
Charley SchaeferUniversity of Leeds
Charley Schaefer
PhD
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44
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Introduction
Publications
Publications (44)
The condensation of Rubisco holoenzymes and linker proteins into “pyrenoids,” a crucial supercharger of photosynthesis in algae, is qualitatively understood in terms of “sticker-and-spacer” theory. We derive semianalytical partition sums for small Rubisco-linker aggregates, which enable the calculation of both dilute-phase titration curves and dime...
Membraneless droplets formed through liquid-liquid phase separation (LLPS) play a crucial role in mRNA storage, enabling organisms to swiftly respond to environmental changes. However, the mechanisms underlying mRNA integration and protection within droplets remain unclear. Here, we unravel the role of bacterial aggresomes as stress granules (SGs)...
Biopolymer topology is critical for determining interactions inside cell environments, exemplified by DNA where its response to mechanical perturbation is as important as biochemical properties to its cellular roles. The dynamic structures of chiral biopolymers exhibit complex dependence with extension and torsion, however the physical mechanisms u...
Biopolymer topology is critical for determining interactions inside cell environments, exemplified by DNA where its response to mechanical perturbation is as important as biochemical properties to its cellular roles. The dynamic structures of chiral biopolymers exhibit complex dependence with extension and torsion, however the physical mechanisms u...
Bio-polymer networks are ubiquitous in nature and fulfil unique mechanical and biological functionalities that sensitively rely on the mesoscopic structure of the network. Understanding how these structures are encoded for by the bio-macromolecular building blocks would open up a powerful means to design novel soft materials, but remains hampered b...
A major pathogenic hallmark of Alzheimer's disease is the presence of neurotoxic plaques composed of amyloid beta (Aβ) peptides in patients' brains. The pathway of plaque formation remains elusive, though some clues appear to lie in the dominant presence of Aβ 1 − 42 in these plaques despite Aβ 1−40 making up approximately 90% of the Aβ pool. We hy...
A major pathogenic hallmark of Alzheimer’s disease is the presence of neurotoxic plaques composed of amyloid beta (Aβ) peptides in patients’ brains. The pathway of plaque formation remains elusive, though some clues appear to lie in the dominant presence of Aβ1-42 in these plaques despite Aβ1-40 making up approximately 90% of the Aβ pool. We hypoth...
The solubilization of lipid membranes by Tween-20 is crucial for a number of biotechnological applications, but the mechanistic details remain elusive. Evidence from ensemble assays supports a solubilization model that encompasses surfactant association with the membrane and the release of mixed micelles to solution, but whether this process also i...
A major pathogenic hallmark of Alzheimer's disease is the presence of neurotoxic plaques composed of amyloid beta (Aβ) peptides in patients' brains. The pathway of plaque formation remains elusive, though some clues appear to lie in the dominant presence of Aβ1−42 in these plaques despite Aβ1−40 making up approximately 90% of the Aβ pool. We hypoth...
Silk is a semidilute solution of randomly coiled associating polypeptide chains that crystallize following the stretch-induced disruption, in the strong extensional flow of extrusion, of the solvation shell around their amino acids. We propose that natural silk spinning exploits both the exponentially broad stretch distribution generated by associa...
The interaction of Tween-20 with lipid membranes is crucial for a number of biotechnological applications including viral inactivation and membrane protein extraction, but the underlying mechanistic details have remained elusive. Evidence from ensemble assays supports a global model of Tween-20 induced membrane disruption that broadly encompasses a...
Silk is a semi-dilute solution of randomly coiled associating polypeptide chains that crystallise following the stretch-induced disruption, in the strong extensional flow of extrusion, of the sol-vation shell around their amino acids. We propose that natural silk spinning exploits both the exponentially-broad stretch-distribution generated by assoc...
Liquid-liquid phase separation is emerging as a crucial phenomenon in several fundamental cell processes. A range of eukaryotic systems exhibit liquid condensates. However, their function in bacteria, which, in general, lack membrane-bound compartments, remains less clear. Here, we used high-resolution optical microscopy to observe single bacterial...
Liquid-liquid phase separation is emerging as a crucial phenomenon in several fundamental cell processes. A range of eukaryotic systems exhibit liquid condensates. However, their function in bacteria, which in general lack membrane-bound compartments, remains less clear. Here, we used high-resolution optical microscopy to observe single bacterial a...
The flow-induced self-assembly of entangled Bombyx mori silk proteins is hypothesised to be aided by the ‘registration’ of aligned protein chains using intermolecularly interacting ‘sticky’ patches. This suggests that upon chain alignment, a hierarchical network forms that collectively stretches and induces nucleation in a precisely controlled way....
We present a tube model for the Brownian dynamics of associating polymers in extensional flow. In linear response, the model confirms the analytical predictions for the sticky diffusivity by Leibler-Rubinstein-Colby theory. Although a single-mode Doi-Edwards-Marrucci-Grizzuti approximation accurately describes the transient stretching of the polyme...
We present a tube model for the Brownian dynamics of associating polymers in extensional flow. In linear response, the model confirms the analytical predictions for the sticky diffusivity by Leibler- Rubinstein-Colby theory. Although a single-mode DEMG approximation accurately describes the transient stretching of the polymers above a 'sticky' Weis...
Silk is one of the most intriguing examples of biomolecular self-assembly, yet little is understood of molecular mechanisms behind the flow behavior generating these complex high-performance fibers. This work applies the polymer physics of entangled solution rheology to present a first microphysical understanding of silk in the linear viscoelastic...
