I22-Small angle scattering & Diffraction
|
M.
Hassan Sk
,
S. M.
Clarke
,
M.
Woolley
,
A.
Osudare
,
S.
Agrawal
,
N.
Sharifi
,
D.
Eberl-Craske
,
R.
Lindsay
,
M. T. L.
Casford
,
A.
Smith
,
N.
Terrill
Diamond Proposal Number(s):
[23699, 28693, 32669]
Open Access
Abstract: In this study we have investigated the nucleation mechanism of ‘sweet’, CO2 corrosion scale in situ using synchrotron scattering under industrially relevant conditions (CO2 saturated brine, ultra-low oxygen (8–32 ppb), 80 °C, pH 6.8, open-circuit-potential (OCP)). Simultaneous small and wide-angle X-Ray Scattering (SAXS-WAXS) measurement allows the phase and state of the nucleating corrosion scale to be characterised as a function of both immersion time and location with respect to the metal/solution interface. The results indicate that a precursor amorphous phase is formed prior to the emergence of a crystalline iron carbonate scale.
|
Dec 2025
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Diamond Proposal Number(s):
[40520, 38927]
Open Access
Abstract: We employ a combined computational and experimental approach to systematically assess the hydrostatic properties of methanol–ethanol (MeOH–EtOH) mixtures of varying compositions, with the aim of evaluating their suitability as pressure-transmitting mediums (PTMs). PTMs are essential for enabling the characterization of materials properties at high pressure, perhaps most prominently in the context of diffraction measurements, to provide uniform compression and avoid strain on the sample. Molecular dynamics (MD) simulations indicate that the hydrostatic limit and several structural and dynamic properties of the widely used 4:1 MeOH–EtOH volume ratio do not exhibit any significant deviations from the monotonic trends observed as a function of MeOH content within the mixture. These findings are in agreement with X-ray pair distribution function measurements, which show no peculiar structural behaviour for the 4:1 composition. Experimental measurements of the hydrostatic limit confirm this result and demonstrate that, as previously reported, the role of ethanol is primarily to delay MeOH crystallization. However, we find that the same role can be fulfilled by other small molecules, such as propan-2-ol. Additional simulations of several MeOH–X binary mixtures suggest that these results might hold for a variety of similar mixtures. Thus, our findings indicate that the 4:1 ratio is neither peculiar nor optimal in terms of PTM performance; instead, its popularity seems to be mostly due to the influence of previous literature. Indeed, we find that the 9:1 MeOH–EtOH mixture is characterized by a hydrostatic limit which is superior (by nearly 1 GPa) to that observed for the 4:1 ratio. These findings offer a promising alternative PTM composition which is readily available, and pave the way towards future work aimed at the rational design of novel PTMs.
|
Dec 2025
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[31850]
Open Access
Abstract: To ensure safety, pharmaceuticals are rigorously tested for lipopolysaccharide (LPS) contamination, as this can trigger severe immune reactions in patients. Low Endotoxin Recovery (LER), describing the masking of spiked LPS controls in Limulus Amebocyte Lysate (LAL) assays, has been associated with the presence of chelating agents and surfactants in pharmaceutical formulations. The addition of excipients, such as Mg2+, have shown the ability to mitigate the effects of LER, however, inconsistencies in various studies regarding the influence of the excipients on LPS aggregate characteristics and LER occurrence hinder a clear understanding of the mechanisms underlying LER. In this study, dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) were employed to systematically assess the impact of chelating agents, surfactants, and divalent cations on the size and shape of LPS aggregates across various formulations. Our results indicate that surfactant-only formulations generally reduce LPS aggregate size, whereas chelating agent-only formulations do not. Notably, the smallest aggregates were observed when both chelating agents and surfactants were present, with the extent of size reduction being specific to the particular excipients used. Additionally, Mg2+ generally inhibited the excipients’ capacity to decrease aggregate size, most effectively in phosphate-containing samples. Despite these variations in size, the overall aggregate shape remained largely unchanged in all formulations. These findings suggest that LPS aggregate size or shape does not distinguish formulations causing LER; instead, factors such as the characteristics of the LPS aggregate surface in different formulations should be explored in the future.
|
Nov 2025
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[36130]
Open Access
Abstract: The initiation of allergic responses critically depends on the recognition of an allergenic epitope by the paratope of IgE antibodies. While previous structural studies have focused on recombinant fragments or engineered forms of IgE, the structure of full-length IgE in its native state remains poorly understood. In this study, we investigate the conformational changes of a native murine IgE (2F5), both in its free form and upon binding to the Hevea brasiliensis allergen profilin (Hev b 8). Small-angle X-ray scattering (SAXS) data reveal that unbound IgE adopts an extended conformation with open Fab arms. However, when it binds to profilin, it transitions to a more compact arrangement characterized by closer proximity of the arms. Molecular dynamics (MD) simulations of the Fab region further identified conformational rearrangements upon allergen binding, including a twisting motion and partial disruption of interactions between the naturally paired heavy and light chains. These findings indicate that there may be allosteric communication between Fab and Fc regions, even in the absence of a hinge region, which is not present in IgE. Overall, this study provides valuable insights into the dynamic structural properties of native IgE and enhances our understanding of the molecular mechanisms underlying allergen recognition.
|
Nov 2025
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[38168]
Open Access
Abstract: Cyclophilins (Cyps) are ubiquitous cytosolic proteins with peptidyl-prolyl cis-trans isomerase (PPIase) activity and the ability to bind the immunosuppressant cyclosporin A (CsA). The genome of Toxoplasma gondii, the parasite responsible for toxoplasmosis, encodes multiple putative Cyps, whose specific functions remain largely unexplored.
