed - with other components. To acheive this polymer conjugation is a useful approach. This is normally acheived through complex multi-step procedures. Here we show that base-washed graphene oxide (an easy and scalable derivative of graphene) can be modified by RAFT-ed polymers by ring-opening of surface epoxides using the thiol-end group. This was proven using a range of high resolution analytical techniques, including solid state NMR, TEM and XPS. We beleive the simplicity of the method will enable more complex hybrid material to be developed.
Read the paper here
One-step grafting of polymers to graphene oxide"
Paper Published in Biomacromolecules
Our latest work on antifreeze protein mimetic macromolecules has been published in ACS Biomacromolecules. We are seeking to understand and explain ice recystallisation inhibition - a unique property associated with antifreeze proteins which we have shown to be a useful property to enhance cryopreservation (see 2015, 51, 12977-12980 Chemical Communications or Nature Commun, 2014, 5, 3244). Few materials can produce this property. Here we built on previous observations that c-type lectins (carbohydrate binding proteins) had evolutionary relationships to AFPs, but by using non-homologous plant lectins. Interestingly, these only have activity in the presence of Ca2+, which is also required for sugar-binding, suggesting a relationship. Furthermore, we also show that a simple antibacterial peptide, Nisin A, also has ice inhibition activity, based on amphiphilicity. Whilst these were not as active as polymers we have previosly identified this provides a biological route to AFP mimetics, which offers many advantages.
Read the paper here.