We use Bond Fluctuation Model simulations to theoretically address three phenomena related to the liquid-liquid phase separation of intrinsically disordered proteins (IDPs): i. The influence of the coarse-grained protein sequence (i.e., location of hydrophilic and hydrophobic patches, as well as functional regions that can form (multivalent) interm...
https://pubs.rsc.org/en/content/articlepdf/2019/sm/c9sm01344j
Spontaneous liquid-liquid phase separation is commonly understood in terms of phenomenological mean-field theories. These theories correctly predict the structural features of the fluid at sufficiently long time scales and wavelengths. However, these conditions are not met in various ex...
Spontaneous liquid-liquid phase separation is commonly understood in terms of phenomenological mean-field theories. These theories correctly predict the structural features of the fluid at sufficiently long time scales and wavelengths. However, these conditions are not met in various examples in biology and materials science where the mixture is sl...
Although ternary solar cells (TSCs) offer a cost‐effective prospect to expand the absorption bandwidth of organic solar cells, only few TSCs have succeeded in surpassing the performance of binary solar cells (BSCs) primarily due to the complicated morphology of the ternary blends. Here, the key factors that create and limit the morphology and perfo...
Cover page for "Ligand-regulated oligomerisation of allosterically interacting proteins", Soft Matter, 2018, 14, 6961, DOI:10.1039/c8sm00943k
The binding of ligands to distinct sites at proteins or at protein clusters is often cooperative or anti- cooperative due to allosteric signalling between those sites. The allostery is usually attributed to a configurational change of the proteins from a relaxed to a configurationally different tense state. Alternatively, as originally proposed by...
Using the simple ‘allosteron’ model, we show that it is possible, in principle, to elicit pathways by which fluctuation allostery affects self-assembly of protein complexes. We treat the cases of (i) protein fibrils and nucleation, (ii) n-mer protein complexes, and (iii) weakly attractive allosteric interactions in protein-like soft nanoscale objec...
Casting Dispersions Symposium (London, 26 March 2018).
The surface composition of solvent-cast polymer composites or colloidal dispersions is determined by an interplay between the dynamics of solvent evaporation and by the thermodynamics of the constituents. The poster discusses this interplay, as well as the role of phase separation during proces...
Fluids with spatial density variations of single or mixed molecules play a key role in biophysics, soft matter, and materials science. The fluid structures usually form via spinodal decomposition or nucleation following an instantaneous destabilization of the initially disordered fluid. However, in practice, an instantaneous quench is often not via...
Fluids with spatial density variations of single or mixed molecules play a key role in biophysics,
soft matter and materials science. The fluid structures usually form via spinodal decomposition
or nucleation following an instantaneous destabilisation of the initially disordered fluid. However,
in practice an instantaneous quench is often not viabl...
http://pubs.acs.org/doi/ipdf/10.1021/acs.macromol.6b00537
Solution-cast, thin-film polymer composites find a wide range of applications, such as in the photoactive layer of organic solar cells. The performance of this layer crucially relies on its phase-separated morphology. Efficient charge-carrier extraction requires each of the components to pre...
The performance of polymer‒fullerene bulk heterojunction (BHJ) solar cells is highly affected by the morphology of the blend film. Though the structure of BHJ morphology is well-understood, the relationship between relevant material interactions and BHJ morphology evolutions are poorly understood and seldom explored. In this report, we discuss the...
We theoretically study the impact of solvent evaporation on the dynamics of isothermal phase separation of ternary polymer solutions in thin films. In the early stages we obtain a spinodal length scale that decreases with time under the influence of ongoing evaporation. After that rapid demixing occurs at a well-defined lag time, a morphology emerg...
This chapter focuses on modelling the spinodal decomposition of solution processed polymer:PCBM blends under evaporative conditions. This mode of phase separation has been experimentally observed for a wide range of polymer:PCBM blends, especially in the absence of co-solvents. Dry-film morphologies characteristically comprise droplet-shaped PCBM-r...
The photoactive layer of polymer solar cells is commonly processed from a four-component solution, containing a semiconducting polymer and a fullerene derivative dissolved in a solvent-cosolvent mixture. The nanoscale dimensions of the polymer-fullerene morphology that is formed upon drying determines the solar cell performance, but the fundamental...
The morphology of solution-cast, phase-separated polymers becomes finer with increasing solvent evaporation rate. We address this observation theoretically for a model polymer where demixing is induced by steady solvent evaporation. In contrast to what is the case for a classical, thermal quench involving immiscible blends, the spinodal instability...
The morphology of solution-cast, phase-separated polymers becomes finer with increasing solvent evaporation rate. We address this observation theoretically for a model polymer where demixing is induced by steady solvent evaporation. In contrast to what is the case for a classical, thermal quench involving immiscible blends, the spinodal instability...
Understanding of stationary charge transport in disordered organic
semiconductors has matured during recent years. However, charge-carrier
relaxation in nonstationary situations is still poorly understood. Such
relaxation can be studied in dark injection experiments, in which the
bias applied over an unilluminated organic semiconductor device is
ab...
We have developed a method to couple kinetic Monte Carlo simulations of surface reactions at a molecular scale to transport equations at a macroscopic scale. This method is applicable to steady state reactors. We use a finite difference upwinding scheme and a gap-tooth scheme to efficiently use a limited amount of kinetic Monte Carlo simulations. I...
The influence of the ratio between poor and good solvent on the stability and dynamics of supramolecular polymers is studied via a combination of experiments and simulations. Step-wise addition of good solvent to supramolecular polymers assembled via a cooperative (nucleated) growth mechanism results in complete disassembly at a critical good/poor...
In a combined experimental and theoretical approach, we investigate the supramolecular polymerization of ionic discotic amphiphiles into nanorods of varying mean length, depending on the temperature and ionic strength of the buffered aqueous solution. Invoking a nucleated supramolecular polymerization model that explicitly deals with the effects of...