ORCID Profile
0000-0003-4875-4293
Current Organisation
University of Liverpool
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Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CC05909C
Abstract: A single maleimide was installed onto the self-assembled monolayer of gold nanoparticles by copper-free click chemistry. Simple covalent biofunctionalisation is demonstrated by coupling fibroblast growth factor 2 and an oligosaccharide in a 1 : 1 stoichiometry by thiol-Michael addition.
Publisher: Wiley
Date: 07-11-2022
Abstract: Infection of host cells by SARS‐CoV‐2 begins with recognition by the virus S (spike) protein of cell surface heparan sulfate (HS), tethering the virus to the extracellular matrix environment, and causing the subunit S1‐RBD to undergo a conformational change into the ‘open’ conformation. These two events promote the binding of S1‐RBD to the angiotensin converting enzyme 2 (ACE2) receptor, a preliminary step toward viral‐cell membrane fusion. Combining ligand‐based NMR spectroscopy with molecular dynamics, oligosaccharide analogues were used to explore the interactions between S1‐RBD of SARS CoV‐2 and HS, revealing several low‐specificity binding modes and previously unidentified potential sites for the binding of extended HS polysaccharide chains. The evidence for multiple binding modes also suggest that highly specific inhibitors will not be optimal against protein S but, rather, erse HS‐based structures, characterized by high affinity and including multi‐valent compounds, may be required.
Publisher: Elsevier BV
Date: 09-2006
Publisher: Oxford University Press (OUP)
Date: 24-08-2015
Abstract: Transforming growth factor-β1 (TGF-β1, Uniprot: P01137) is a heparin-binding protein that has been implicated in a number of physiological processes, including the initiation of chondrogenesis by human mesenchymal stem cells (hMSCs). Here, we identify the molecular features in the protein and in heparin required for binding and their effects on the potentiation of TGF-β1's activity on hMSCs. Using a proteomics "Protect and Label" approach, lysines K291, K304, K309, K315, K338, K373, K375 and K388 were identified as being directly involved in binding heparin (Data are available via ProteomeXchange with identifier PXD002772). Competition assays in an optical biosensor demonstrated that TGF-β1 does require N- and 6-O-sulfate groups for binding but that 2-O-sulfate groups are unlikely to underpin the interaction. Heparin-derived oligosaccharides as short as degree of polymerization (dp) 4 have a weak ability to compete for TGF-β1 binding to heparin, which increases with the length of the oligosaccharide to reach a maximum between dp18 and dp24. In cell-based assays, heparin, 2-O-, 6-O- and N-desulfated re-N-acetylated heparin and oligosaccharides 14-24 saccharides (dp14-24) in length all increased the phosphorylation of mothers against decapentaplegic homolog 2 (SMAD2) after 6 h of stimulation with TGF-β1. The results provide the structural basis for a model of heparin/heparan sulfate binding to TGF-β1 and demonstrate that the features in the polysaccharide required for binding are not identical to those required for sustaining the signaling by TGF-β1 in hMSCs.
Publisher: Future Medicine Ltd
Date: 11-2014
DOI: 10.2217/NNM.14.38
Abstract: Aim: To investigate interactions of gold nanoparticles with primary human lymphocytes and determine if the addition of a self-assembled monolayer of ‘mixed-matrix’ ligands influenced these interactions. Materials & methods: The effect of gold nanoparticles was measured by exposure to peripheral blood mononuclear cells (PBMCs) from healthy volunteers with subsequent examination of cell proliferation, cytokine secretion and CD4 + T-cell activation relative to controls. Results: Capped and as-synthesized gold nanoparticles augmented PBMC proliferation in response to phytohemagglutinin and this effect was greater for as-synthesized than for capped gold nanoparticles. Release of IL-10 and IFN-γ from PBMCs was increased and the effect was again more marked for as-synthesized than capped gold nanoparticles. Conclusion: This method provides an ex vivo approach for studying the interaction of nanoparticles with the human immune system. Further research is required to determine the specific mechanisms for reduction of immune activation seen here which could then be used to design a truly ‘stealth’ nanoparticle. Original submitted 11 October 2013 Revised submitted 30 January 2014
Publisher: American Chemical Society (ACS)
Date: 03-09-2009
DOI: 10.1021/NN9006994
Abstract: Understanding the dynamic fate and interactions of bioconjugated nanoparticles within living cells and organisms is a prerequisite for their use as in situ sensors or actuators. While recent research has provided indications on the effect of size, shape, and surface properties of nanoparticles on their internalization by living cells, the biochemical fate of the nanoparticles after internalization has been essentially unknown. Here we show that, upon internalization in a wide range of mammalian cells, biological molecules attached to the nanoparticles are degraded within the endosomal compartments through peptide cleavage by the protease cathepsin L. Importantly, using bioinformatics tools, we show that cathepsin L is able to cleave more than a third of the human proteome, indicating that this degradation process is likely to happen to most nanoparticles conjugated with peptides and proteins and cannot be ignored in the design of nanomaterials for intracellular applications. Preservation of the bioconjugates can be achieved by a combination of cathepsin inhibition and endosome disruption.
