15 research outputs found
Bottom-Up Cubosome Synthesis Without Organic Solvents
This dataset contains processed SAXS data for mixtures of phytantriol with different diluents, and also following bottom-up synthesis of cubosomes. This data was collected to demonstrate the phase formations of phytantriol under different conditions.SAXS data was collected on an Anton-Parr SAXSpoint 2.0.SAXS data was collected on an Anton-Parr SAXSpoint 2.0, using an SDD of 556.9mm. The instrument is known to have a single dead pixel which sometimes results in an anomolous single-point peak
Structural and chemical heterogeneity in ancient glass probed using gas overcondensation, X-ray tomography, and solid-state NMR
Rare ancient glasses have complex, multi-scale structures requiring more sophisticated and non-destructive pore characterisation techniques than usual. Homotattic patch models for nitrogen adsorption gave better fits to the isotherm data, more accurate void space descriptors, and also greater understanding of the underlying physical factors affecting adsorption, than standard BET. These homotattic patch models revealed the critical role of iron impurities in determining adsorption behaviour. Non-destructive sodium-23 NMR relaxometry validated the homotattic patch model for some natron glasses, and, in turn, was validated using multiple quantum magic-angle spinning (MQMAS) 23Na NMR. X-ray tomography images of the glasses showed the presence of large macroporous bubbles, while FEG-SEM revealed nanopores within the glass matrix. A newly-developed, gas overcondensation technique, suitable for small amounts of low porosity material, assessed the inter-relationship between the disparate levels in this hierarchical porosity. This technique demonstrated that the nanoporosity did not form a âcoronaâ around the bubbles, due to leaching from the glass, as initially supposed from tomography data, but was completely disconnected, and, thus, is probably associated with glass alkalinity. Gas overcondensation is demonstrated as a non-destructive alternative to mercury porosimetry for probing multi-scale porosity in rare artefacts
Microstructural, thermal, crystallization, and water absorption properties of films prepared from never-dried and freeze-dried cellulose nanocrystals
In this paper, the microstructural, optical, thermal, crystallization, and water absorption properties of films prepared from never-dried (ND) and freeze-dried (FD) cellulose nanocrystals (CNCs) are reported. Morphology of the ND CNCs reveals a needle-like structure, while after freeze-drying, they show a flake-like morphology. Microstructural analysis of ND and FD CNCs are further studied via small angle X-ray scattering to probe interactions. ND CNCs yield a transparent film with a low surface roughness (14 ± 4 nm), while the FD CNC film evidence a significant reduction of their transparency due to their higher surface roughness (134 ± 20 nm). Although Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy analyses reveal no chemical change occurs during the freeze-drying process, yet a more intense thermal degradation profile is observed for FD CNC film, probably due to the higher oxygen ingress within the gaps created between the stacked flakes. This, in turn, results in a greater loss of crystallinity at a higher temperature (300 °C) compared to the ND CNC film. A rapid decrease in water contact angle of the FD CNC film proves that the morphology of flakes and their orientation within the film has a strong influence in increasing water absorption capacity
Monovalent salt and pH-induced gelation of oxidized cellulose nanofibrils and starch networks: Combining rheology and small-angle X-Ray scattering
Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Addition of NaCl caused an increased stiffness of the OCNF:starch (1:1 wt%) blend gels, where salt played an important role in reducing the repulsive OCNF fibrillar interactions. The rheological properties of these hydrogels were unchanged at pH 5.0 to 9.0. However, at lower pH (4.0), the stiffness and viscosity of the OCNF and OCNF:starch gels appeared to increase due to proton-induced fibrillar interactions. In contrast, at higher pH (11.5), syneresis was observed due to the formation of denser and aggregated gel networks. Interactions as well as aggregation behaviour of these hydrogels were explored via ζ-potential measurements. Furthermore, the nanostructure of the OCNF gels was probed using small-angle X-ray scattering (SAXS), where the SAXS patterns showed an increase of slope in the low-q region with increasing salt concentration arising from aggregation due to the screening of the surface charge of the fibrils
The need for novel cryoprotectants and cryopreservation protocols: Insights into the importance of biophysical investigation and cell permeability
Background: Cryopreservation is a key method of preservation of biological material for both medical treatments and conservation of endangered species. In order to avoid cellular damage, cryopreservation relies on the addition of a suitable cryoprotective agent (CPA). However, the toxicity of CPAs is a serious concern and often requires rapid removal on thawing which is time consuming and expensive.Scope of review: The principles of Cryopreservation are reviewed and recent advances in cryopreservation methods and new CPAs are described. The importance of understanding key biophysical properties to assess the cryoprotective potential of new non-toxic compounds is discussed.Major conclusions: Knowing the biophysical properties of a particular cell type is crucial for developing new cryopreservation protocols. Similarly, understanding how potential CPAs interact with cells is key for optimising protocols. For example, cells with a large osmotically inactive volume may require slower addition of CPAs. Similarly, a cell with low permeability may require a longer incubation time with the CPA to allow adequate penetration. Measuring these properties allows efficient optimisation of cryopreservation protocols.General significance: Understanding the interplay between cells and biophysical properties is important not just for developing new, and better optimised, cryopreservation protocols, but also for broader research into topics such as dehydration and desiccation tolerance, chilling and heat stress, as well as membrane structure and function