Here, we characterize TgCyp21, a predicted Cyp from T. gondii. TgCyp21 displays PPIase activity and is inhibited by CsA in vitro. Importantly, its activity decreases markedly under oxidizing conditions but is partially restored by reducing agents, including dithiothreitol (DTT) and the parasite endogenous thioredoxin (TgTrx). TgCyp21 contains four cysteines, with Cys87 and Cys141 predicted to be spatially close based on structural modeling. Substitution of both residues significantly reduced PPIase activity, with Cys87 emerging as the main contributor to this loss. Structural modeling further indicates that Cys87 and Cys141 are suitably oriented to interact with the conserved active-site cysteines of TgTrx. This interaction is supported experimentally by mixed disulfide trapping, which identifies a stable disulfide-linked intermediate between TgCyp21 and TgTrx, consistent with a thiol-disulfide exchange mechanism. Small-angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR) spectroscopy further confirm the formation of the complex.
Taken together, our data indicate that TgCyp21 behaves in vitro as a redox-responsive Cyp and a substrate for Trx, suggesting a potential involvement in Trx-mediated redox processes in T. gondii.
|
Nov 2025
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[31378]
Open Access
Abstract: Amphiphilic compounds, such as phospholipids or surface-active substances, are present in biological systems and can be part of pharmaceutical formulations. As a consequence, all pharmaceutically active ingredients will encounter amphiphilic compounds, either in the formulation or after administration. With the growing interest in peptide-based pharmaceuticals, there is a need to enhance the understanding of the interactions between peptides and amphiphilic compounds.
In this particular study, we have chosen to study mixtures of the comparatively small cyclical octapeptide lanreotide and the conventional anionic surfactant sodium dodecylsulfate (SDS). This was done by examining the self-assembly structures formed in lanreotide-SDS mixtures using light scattering and small-angle X-ray scattering (SAXS).
Above the critical micelle concentration (cmc) of SDS, the large excess of SDS could solubilize all lanreotide and form small micelles with lanreotide attached to the interface. Upon dilution to concentrations below the cmc of SDS, a suspension with dispersed solid nanoparticles is formed. The solid nanoparticles grow in size with decreasing concentration and, eventually, precipitate. The precipitated material is arranged in a liquid crystalline micellar phase, consisting of small close-packed SDS micelles with peptide adsorbed at the interface.
We were able to conclude that lanreotide does not form mixed micelles with SDS, indicating that it lacks the amphiphilic properties required to integrate fully with SDS behaving as a cosurfactant. In contrast, lanreotide attaches to the interface of SDS micelles, resembling the interactions of polymers, proteins, and nucleic acids with surfactants.
|
Nov 2025
|
|
B21-High Throughput SAXS
I04-Macromolecular Crystallography
|
Diamond Proposal Number(s):
[32787, 25301]
Open Access
Abstract: Listeria monocytogenes is the causative agent of Listeriosis, a serious foodborne illness that primarily affects pregnant women, new-borns, the elderly, and immunocompromised individuals. L. monocytogenes secretes proteins that bind and degrade chitin, a linear polysaccharide formed of β1,4-linked N-acetylglucosamine residues, and although humans do not produce chitin, these enzymes act as virulence factors that promote bacterial growth during host infection. The chitinase ChiA is a major contributor to virulence, and it can modulate host immunity through downregulating the expression of host inducible nitric oxide synthase (iNOS), although this precise mechanism has yet to be determined. Here we present the X-ray crystal structure of L. monocytogenes ChiA at 1.95 Å resolution, complemented by solution small angle X-ray scattering analysis and molecular dynamics simulations. Our comparative analyses reveal structural conservation with homologous bacterial chitinases and highlight potential alternative ligand-binding sites beyond the canonical chitin-binding channel. Molecular dynamics simulations of an N-glycopeptide model demonstrate stable interactions between LmChiA and the mannose-rich N-glycan core near these putative sites. These findings suggest that LmChiA may interact with branched host glycans rather than exclusively processing chitin-derived substrates, and this provides a potential explanation for its role in modulating host immune responses.