Publisher: The Royal Society
Date: 06-2015
DOI: 10.1098/RSOS.140454
Abstract: Raster image correlation spectroscopy (RICS) measures the diffusion of fluorescently labelled molecules from stacks of confocal microscopy images by analysing correlations within the image. RICS enables the observation of a greater and, thus, more representative area of a biological system as compared to other single molecule approaches. Photothermal microscopy of gold nanoparticles allows long-term imaging of the same labelled molecules without photobleaching. Here, we implement RICS analysis on a photothermal microscope. The imaging of single gold nanoparticles at pixel dwell times short enough for RICS (60 μs) with a piezo-driven photothermal heterodyne microscope is demonstrated (photothermal raster image correlation spectroscopy, PhRICS). As a proof of principle, PhRICS is used to measure the diffusion coefficient of gold nanoparticles in glycerol : water solutions. The diffusion coefficients of the nanoparticles measured by PhRICS are consistent with their size, determined by transmission electron microscopy. PhRICS was then used to probe the diffusion speed of gold nanoparticle-labelled fibroblast growth factor 2 (FGF2) bound to heparan sulfate in the pericellular matrix of live fibroblast cells. The data are consistent with previous single nanoparticle tracking studies of the diffusion of FGF2 on these cells. Importantly, the data reveal faster FGF2 movement, previously inaccessible by photothermal tracking, and suggest that inhomogeneity in the distribution of bound FGF2 is dynamic.
Publisher: Public Library of Science (PLoS)
Date: 17-07-2012
Publisher: Wiley
Date: 03-02-2015
Abstract: A non-membrane protein-based nanoparticle agent for the tracking of lipid rafts on live cells is produced by stoichiometric functionalization of gold nanoparticles with a previously characterized sphingolipid- and cell membrane microdomain-binding domain peptide (SBD). The SBD peptide is inserted in a self-assembled monolayer of peptidol and alkane thiol ethylene glycol, on gold nanoparticles surface. The stoichiometric functionalization of nanoparticles with the SBD peptide, essential for single molecule tracking, is achieved by means of non-affinity nanoparticle purification. The SBD-nanoparticles have remarkable long-term resistance to electrolyte-induced aggregation and ligand-exchange and have no detectable non-specific binding to live cells. Binding and diffusion of SBD-nanoparticles bound to the membrane of live cells is measured by real-time photothermal microscopy and shows the dynamics of sphingolipid-enriched microdomains on cells membrane, with evidence for clustering, splitting, and diffusion over time of the SBD-nanoparticle labeled membrane domains. The monofunctionalized SBD-nanoparticle is a promising targeting agent for the tracking of lipid rafts independently of their protein composition and the labelling requires no prior modification of the cells. This approach has potential for further functionalization of the particles to manipulate the organization of, or targeting to microdomains that control signaling events and thereby lead to novel diagnostics and therapeutics.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CH11429
Abstract: The importance of having nanoparticles that are soluble, stable, and that have no non-specific binding is often overlooked, but essential for their use in biology. This is particularly prominent with silver nanoparticles that are susceptible to the effects of aggregation and metal-surface reactivity. Here we use a combination of several small peptidols and short alkanethiol ethylene glycol ligands to develop a ligand shell that is reasonably resistant to ligand exchange and non-specific binding to groups common in biological molecules. The stability of the nanoparticles is not affected by the inclusion of a functional ligand, which is done in the same preparative step. The stoichiometry of the nanoparticles is controlled, such that monofunctional silver nanoparticles can be obtained. Two different sets of nanoparticles, functionalized with either Tris-nitrilotriacetic acid or a hexa-histidine peptide sequence, readily form dimers/oligomers, depending on their stoichiometry of functionalization.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for David Fernig.