Effect of Deep Eutectic Solvent Nanostructure on Phospholipid Bilayer Phases
Phospholipids are shown by solvent
penetration experiments to form
lamellar phases and spontaneously spawn vesicles in a wide range of
deep eutectic solvents (DESs) composed of alkylammonium halide salts
and glycerol or ethylene glycol, which are shown to be nanostructured
by X-ray scattering. In contrast with molecular solvents, the chain
melting temperature of each phospholipid, which determines the stability
of the swellable bilayer phase, depends on the structure of the cation,
anion, and molecular H-bond donor that constitute the DES. Chain melting
is most sensitive to the length of the alkyl chain of the cation,
which is partitioned between apolar domains in the bulk, nanostructured
DES and those within the lipid bilayer. This is moderated by the structures
of the anion and the molecular hydrogen bond donor, which determine
the extent of polar/apolar segregation in the bulk liquid
Structural and chemical heterogeneity in ancient glass probed using gas overcondensation, X-ray tomography, and solid-state NMR
Rare ancient glasses have complex, multi-scale structures requiring more sophisticated and non-destructive pore characterisation techniques than usual. Homotattic patch models for nitrogen adsorption gave better fits to the isotherm data, more accurate void space descriptors, and also greater understanding of the underlying physical factors affecting adsorption, than standard BET. These homotattic patch models revealed the critical role of iron impurities in determining adsorption behaviour. Non-destructive sodium-23 NMR relaxometry validated the homotattic patch model for some natron glasses, and, in turn, was validated using multiple quantum magic-angle spinning (MQMAS) 23Na NMR. X-ray tomography images of the glasses showed the presence of large macroporous bubbles, while FEG-SEM revealed nanopores within the glass matrix. A newly-developed, gas overcondensation technique, suitable for small amounts of low porosity material, assessed the inter-relationship between the disparate levels in this hierarchical porosity. This technique demonstrated that the nanoporosity did not form a âcoronaâ around the bubbles, due to leaching from the glass, as initially supposed from tomography data, but was completely disconnected, and, thus, is probably associated with glass alkalinity. Gas overcondensation is demonstrated as a non-destructive alternative to mercury porosimetry for probing multi-scale porosity in rare artefacts
Mapping the ThreeâDimensional Nanostructure of the Ionic LiquidâSolid Interface Using Atomic Force Microscopy and Molecular Dynamics Simulations
Abstract Ionic liquids (ILs) are a widely investigated class of solvents for scientific and industrial applications due to their desirable and âtunableâ properties. The ILâsolid interface is a complex entity, and despite intensive investigation, its true nature remains elusive. The understanding of the ILâsolid interface has evolved over the last decade from a simple 1D double layer, to a 2D ordered interface, and finally a liquidâspecific, complex 3D ordered liquid interface. However, most studies depend solely on one technique, which often only examine one aspect of the interfacial nanostructure. Here, a holistic study of the protic ILâsolid interface is presented, which provides a more detailed picture of IL interfacial solvation. The 3D nanostructure of the ethylammonium nitrate (EAN)âmica interface is investigated using a combination of 1D, 2D, and 3D amplitude modulatedâatomic force microscopy and molecular dynamics simulations. Importantly, it is found that the EANâmica interface is more complex than previously reported, possessing surfaceâadsorbed, nearâsurface, surfaceânormal, and lateral heterogeneity, which propagates at relatively large distances from the solid substrate. The work presented in this study meaningfully enhances the understanding of the ILâsolid interface
Behavior of Citrate-Capped Ultrasmall Gold Nanoparticles on a Supported Lipid Bilayer Interface at Atomic Resolution
Nanomaterials have the potential to transform biological and biomedical research, with applications ranging from drug delivery and diagnostics to targeted interference of specific biological processes. Most existing research is aimed at developing nanomaterials for specific tasks such as enhanced biocellular internalization. However, fundamental aspects of the interactions between nanomaterials and biological systems, in particular, membranes, remain poorly understood. In this study, we provide detailed insights into the molecular mechanisms governing the interaction and evolution of one of the most common synthetic nanomaterials in contact with model phospholipid membranes. Using a combination of atomic force microscopy (AFM) and molecular dynamics (MD) simulations, we elucidate the precise mechanisms by which citrate-capped 5 nm gold nanoparticles (AuNPs) interact with supported lipid bilayers (SLBs) of pure fluid (DOPC) and pure gel-phase (DPPC) phospholipids. On fluid-phase DOPC membranes, the AuNPs adsorb and are progressively internalized as the citrate capping of the NPs is displaced by the surrounding lipids. AuNPs also interact with gel-phase DPPC membranes where they partially embed into the outer leaflet, locally disturbing the lipid organization. In both systems, the AuNPs cause holistic perturbations throughout the bilayers. AFM shows that the lateral diffusion of the particles is several orders of magnitude smaller than that of the lipid molecules, which creates some temporary scarring of the membrane surface. Our results reveal how functionalized AuNPs interact with differing biological membranes with mechanisms that could also have implications for cooperative membrane effects with other molecules