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
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[30763]
Abstract: Extracellular polysaccharides exhibit a broad range of biological activities, among which antibiofilm activity is of particular interest due to the growing clinical importance of biofilm-related infections. Psychrobacter sp. TAE2020, a marine Gram-negative bacterium, produces a molecular complex named CATASAN, endowed with antibiofilm properties. The aim of this study is the identification and structural characterisation of the polysaccharidic component of the CATASAN complex. Moreover, the interest was in finding the structural features possibly responsible for the anti-biofilm and emulsifying activities. Here, it has been demonstrated that the polysaccharide within the CATASAN complex corresponds to the capsular polysaccharide produced by Psychrobacter sp. TAE2020. The detailed primary structure of this CPS is here reported, which is composed of a tetrasaccharide repeating unit containing two residues of α-D-galactosamine, one residue of α-D-2,4-diacetamido-2,4,6-trideoxy-α-glucopyranose, and the unusual α-L-gulosamine. The physical properties of the CPS, such as its ability to adhere to hydrophobic surfaces and exhibit emulsifying activity, suggest that this polymer is a promising candidate for alternative anti-infective applications in clinical settings.
|
Sep 2025
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Diamond Proposal Number(s):
[37860]
Open Access
Abstract: Supramolecular deep eutectic solvents (SUPRADESs), formed by combining cyclodextrins (CDs) with hydrogen bond donors, enhance solvation efficiency while retaining CD inclusion capabilities. This study presents the first detailed structural analysis of a SUPRADES composed of β-cyclodextrin (β-CD) and lactic acid (LA) (1:30 M ratio) using Molecular Dynamics simulations and X-ray scattering. Results reveal a well-dispersed system where LA molecules form stabilizing sheaths around isolated β-CDs, preventing coalescence through optimized hydrogen bonding and dispersive interactions. The SUPRADES significantly improved solubilisation and retention of water-insoluble trans-anethole (AN), demonstrating strong absorption capacity. While β-CD encapsulation of AN was limited, 2D ROESY NMR confirmed inclusion complex formation. These findings highlight the SUPRADES's unique microstructure and its potential as a sustainable, eco-friendly solvent for volatile organic compound (VOC) applications, offering insights for future green solvent design.
|
May 2025
|
|
I22-Small angle scattering & Diffraction
|
Diamond Proposal Number(s):
[33596]
Open Access
Abstract: We study the conformational, conductometric and rheological properties of semiflexible polyelectrolyte carboxymethyl cellulose in mixtures of water and three non-solvents (ethanol, isopropanol and acetone). Small angle x-ray scattering measurements of the correlation length reveal that the local conformation of the carboxymethyl chain is unchanged by the presence of a non-solvent, even for solutions not far from the phase boundary. Rheological measurements confirm the invariance of the correlation length upon non-solvent addition. Conductivity measurements show that as the non-solvent content is increased, the fraction of condensed counterions increases, presumably due to the lowering of the dielectric constant of the solvent media. These results therefore show that under room temperature and pressure, the conformation of polyelectrolyte chains is independent of the effective charge fraction of the backbone. We suggest this occurs because the bare Kuhn length () is much larger than electrostatic blob size ().
|
May 2024
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[15705]
Abstract: Carbohydrate-active enzymes from the glycoside hydrolase family 9 (GH9) play a key role in processing lignocellulosic biomass. Although the structural features of some GH9 enzymes are known, the molecular mechanisms that drive their interactions with cellulosic substrates remain unclear. To investigate the molecular mechanisms that the two-domain Bacillus licheniformis BlCel9A enzyme utilizes to depolymerize cellulosic substrates, we used a combination of biochemical assays, X-ray crystallography, small-angle X-ray scattering, and molecular dynamics simulations. The results reveal that BlCel9A breaks down cellulosic substrates, releasing cellobiose and glucose as the major products, but is highly inefficient in cleaving oligosaccharides shorter than cellotetraose. In addition, fungal lytic polysaccharide oxygenase (LPMO) TtLPMO9H enhances depolymerization of crystalline cellulose by BlCel9A, while exhibiting minimal impact on amorphous cellulose. The crystal structures of BlCel9A in both apo form and bound to cellotriose and cellohexaose were elucidated, unveiling the interactions of BlCel9A with the ligands and their contribution to substrate binding and products release. MD simulation analysis reveals that BlCel9A exhibits higher interdomain flexibility under acidic conditions, and SAXS experiments indicate that the enzyme flexibility is induced by pH and/or temperature. Our findings provide new insights into BlCel9A substrate specificity and binding, and synergy with the LPMOs.
|
Jan 2024
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[26835]
Open Access
Abstract: Weak polyelectrolytes (WPEs) are responsive materials used as active charge regulators in a variety of applications, including controlled release and drug delivery in crowded bio-related and synthetic environments. In these environments, high concentrations of solvated molecules, nanostructures, and molecular assemblies are ubiquitous. Here, we investigated the effect of high concentrations of non-adsorbing, short chains of poly(vinyl alcohol), PVA, and colloids dispersed by the very same polymers on charge regulation (CR) of poly(acrylic acid), PAA. PVA does not interact with PAA (throughout the full pH range) and thus can be used to examine the role of non-specific (entropic) interactions in polymer-rich environments. Titration experiments of PAA (mainly 100 kDa in dilute solutions, no added salt) were carried out in high concentrations of PVA (13–23 kDa, 5–15 wt%) and dispersions of carbon black (CB) decorated by the same PVA (CB-PVA, 0.2–1 wt%). The calculated equilibrium constant (and pKa
p
K
a
) was up-shifted in PVA solutions by up to ~0.9 units and down-shifted in CB-PVA dispersions by ~0.4 units. Thus, while solvated PVA chains increase the charging of the PAA chains, as compared to PAA in water, CB-PVA particles reduce PAA charging. To investigate the origins of the effect, we analyzed the mixtures using small-angle X-ray scattering (SAXS) and cryo-TEM imaging. The scattering experiments revealed re-organization of the PAA chains in the presence of the solvated PVA but not in the CB-PVA dispersions. These observations clearly indicate that the acid–base equilibrium and the degree of ionization of PAA in crowded liquid environments is affected by the concentration, size, and geometry of seemingly non-interacting additives, probably due to depletion and excluded volume interactions. Thus, entropic effects that do not depend on specific interactions should be taken into consideration when designing functional materials in complex fluid environments.
