Search Results (19)

This study employs advanced structural characterization techniques, including anomalous small-angle X-ray scattering (ASAXS), small-angle X-ray scattering (SAXS), and X-ray photoelectron spectroscopy (XPS), to investigate erbium (Er³⁺)-doped silica-based glass-ceramic thin films synthesized via the sol–gel method. This research examines the SiO₂-TiO₂ and SiO₂-TiO₂-PO_2.5 systems, focusing on the formation, dispersion, and structural integration of Er³⁺-containing nanocrystals within the amorphous matrix under different thermal treatments. Synchrotron radiation tuned to the L_III absorption edge of erbium enabled ASAXS measurements, providing element-specific details about the localization of Er³⁺ ions. The findings confirm their migration into crystalline phases, such as erbium phosphate (EPO) and erbium titanate (ETO). SAXS and Guinier analysis quantified nanocrystal sizes, revealing trends influenced by their composition and heat treatment. Complementary XPS analysis of the Er 5p core-level states provided detailed information on the chemical and electronic environment of the Er³⁺ ions, confirming their stabilization within the crystalline structure. Transmission electron microscopy (TEM) highlighted the nanoscale morphology, verifying the aggregation of Er³⁺ ions into well-defined nanocrystals. The results offer a deeper understanding of their size, distribution, and interaction with the surrounding matrix. Full article

The common Deep Eutectic Solvent (DES) ‘ethaline’ (1:2 choline chloride:ethylene glycol) was examined here as a basis for the self-assembly of the surfactant dodecyltrimethylammonium bromide (C₁₂TAB). A phase diagram was constructed, showing evidence for a L₁ (micellar) phase, confirmed by tensiometry to have a room temperature critical micelle concentration (CMC) of 1.2 wt.%. Small angle neutron scattering (SANS) measurements indicate formation of interacting globular micelles with slightly smaller apparent radii than in water. The apparent mesophase/multiphase region was studied using SWAXS, demonstrating rich mesoscopic lyotropic liquid crystalline phase behaviour, with evidence for lamellar L_α peaks, alongside potential co-crystalline phases. We attempted to tailor the self-assembly by studying binary DES containing longer diols including 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol, and ternary DES where the HBD component was a 1:1 ethylene glycol:diol mixture. However, synchrotron SAXS showed that only ternary ‘propethaline’ mixtures displayed signs of self-assembly and micellization, perhaps due to the reduction in calculated Gordon parameter, which decreases linearly with increasing alkyl chain length. Systematic differences were thus observed in the ability of the solvents to modulate assembly, from globular micelles in ChCl:EG, to weaker assembly in long-tail DES, and complete solubilisation in butaline and pentaline. Full article

Freezing has been widely used for long-term food preservation. However, freezing-thawing (FT) treatment usually influences the texture and structure of food gels such as konjac. For their texture control after FT treatment, it is important to clarify the structural change of food gels during the FT process. In this study, we investigated the aggregated structures of konjac glucomannan (GM) gels during the FT process using simultaneous synchrotron small-angle X-ray/wide-angle X-ray scattering (SAXS/WAXS) techniques. The FT treatment resulted in more crystallization of GM, and consequently, a large increase in compressive stress. In-situ SAXS/WAXS measurements revealed the following findings: on freezing, water molecules came out of the aggregated phase of GM and after the thawing, they came back into the aggregated phase, but the aggregated structure did not return to the one before the freezing; the gel network enhanced the inhomogeneity due to the growth of ice crystals during freezing. Furthermore, we examined the influence of additives such as polyvinyl (alcohol) (PVA) and antifreeze glycoprotein (AFGP) on the mechanical and structural properties of freeze-thawed GM gels. Although the addition of PVA and AFGP suppressed the crystallization of GM, it could not prevent the growth of ice crystals and the increase in the inhomogeneity of the gel network. As a result, the compressive stresses for freeze-thawed GM gels containing PVA or AFGP were significantly higher compared with those of GM gels without FT treatments, although they were lower than those of freeze-thawed GM gels. The findings of this study may be useful for not only the texture control of freeze-thawed foods but also the improvement of the mechanical performance of the biomaterials. Full article

