Synchrotron Small Angle Research Articles

Ionizable Lipid Containing Nanocarriers for Antimicrobial Agent Delivery

Antimicrobial resistance (AMR) poses a global health crisis demanding innovative solutions. Traditional antibiotics, though pivotal over the past century in combating bacterial infections, face diminished efficacy against evolving bacterial defense mechanisms, especially in Gram‐negative strains. This study explores self‐assembled ionizable lipid nanoparticles (LNPs) with the incorporation of two ionizable lipid components (one cationic, one anionic) in nanocarriers for advanced antimicrobial drug delivery of the broad‐spectrum antibiotic Piperacillin (Pip). Incorporating cationic ionizable lipid ALC‐0315, recognized as a functional lipid in the Pfizer‐BioNTech mRNA‐based SARS‐CoV‐2 vaccine, into LNPs allowed mesophase transition, pH responsiveness, and ionization behavior in acidic environments found in sites of bacterial infections, to be studied using synchrotron small angle X‐ray scattering, dynamic light scattering, and a 2‐(p‐toluidino)‐6‐naphthalene sulfonic acid assay. Incorporating another anionic ionizable lipid, oleic acid not only modulates the LNPs’ physicochemical properties, such as size, internal phase nanostructure, and surface charge but also synergistically enhances the antimicrobial potency together with ALC‐0315 with a benefit enhancing permeability and fusion with bacterial membranes. This study introduces a strategy for tailoring ionizable lipid compositions in LNPs, providing a new approach to antimicrobial treatment contributing to the fight against AMR.

Lyotropic Liquid Crystalline Phase Nanostructure and Cholesterol Enhance Lipid Nanoparticle Mediated mRNA Transfection in Macrophages

AbstractMacrophages are unique immune cells attracting growing attention as a potential candidate for cell‐based therapy for infectious diseases and cancer. Strategies that can reprogramme or gene‐edit macrophages hold potential across a spectrum of acute and chronic conditions. Herein, lipid nanoparticles (LNPs) are developed containing the ionizable lipid SM‐102, helper lipid monoolein which is known for self‐assembly in aqueous solutions into the inverse cubic lyotropic liquid crystalline mesophase, and cholesterol as an mRNA nanocarrier. The immortalized alveolar macrophage cell line (MH‐S cells) is utilized to investigate how cholesterol concentration impacts on mRNA delivery which is further validated using primary mouse alveolar macrophages isolated from the bronchoalveolar compartment and human monocyte derived macrophages. By using high‐throughput synchrotron small angle X‐ray scattering (SAXS), an acidification‐induced non‐ordered to ordered internal nanostructure transition of the formulated LNPs is observed, following the transition sequence of inverse micellar to hexagonal to cubic mesophase in the pH range from 7 to 4. Cholesterol is identified as another crucial component for superior mRNA transfection in macrophages, contributing to nanostructure transition and protein corona variation. Successful ex vivo mRNA transfection is also achieved in primary macrophages, highlighting the prospectivity of reprogramming macrophages as a cell therapy for lung diseases.

Research on Improving the Pre‐Oxidation Process of the Excellent Mechanical Strength Carbon Fiber

AbstractThis study uses synchrotron wide‐angle X‐ray diffraction (WAXD) and synchrotron small angle X‐ray scattering (SAXS) to carry out an in situ study of the pre‐oxidation process of polyacrylonitrile (PAN) fibers with two different preparation processes. Through analysis of 2D WAXD/SAXS data, this study divides the evolution of PAN fiber's crystal and microporous structures during pre‐oxidation into three and two stages, respectively. The evolution of PAN fiber's crystal structure during pre‐oxidation can be divided into three stages: 1) Initial stage: small‐sized crystals melt, crystal orientation decreases, and no cyclization reactions occur. 2) Intermediate stage: cyclization reactions happen in the amorphous region, leading to increased crystal size, crystal orientation, and crystallinity. 3) Final stage: cyclization reactions occur in the crystal region, resulting in reduced crystal size and orientation. The evolution of microporous structure can be divided into two stages: microporous shrinkage stage and microporous expansion stage. These features are analyzed using 2D WAXD/SAXS techniques. This study provides valuable references and guidance for the industrial production of PAN fibers by exploring the mechanism of the pre‐oxidation process in‐depth.

