In the diagnosis of disease, proteins are common biomarkers. These are typically detecting using antibodies which specifically target protein sequences, such as those used in lateral flow devices (LFDs). However, there is a challenge in that any given protein sequence can have many different post-translational modifications - phosphorylation, lipidation and many more including glycosylation - the addition of glycans. The presence of a particular protein (detected by antibodies) does not always indicate disease and the exact glycoform is an important parameter not detected by current biosensing strategies, requiring complicated methods or technologies such as mass spectrometry. In this work, we show a hybrid detection based on antibodies and lectins - glycan 'reading' proteins. We use the antibody on the surface of a biolayer interferometry sensor to first capture 'all proteins which match' the antibody, but they use lectin-coated gold nanoparticles as the signal generators, so that we only detect a single glycoform. We demonstrate this with prostate specific antigen (PSA), where the different glycoforms, not just protein concentration, are important markers of disease.

Read the paper here, published in Nanoscale Horizons

Discrimination between protein glycoforms using lectin-functionalised gold nanoparticles as signal enhancersLink opens in a new window

Cell culture enables the study of biological process and the discover of new drugs and biomaterials outside of the body. However, culturing cells in 2-D is not always predictive of what cells do in 3D (inside the body). There is a need to make 3D cell models (which are harder to prepare) to enable predictive screening to predict outcomes in the body, without (or before) resorting to animal models. In our latest work we have developed a method to cryopreserve spheroids - 3-D assemblies of cells which are more predictive of physiological outcomes than normal 2D monolayers. We achieved this using our macromolecular cryoprotectants which mitigate cold damage by mechanisms that traditional cryoprotective agents dont address. We show that liver-cell spheroids can be recovered in high yield, are healthy and respond to drugs (i.e. toxicity testing) the same as fresh spheroids.

This work is important, as spheroids are known to be more predictive than 2D cell monolayers but the barrier to researchers to use them is high, developing the techniques and handling of the cells. By developing this method to freeze them, the spheroids can be prepared, banked and easily shared as a frozen product. This work was conducted in collaboration with our Biotech spin-out Cryologyx Ltd.

Read the paper here

Cryopreservation of Liver-Cell Spheroids with Macromolecular CryoprotectantsLink opens in a new window

We have a major research interest in understanding, and deploying, ice binding protein mimetics. Whilst we have made huge progress with polymers which can slow the rate of ice growth, the question of how to make ice nucleate remains a challenge. Ice nucleating proteins form complex assemblies and isolated proteins are poor nucleators. To address this, we have synthesised dense bottlebrush polymers with poly(vinyl alcohol) side chains. These side chains are known to bind ice and when presented as very high molecular weight (100's of kg/mol) we show they can nucleate ice. This is the first report of a bottom-up designed polymeric nucleator which we can now use as a tool to probe ice nucleation.

Read the paper here

Poly(vinyl alcohol) molecular bottlebrushes nucleate iceLink opens in a new window

Our latest work, from Mchem student (now PhD at Birmingham) Julian has been published in RSC Advances. We have a long standing interest in using plasmonic (gold) nanoparticles in biosensing. For example, during COVID we used our nanoparticle platform to identify glycans which the spike protein binds to. One useful feature of gold nanoparticles is their colour change (red to blue) when they aggregate. We have developed technology to install glycans using polymeric tethers to the gold particles allowing 'easy' deciphering of if the glycans are binding their protein partners by simple colour changes. In this latest work we set out to make a 'recipe' that a new user can follow to let them use our system in their own lab. This involved finding the optimum size, polymer length and crucially concentration of the gold to minimise false positives/negatives. We hope this paper is useful to other users who are interested in this tool.

Read the work here

Polymer-Tethered Glyconanoparticle Colourimetric Biosensors for Lectin Binding: Structural and Experimental Parameters to Ensure a Robust OutputLink opens in a new window

We are not beginning to advertise our (fully funded) PhD openings for 2023 start. These span polymer chemistry, glycobiology, cryobiology and diagnostics. We apply these tools in important areas of sustainability, new healthcare materials and more.

More here

https://warwick.ac.uk/fac/sci/chemistry/research/gibson/gibsongroup/vacancies/Link opens in a new window

Nanoparticles have found widespread use in diagnostics and have been suggested for e.g. drug delivery. Chemists can now fine tune the nanoparticle surface to e.g target cell types. However, what a cell 'sees' is not what is made, but is the particle surface plus any proteins which adhere to it in blood - the protein corona. There has been extensive research into the proteins which make up the corona, but the glycans on these proteins have received less attention. In our latest work, we investigate the impact of the glycoprotein corona on how polymer-coated nanoparticles bind lectins. We show that serum proteins bring significant sialic acids to the particle surface. The impact of this, is that the particles can bind additional lectins (which were not intended) as well as those which are intended. Finally, we show that 'blocking' the surface does reduce the amount of protein, but sufficient glycans remain to cause off-target binding. These results will help guide the next generation of nanoparticle sensing and delivery agents.

Read the paper here:

Polymer-Tethered Glycosylated Gold Nanoparticles Recruit Sialylated Glycoproteins into their Protein Corona, Leading to Off-Target Lectin BindingLink opens in a new window

Most cell biology, biomaterials and associated research is conducted on cells attached to tissue culture plastic in multiwell plates - such as high throughput drug discovery and toxicity, to viral plaque assays. However, there is a disconnect that the cells are stored frozen in suspension, not in the format ‘ready to use’. This is because conventional cryoprotectants do not protect the cells when in monolayer format. The GibsonGroup, and UoW Spin-Out Cryologyx have worked together to solve this problem using macromolecular cryoprotectants. In this later paper, the team demonstrate reproducible and robust recovery of cell monolayers out of the freezer. This is shown for common cell lines, including HepG2 and Caco-2, commonly used in drug screening. This is a revolutionary technology as it shows researchers could stop wasting time culturing cells, and just order them, remove from freezer and within 24 hours begin data collection with no of the traditional culturing steps. Cryologyx are deploying these findings to commercialise assay ready cells, and trial plates are available!

Read the paper hereLink opens in a new window

The Gibson Group labs in Chemistry and The Medical School have been awarded with a Bronze LEAF award for the 2021/22 academic year.

Following a successful portfolio submission and inspection we were provided with the following feedback "The Gibson lab is a fantastic example of a lab that is working with the support of the PI to consider sustainability across every aspect of their work. During the audit it was great to hear that LEAF has encouraged lab users to implement some of the sustainability practices that have been discussed before but never implemented. There are some great examples of best practice, which could be shared with others outside of the lab, including the successful annual inventory check."

In recognition of our success at implementing environmentally friendly protocols, Caroline Biggs has been invited to speak the the University-Wide LEAF promotion and celebration event on 11th October.

Find out more about the LEAF initiative and how to get involved here https://warwick.ac.uk/sustainability/environment/gettinginvolved/sustainablelabs/