Fibrotic scarring is prevalent in a range of collagenous tissue disorders. Understanding the role of matrix biophysics in contributing to fibrotic progression is important to develop therapies, as well as to elucidate biological mechanisms. Here, we demonstrate how microfocus small-angle X-ray scattering (SAXS), with in situ mechanics and correlative imaging, can provide quantitative and position-resolved information on the fibrotic matrix nanostructure and its mechanical properties. We use as an example the case of keloid scarring in skin. SAXS mapping reveals heterogeneous gradients in collagen fibrillar concentration, fibril pre-strain (variations in D-period) and a new interfibrillar component likely linked to proteoglycans, indicating evidence of a complex 3D structure at the nanoscale. Furthermore, we demonstrate a proof-of-principle for a diffraction-contrast correlative imaging technique, incorporating, for the first time, DIC and SAXS, and providing an initial estimate for measuring spatially resolved fibrillar-level strain and reorientation in such heterogeneous tissues. By application of the method, we quantify (at the microscale) fibrillar reorientations, increases in fibrillar D-period variance, and increases in mean D-period under macroscopic tissue strains of ~20%. Our results open the opportunity of using synchrotron X-ray nanomechanical imaging as a quantitative tool to probe structure–function relations in keloid and other fibrotic disorders in situ. Full article

In this study, nanocomposites based on polycaprolactone (PCL) and two types of mesoporous silicas, MCM-41 and SBA-15, were attained by melt extrusion. The effect of the silica incorporated within the PCL matrix was observed, firstly, in the morphological characteristics and degradation behavior of the resultant composites. DSC experiments provided information on the existence of confinement in the PCL–SBA-15 materials through the appearance of an additional small endotherm, located at about 25–50 °C, and attributed to the melting of constrained crystallites. Displacement to a slightly lower temperature of this endothermic event was observed in the first heating run of PCL–MCM-41 composites, attributed to the inferior pore size in the MCM-41 particles. Thus, this indicates variations in the inclusion of PCL chains within these two mesostructures with different pore sizes. Real-time variable-temperature small-angle X-ray scattering (SAXS) experiments with synchrotron radiation were crucial to confirm the presence of PCL within MCM-41 and SBA-15 pores. Accurate information was also deduced from these measurements regarding the influence of these two mesoporous MCM-41 and SBA-15 silicas on PCL long spacing. The differences found in these morphological and structural features were responsible for the ultimate mechanical response exhibited by the two sets of PCL nanocomposites, with a considerably higher increase of mechanical parameters in the SBA-15 family. Full article

In this study, the nanoscale transformation of the polylactic-co-glycolic acid (PLGA) internal structure, before and after its supercritical carbon dioxide (sc-CO₂) swelling and plasticization, followed by foaming after a CO₂ pressure drop, was studied by small-angle X-ray scattering (SAXS) for the first time. A comparative analysis of the internal structure data and porosity measurements for PLGA scaffolds, produced by sc-CO₂ processing, on a scale ranging from 0.02 to 1000 μm, was performed by SAXS, helium pycnometry (HP), mercury intrusion porosimetry (MIP) and both “lab-source” and synchrotron X-ray microtomography (micro-CT). This approach opens up possibilities for the wide-scale evaluation, computer modeling, and prediction of the physical and mechanical properties of PLGA scaffolds, as well as their biodegradation behavior in the body. Hence, this study targets optimizing the process parameters of PLGA scaffold fabrication for specific biomedical applications. Full article

We describe the updated size-exclusion chromatography small angle X-ray scattering (SEC-SAXS) set-up used at the P12 bioSAXS beam line of the European Molecular Biology Laboratory (EMBL) at the PETRAIII synchrotron, DESY Hamburg (Germany). The addition of size exclusion chromatography (SEC) directly on-line to the SAXS capillary has become a well-established approach to reduce the effects of the sample heterogeneity on the SAXS measurements. The additional use of multi-angle laser light scattering (MALLS), UV absorption spectroscopy, refractive index (RI), and quasi-elastic light scattering (QELS) in parallel to the SAXS measurements enables independent molecular weight validation and hydrodynamic radius estimates. This allows one to address sample monodispersity as well as conformational heterogeneity. The benefits of the current SEC-SAXS set-up are demonstrated on a set of selected standard proteins. The processed SEC-SAXS data and models are provided in the Small Angle Scattering Biological Data Bank (SASBDB) and are labeled as “bench-marked” datasets that include the unsubtracted data frames spanning the respective SEC elution profiles and corresponding MALLS-UV-RI-QELS data. These entries provide method developers with datasets suitable for testing purposes, in addition to an educational resource for SAS data analysis and modeling. Full article