Study of the fibrinogen structure by the method of small-angle synchrotron scattering

Fibrinogen is synthesized by human liver cells and is constantly present in the blood. Protein is the main factor of blood clotting and largely determines the blood viscosity. Any damage to a blood vessel or tissue in the body triggers hemostasis (blood clotting). Fibrinogen under the action of thrombin is converted into fibrin, an insoluble biopolymer, which is the basis of a blood clot that provides hemostasis. Apart of wound healing, fibrinogen is involved in the pathogenesis of malignant neoplasms. Fibrinogen labeled with 125I is used to diagnose thrombosis because it penetrates blood clots. We present the results of studying the structure of fibrinogen in human blood plasma using small-angle X-ray scattering (SAX). The SAX method, widely used in analysis of supra-atomic structures of substances, provides determination of the size of domains present in proteins, their shape, as well as the conformation of segments of chain macromolecules in the form of Gaussian and persistent chains. An important feature of the method is the possibility of studying biological objects in their natural state, without any special pretreatment. It is shown that globular domains of two sizes (diameters — 8.4 and 4 nm, respectively) are present in the structure of fibrinogen. The domains are coupled by polypeptide chains (α, β, γ) twisted in the form of spiral coils. The stiffness of the chains estimated as a persistent length was 3.1. The results obtained can be used in surgical practice and replacement therapy when creating fibrin glue as a hemostatic drug that stops bleeding with minimal invasiveness of intervention, and drugs that eliminate fibrinogen deficiency in the blood.

Human Antimicrobial Peptide Triggered Colloidal Transformations in Bacteria Membrane Lipopolysaccharides.

Growing concerns of bacterial resistance against conventional antibiotics shifts the research focus toward antimicrobial peptide (AMP)-based materials. Most AMPs kill gram-negative bacteria by destroying their inner membrane, but have to first pass the outer membrane covered with lipopolysaccharides (LPS). Their interplay with the LPS is crucial for bactericidal activity, but is yet to be elucidated in detail. In this study, self-assemblies of Escherichia coli LPS with the human cathelicidin AMP LL-37, free and encapsulated into glyceryl monooleate (GMO) lipid nanoparticles, are analyzed using synchrotron small angle X-ray scattering, dynamic light scattering, and cryogenic transmission electron microscopy. Circular dichroism spectroscopy is used to study modifications in LL-37's secondary structure. LPS is found to form elongated micelles and the addition of LL-37 induces their transformation to multilamellar structures. LPS' addition to GMO cubosomes triggers the swelling of the internal cubic structure, while in multilamellar GMO/LL-37 nanocarriers it causes transitions into unstructured particles. The insights on the interactions among LPS and LL-37, in its free form or encapsulated in GMO dispersions, may guide the design of LPS-responsive antimicrobial nanocarriers. The findings may further assist the formulation of antimicrobial nanomaterials with enhanced penetration of LPS layers for improved destruction of bacterial membranes.