|
Feb 2023
|
|
I22-Small angle scattering & Diffraction
|
Diamond Proposal Number(s):
[15246, 15478]
Open Access
Abstract: The current work investigates the effect of the addition of graphene nanoplatelets (GNPs) and graphene oxide (GO) to high hard-segment polyurethane (75% HS) on its thermal, morphological, and mechanical properties. Polyurethane (PU) and its nanocomposites were prepared with different ratios of GNP and GO (0.25, 0.5, and 0.75 wt. %). A thermal stability analysis demonstrated an enhancement in the thermal stability of PU with GNP and GO incorporated compared to pure PU. Differential Scanning Calorimetry (DSC) showed that both GNP and GO act as heterogeneous nucleation agents within a PU matrix, leading to an increase in the crystallinity of PU. The uniform dispersion and distribution of GNP and GO flakes in the PU matrix were confirmed by SEM and TEM. In terms of the mechanical properties of the PU nanocomposites, it was found that the interaction between PU and GO was better than that of GNP due to the functional groups on the GO’s surface. This leads to a significant increase in tensile strength for 0.5 wt. % GNP and GO compared with pure PU. This can be attributed to interfacial interaction between the GO and PU chains, resulting in an improvement in stress transferring from the matrix to the filler and vice versa. This work sheds light on the understanding of the interactions between graphene-based fillers and their influence on the mechanical properties of PU nanocomposites.
|
Oct 2022
|
|
I22-Small angle scattering & Diffraction
|
Diamond Proposal Number(s):
[22659]
Abstract: A multi-analytical study was performed to analyse the effect of bacterial cellulose (BCF) on the self-association of starches with different amylose content (wheat, waxy-maize), assessing macrostructural properties (rheology, gel strength) and some nano and sub-nano level features (small and wide-angle X-ray scattering). Although pasting viscosities and G′ were significantly increased by BCF in both starches, cellulose did not seem to promote the self-association of amylose in short-range retrogradation. A less elastic structure was reflected by a 2–3-fold increase in loss factor (G″/G′) at the highest BCF concentration tested. This behavior agreed with the nano and sub-nano characterisation of the samples, which showed loss of starch lamellarity and incomplete full recovery of an ordered structure after storage at 4 °C for 24 h. The gel strength data could be explained by the contribution of BCF to the mechanical response of the sample. The information gained in this work is relevant for tuning the structure of tailored starch-cellulose composites.
|
Jul 2022
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[23804]
Open Access
Abstract: Zr-based oxoclusters MxOy(OR)w(OOR’)z are promising catalysts for the activation of hydrogen peroxide. However, they need to be integrated into suitable matrices to increase their hydrolytic stability and allow for their recovery after use. Polymeric materials can be successfully employed for this aim, since they modify the properties of the resulting hybrid materials, in terms of polarity and chemical affinity for the substrates, improving the catalytic activity. Herein, we report the synthesis of different acrylic polymers based on various co-monomers (methyl methacrylate (MMA), 2,2,2-trifluoroethylmethacrylate (TFMA) and 3-methacryloxypropyltrimethoxylsilane (MAPTMS)) covalently cross-linked by a Zr4-based oxocluster, whose composition was tuned to optimise the catalytic oxidation of methyl p-tolyl sulphide. To assess their properties and stability, the materials were characterised via Fourier Transform Infrared (FT-IR) and Raman spectroscopies, Thermogravimetric Analysis (TGA), Solid-State NMR (SS-NMR) and X-Ray Absorption Spectroscopies XAS, before and after catalytic turnover.
|
Oct 2021
|
|
B21-High Throughput SAXS
|
Diamond Proposal Number(s):
[26698]
Open Access
Abstract: Ciprofibrate (CIP) is a highly lipophilic and poorly water-soluble drug, typically used for dyslipidemia treatment. Although it is already commercialized in capsules, no previous studies report its solid-state structure; thus, information about the correlation with its physicochemical properties lacking. In parallel, recent studies have led to the improvement of drug administration, including encapsulation in polymeric nanoparticles (NPs). Here, we present CIP’s crystal structure determined by PDRX data. We also propose an encapsulation method for CIP in micelles produced from Pluronic P123/F127 and PEO-b-PCL, aiming to improve its solubility, hydrophilicity, and delivery. We determined the NPs’ physicochemical properties by DLS, SLS, ELS, and SAXS and the loaded drug amount by UV-Vis spectroscopy. Micelles showed sizes around 10–20 nm for Pluronic and 35–45 nm for the PEO-b-PCL NPs with slightly negative surface charge and successful CIP loading, especially for the latter; a substantial reduction in ζ-potential may be evidenced. For Pluronic nanoparticles, we scanned different conditions for the CIP loading, and its encapsulation efficiency was reduced while the drug content increased in the nanoprecipitation protocol. We also performed in vitro release experiments; results demonstrate that probe release is driven by Fickian diffusion for the Pluronic NPs and a zero-order model for PEO-b-PCL NPs.
|
Sep 2021
|
|