This study reports a new strategy for enzyme immobilization based on passive immobilization in neat and magnetically responsive polyamide 4 (PA4) highly porous particles. The microsized particulate supports were synthesized by low-temperature activated anionic ring-opening polymerization. The enzyme of choice was laccase from Trametes versicolor and was immobilized by either adsorption on prefabricated PA4 microparticles (PA4@iL) or by physical in situ entrapment during the PA4 synthesis (PA4@eL). The surface topography of all PA4 particulate supports and laccase conjugates, as well as their chemical and physical structure, were studied by microscopic, spectral, thermal, and synchrotron WAXS/SAXS methods. The laccase content and activity in each conjugate were determined by complementary spectral and enzyme activity measurements. PA4@eL samples displayed >93% enzyme retention after five incubation cycles in an aqueous medium, and the PA4@iL series retained ca. 60% of the laccase. The newly synthesized PA4-laccase complexes were successfully used in dyestuff decolorization aiming at potential applications in effluent remediation. All of them displayed excellent decolorization of positively charged dyestuffs reaching ~100% in 15 min. With negative dyes after 24 h the decolorization reached 55% for PA4@iL and 85% for PA4@eL. A second consecutive decolorization test revealed only a 5–10% decrease in effectiveness indicating the reusability potential of the laccase-PA4 conjugates. Full article

Nanocomposites based on isotactic polypropylene (iPP) and mesoporous silica particles of either MCM-41 or SBA-15 were prepared by melt extrusion. The effect of the silica incorporated into an iPP matrix was firstly detected in the degradation behavior and in the rheological response of the resultant composites. Both were ascribed, in principle, to variations in the inclusion of iPP chains within these two mesostructures, with well different pore size. DSC experiments did not provide information on the existence of confinement in the iPP-MCM-41 materials, whereas a small endotherm, located at about 100 °C and attributed to the melting of confined crystallites, is clearly observed in the iPP-SBA-15 composites. Real-time variable-temperature Small Angle X-ray Scattering (SAXS) experiments with synchrotron radiation turned out to be crucial to finding the presence of iPP within MCM-41 pores. From these measurements, precise information was also deduced on the influence of the MCM-41 on iPP long spacing since overlapping does not occur between most probable iPP long spacing peak with the characteristic diffractions from the MCM-41 hexagonal nanostructure in comparison with existing superposition in SBA-15-based materials. Full article

In this work, we investigated the local colloidal structure of ferrofluid, in the presence of the external magnetic field. The nanoparticles studied here are of the core-shell type, with the core formed by manganese ferrite and maghemite shell, and were synthesized by the coprecipitation method in alkaline medium. Measures of Small Angle X-ray Scattering (SAXS) performed in the Brazilian Synchrotron Light Laboratory (LNLS) were used for the study of the local colloidal structure of ferrofluid, so it was possible to study two levels of structure, cluster and isolated particles, in the regimes with and without applied magnetic field. In the methodology used here there is a combination of the information obtained in the system with and without magnetic field application. In this way, it is possible to undertake a better investigation of the colloidal dispersion. The theoretical formalism used: (i) the unification equation proposed by Beaucage G.; (ii) the analysis of the radial distribution function $p(r)$ and (iii) theoretical calculation of the radius of gyration as a function of the moment of inertia of the spherical of n-nanoparticles. Full article

The effect of the graphene nanoplateletets (GNP), at concentration of 1, 5 and 10 wt %, in Poly ether ether ketone (PEEK) composite crystallization from melt and during cold crystallization were investigated by differential scanning calorimetry (DSC) and real time X-ray diffraction experiments. DSC results revealed a double effect of GNP: (a) nucleating effect crystallization from melt started at higher temperatures and (b) longer global crystallization time due to the restriction in the polymer chain mobility. This hindered mobility were proved by rheological behavior of nanocomposites, because to the increase of complex viscosity, G′, G″ with the GNP content, as well as the non-Newtonian behavior found in composites with high GNP content. Finally, real time wide and small angle synchrotron X-ray radiation (WAXS/SAXS) X-ray measurements showed that GNP has not affected the orthorhombic phase of PEEK nor the evolution of the crystal phase during the crystallization processes. However, the correlation length of the crystal obtained by WAXS and the long period (L) by SAXS varied depending on the GNP content. Full article