In Situ Scattering Studies of Crystallization Kinetics in a Phase-Separated Zr–Cu–Fe–Al Bulk Metallic Glass

Thermal stability and the crystallization kinetics of a phase-separated Zr–Cu–Fe–Al bulk metallic glass were investigated using in situ high-energy synchrotron X-ray and neutron diffraction, as well as small-angle synchrotron X-ray scattering. It was revealed that this glass with excellent glass-forming ability possesses a two-step crystallization behavior. The crystalline products and their evolution sequence are more complicated than a homogeneous Zr–Cu–Al glass with average glass-forming ability. The experimental results indicate that a finely distributed nanometer-sized cubic Zr2Cu phase forms first and then transforms to a tetragonal Zr2Cu phase, while the matrix transforms to an orthorhombic Zr3Fe phase. The strength of the Zr–Cu–Fe–Al composite containing cubic Zr2Cu phase and glass matrix increases, and the plasticity also improves compared to the as-cast Zr–Cu–Fe–Al bulk metallic glass. Our results suggest that the formation of multiple and complex crystalline products would be the characteristics of the Zr–Cu–Fe–Al glass with better glass-forming ability. Our study may shed light on the synthesis of bulk-sized glass–nanocrystals composites of high strength and good plasticity.

Shear-Induced Ordering of Nanopores and Instabilities in Concentrated Surfactant Mesh Phases.

Mixed surfactant systems with strongly bound counterions show many interesting phases such as the random mesh phase consisting of a disordered array of defects (water-filled nanopores in the bilayers). The present study addresses the non-equilibrium phase transition of the random mesh phase under shear to an ordered mesh phase with a high degree of coherence between nanopores in three dimensions. In situ small-angle synchrotron X-ray study under different shear stress conditions shows sharp Bragg peaks in the X-ray diffraction, successfully indexed to the rhombohedral lattice with R3̅m space group symmetry. The ordered mesh phase shows isomorphic twinning and buckling at higher shear stress. Our experimental studies bring out rich non-equilibrium phase transitions in concentrated cationic surfactant systems with strongly bound counterions hitherto not well explored and provide motivation for a quantitative understanding.

Pressure Induced Assembly and Coalescence of Lead Chalcogenide Nanocrystals.

We report here pressure induced nanocrystal coalescence of ordered lead chalcogenide nanocrystal arrays into one-dimensional (1D) and 2D nanostructures. In particular, atomic crystal phase transitions and mesoscale coalescence of PbS and PbSe nanocrystals have been observed and monitored in situ respectively by wide- and small-angle synchrotron X-ray scattering techniques. At the atomic scale, both nanocrystals underwent reversible structural transformations from cubic to orthorhombic at significantly higher pressures than those for the corresponding bulk materials. At the mesoscale, PbS nanocrystal arrays displayed a superlattice transformation from face-centered cubic to lamellar structures, while no clear mesoscale lattice transformation was observed for PbSe nanocrystal arrays. Intriguingly, transmission electron microscopy showed that the applied pressure forced both spherical nanocrystals to coalesce into single crystalline 2D nanosheets and 1D nanorods. Our results confirm that pressure can be used as a straightforward approach to manipulate the interparticle spacing and engineer nanostructures with specific morphologies and, therefore, provide insights into the design and functioning of new semiconductor nanocrystal structures under high-pressure conditions.

Inference of molecular structure for characterization and improvement of clinical grade immunocytokines

The use of immunomodulatory agents for the treatment of cancer is gaining a growing biopharmaceutical interest. Antibody-cytokine fusion proteins, namely immunocytokines, represent a promising solution for the regulation of the immune system at the site of disease. The three-dimensional arrangement of these molecules can profoundly influence their biological activity and pharmacokinetic properties. Structural techniques might provide important insight in the 3D arrangement of immunocytokines. Here, we performed structure investigations on clinical grade fusion proteins L19-IL2, IL12-L19L19 and L19L19-IL2 to elucidate their quaternary organization. Crystallographic characterization of the common L19 antibody fragment at a resolution of 2.0-Å was combined with low-resolution studies of the full-length chimeric molecules using small-angle synchrotron X-ray scattering (SAXS) and negative stain electron microscopy. Characterization of the full-length quaternary structures of the immunocytokines in solution by SAXS consistently supported the diabody structure in the L19-IL2 immunocytokine and allowed generation of low-resolution models of the chimeric proteins L19L19-IL2 and IL12-L19L19. Comparison with 3D reconstructions obtained from negative-stain electron microscopy revealed marked flexibility associated to the linker regions connecting the cytokine and the antibody components of the chimeric proteins. Collectively, our results indicate that low-resolution molecular structure characterizations provide useful complementary insights for the quality control of immunocytokines, constituting a powerful tool to guide the design and the subsequent optimization steps towards clinical enhancement of these chimeric protein reagents.