|
Oct 2025
|
|
I21-Resonant Inelastic X-ray Scattering (RIXS)
|
Diamond Proposal Number(s):
[38040]
Open Access
Abstract: Altermagnets, a unique class of magnetic materials that combines features of both ferromagnets and antiferromagnets, have garnered attention for their potential in spintronics and magnonics. While the electronic properties of altermagnets have been well studied, characterizing their magnon excitations is essential for fully understanding their behavior and enabling practical device applications. In this work, we introduce a measurement protocol combining resonant inelastic X-ray scattering with circular polarization and azimuthal scanning to probe the chiral nature of the altermagnetic split magnon modes in CrSb. This approach circumvents the challenges posed by domain averaging in macroscopic samples, allowing for precise measurements of the polarization and energy of the magnons in individual antiferromagnetic domains. Our findings demonstrate a pronounced circular dichroism in the magnon peaks, with an azimuthal dependence that is consistent with the theoretical predictions and the g-wave symmetry. By establishing a reliable and accessible method for probing altermagnetic magnons, this work opens new avenues for fundamental studies of these collective excitations and for developing next-generation magnonic device applications.
|
Oct 2025
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[35585]
Open Access
Abstract: Peptide-based nanogels (NGs) represent a cutting-edge class of nanoscale drug delivery systems. Due to their structural properties, NGs platforms can encapsulate and protect therapeutic agents (e.g. peptides, proteins, and nucleic acids), while allowing for controlled and stimuli-responsive release. These pharmacokinetic and pharmacodynamic features can be specifically tuned by including peptide functional elements as NG components. This study explores the formulation, decoration strategies, and structural properties of NGs derived from mixed hydrogel (HG) matrices of Fmoc-diphenylalanine (Fmoc-FF) with cationic amphiphilic peptides (CAPs). CAPs, composed by cationic hexapeptide (GK)3 sequence decorated at its N-terminus with alkyl chain, were found able to confer a net positive charge to Fmoc-FF NGs. Fmoc-FF/C16-(GK)3 and Fmoc-FF/C18-(GK)3 NGs were obtained using polysorbate 80 (TWEEN 80) and sorbitane monooleate 80 (SPAN 80) as colloidal stabilizing surfactants and characterized in terms of size, secondary structure, superficial charge and shelf stability by Dynamic Light Scattering (DLS), Circular Dichroism (CD), Fourier Transform Infrared (FT-IR) and Small-Angle X-ray Scattering (SAXS) technique. Different formulative routes were used and mutually compared to encapsulate or adsorb AlexaFluor 430 (succinimidyl ester), used as model of an anionic, pharmaceutical agent. In vitro experiments demonstrated good cytocompatibility of these systems and the release of AlexaFluor 430 was also evaluated.
|
Oct 2025
|
|
labSAXS-Offline SAXS and Sample Environment Development
|
Mona
Semsarilar
,
Martin J.
Greenall
,
Alex H.
Balzer
,
Amit Kumar
Sarkar
,
Chaimaa
Gomri
,
Belkacem Tarek
Benkhaled
,
Anke-Lisa
Höhme
,
Martin
Held
,
Volker
Abetz
,
Helena J.
Hutchins-Crawford
,
Georgia L.
Maitland
,
Anisha
Patel
,
Thomas H.
Epps
,
Paul D.
Topham
,
Matthew J.
Derry
Diamond Proposal Number(s):
[29567, 31903]
Open Access
Abstract: We report the combined experimental and theoretical study of the bulk self-assembly behavior of polystyrene-block-poly(2,3,4,5,6-pentafluorostyrene) diblock copolymers. These block copolymers were designed to create highly antagonistic blocks (with a high Flory–Huggins interaction parameter, χ) with minimum disruption to the molecular construct (i.e., only replacing five hydrogen atoms with five fluorine atoms). A large library of diblock copolymers (41 samples) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization to map out a major portion of the phase space. All block copolymers exhibited narrow molecular weight distributions with dispersity (D) values between 1.07 and 1.32, and subsequent thermal annealing revealed phase separation into well-defined nanoscale morphologies depending on their molecular composition, as determined from small-angle X-ray scattering and transmission electron microscopy analyses, with an experimental phase diagram being constructed. The χ value at 25 °C for this block copolymer was estimated to be 0.2 using strong segregation theory, based on trends in phase-separated domain spacing and interfacial width. When applying theoretical approaches, the majority of the domain spacing data trends were captured by a coil–coil diblock copolymer model; however, a better fit to the data for samples with shorter fluorinated blocks was obtained with a rod–coil model, indicating that the chains in these fluorinated blocks likely have a higher inherent stiffness and were thus rod-like. This observation demonstrates that, due to the very high value of χ, a transition from coil–coil to rod–coil behavior can be obtained purely by reducing the length of the stiffer of the two blocks and without varying temperature or the chemical composition of the polymers. This work showcases the presence of strong microphase separation within AB diblock copolymers despite the relatively similar chemical composition of the constituent “A” and “B” units, with a clear transition from rod–coil to coil–coil segregation behavior.
|
Oct 2025
|
|