Radiography has long been the standard approach to characterize carious lesions. Spatially resolved X-ray diffraction, specifically small-angle X-ray scattering (SAXS), has recently been applied to caries research. The aims of this combined SAXS and micro computed tomography (µCT) study were to locally characterize and compare the micro- and nanostructures of one natural carious lesion and of one artificially induced enamel lesion; and demonstrate the feasibility of an automated approach to combined SAXS and µCT data in segmenting affected and unaffected enamel. Enamel, demineralized by natural or artificial caries, exhibits a significantly reduced X-ray attenuation compared to sound enamel and gives rise to a drastically increased small-angle scattering signal associated with the presence of nanometer-size pores. In addition, X-ray scattering allows the assessment of the overall orientation and the degree of anisotropy of the nanostructures present. Subsequent to the characterization with µCT, specimens were analyzed using synchrotron radiation-based SAXS in transmission raster mode. The bivariate histogram plot of the projected data combined the local scattering signal intensity with the related X-ray attenuation from µCT measurements. These histograms permitted the segmentation of anatomical features, including the lesions, with micrometer precision. The natural and artificial lesions showed comparable features, but they also exhibited size and shape differences. The clear identification of the affected regions and the characterization of their nanostructure allow the artificially induced lesions to be verified against selected natural carious lesions, offering the potential to optimize artificial demineralization protocols. Analysis of joint SAXS and µCT histograms objectively segmented sound and affected enamel. Full article

The relevance of coupling droplet-based Photonic Lab-on-a-Chip (PhLoC) platforms and Small-Angle X-Ray Scattering (SAXS) technique is here highlighted for the performance of high throughput investigations, related to the study of protein macromolecular interactions. With this configuration, minute amounts of sample are required to obtain reliable statistical data. The PhLoC platforms presented in this work are designed to allow and control an effective mixing of precise amounts of proteins, crystallization reagents and buffer in nanoliter volumes, and the subsequent generation of nanodroplets by means of a two-phase flow. Spectrophotometric sensing permits a fine control on droplet generation frequency and stability as well as on concentration conditions, and finally the droplet flow is synchronized to perform synchrotron radiation SAXS measurements in individual droplets (each one acting as an isolated microreactor) to probe protein interactions. With this configuration, droplet physic-chemical conditions can be reproducibly and finely tuned, and monitored without cross-contamination, allowing for the screening of a substantial number of saturation conditions with a small amount of biological material. The setup was tested and validated using lysozyme as a model of study. By means of SAXS experiments, the proteins gyration radius and structure envelope were calculated as a function of protein concentration. The obtained values were found to be in good agreement with previously reported data, but with a dramatic reduction of sample volume requirements compared to studies reported in the literature. Full article

We investigated the mechanical, swelling, and structural properties of mechanically tough clay/sodium polyacrylate (PAAS) hydrogels prepared by simple mixing. The gels had large swelling ratios, reflecting the characteristics of the constituent polymer. The swelling ratios initially increased with the increase of the swelling time, and then attained maximum values. Afterwards, they decreased with an increase of the swelling time and finally became constant. An increase in the clay concentration lead to a decrease in the swelling ratios, whereas an increase in the PAAS concentration lead to an increase in the swelling ratios. Tensile measurements indicated that the toughness for clay/PAAS (M_w = 3.50 × 10⁶) gels was several hundred times larger than that of clay/PAAS (M_w = 5.07 × 10⁵) gels, i.e., the use of ultra-high molecular weight PAAS is essential for fabricating mechanically tough clay/PAAS blend hydrogels. Synchrotron small-angle X-ray scattering (SAXS) results showed that the SAXS intensity measured at small scattering angles decreased with an increase in the clay concentration, indicating that the interparticle interactions were more repulsive at higher concentrations. The decrease of the scattering intensity at high clay concentrations was larger for the clay/PAAS (M_w = 5.07 × 10⁵) gel system than for the clay/PAAS (M_w = 3.50 × 10⁶) gel system. Full article

An effective antitumor remedy is yet to be developed. All previous approaches for a targeted delivery of anticancer medicine have relied on trial and error. The goal of this study was to use structural insights gained from the study of delivery systems and malignant cells to provide for a systematic approach to the development of next-generation drugs. We used doxorubicin (Dox) liposomal formulations. We assayed for cytotoxicity via the electrical current exclusion method. Dialysis of the samples yielded information about their drug release profiles. Information about the surface of the delivery systems was obtained through synchrotron small-angle X-ray scattering (SAXS) measurements. SAXS measurements revealed that Dox-loading yielded an abraded surface of our Dox liposomal formulation containing soybean oil, which also correlated with an effective reduction of the survival of carcinoma cells. Furthermore, a dialysis assay revealed that a higher burst of Dox was released from soybean oil-containing preparations within the first five hours. We conclude from our results that an abraded surface of Dox-loaded drug delivery system increases their efficacy. The apparent match between surface geometry of drug delivery systems and target cells is suggested as a steppingstone for refined development of drug delivery systems. This is the first study to provide a systematic approach to developing next-generation drug carrier systems using structural insights to guide the development of next-generation drug delivery systems with increased efficacy and reduced side effects. Full article