Morphological Characteristics of Amylose‐Poly(tetrahydrofuran) Inclusion Complexes Depending on Temperature and Concentration

AbstractIn this study, inclusion complexes of amylose using poly(tetrahydrofuran) (PTHF) as a guest molecule are studied. The effect of PTHF inclusion into the hydrophobic cavity of amylose is studied with different concentrations of PTHF. Attenuated total reflection fourier transform infrared spectroscopy and differential scanning calorimetry are used to confirm the formation of inclusion complexes and the structural properties of inclusion complexes are analyzed with synchrotron small angle X‐ray scattering (SAXS) and wide angle X‐ray scattering. SAXS patterns show that the complex does not display any self‐assembled lamellar structures due to the lower mobility of PTHF chains as compared to fatty acids. Different crystalline structures of inclusion complexes and arrangements of the PTHF molecules inside the amylose cavity are obtained at different temperatures. The results can play an effective role to understand the structural information of host–guest complexes with different physical and chemical properties of the guest compounds.

Inside polyMOFs: layered structures in polymer-based metal-organic frameworks.

In this report, we explore the internal structural features of polyMOFs consisting of equal mass ratios of metal-coordinating poly(benzenedicarboxylic acid) blocks and non-coordinating poly(ethylene glycol) (PEG) blocks. The studies reveal alternating lamellae of metal-rich, crystalline regions and metal-deficient non-crystalline polymer, which span the length of hundreds of nanometers. Polymers consisting of random PEG blocks, PEG end-blocks, or non-coordinating poly(cyclooctadiene) (COD) show similar alternation of metal-rich and metal-deficient regions, indicating a universal self-assembly mechanism. A variety of techniques were employed to interrogate the internal structure of the polyMOFs, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and small-angle synchrotron X-ray scattering (SAXS). Independent of the copolymer architecture or composition, the internal structure of the polyMOF crystals showed similar lamellar self-assembly at single-nanometer length scales.

Study of Kinetics of Solid Phase Transition in Tetracosane С24Н50 by High-Resolution Synchrotron X-Ray Powder Diffraction

Using the small-angle synchrotron X-ray diffraction method at the research facility “BELOK” of the Kurchatov synchrotron radiation source at the NRC Kurchatov Institute, it was shown that the first-order solid phase transition in tetracosane C24H50 passes according to a heterogeneous mechanism in a narrow temperature range ΔT ~ 1 K in accordance with the theory of diffuse phase transitions.

Re-entrant direct hexagonal phases in a lyotropic system of surfactant induced by an ionic liquid

ABSTRACTIn the present study, an ionic liquid (IL), known as green solvent, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) with four carbons in the hydrophobic chain (C-4) has been used as an additive to modify the self-assembled aggregates of an anionic surfactant sodium dodecyl sulfate (SDS) and then the evolution of the liquid crystalline phases has been investigated. Small angle synchrotron x-ray diffraction study has revealed an unprecedented phase sequence where a hexagonal phase (HI) of direct cylindrical micelles is observed to evolve to another hexagonal phase (HII) of, again, direct cylindrical micelles with a lamellar phase () as the intermediate. The rheological data and the theoretical calculations have confirmed the phases. To understand such a phase behaviour of the system, the work is extended by considering the ionic liquids with the same head group but of shorter (C-2) and longer (C-10) hydrocarbon chains compared to BMIM-BF4. While the shorter chain IL causes the hexagonal phase to form rectangular (R) phase, the longer chain is observed to induce the lamellar phase (). The molecular mechanism of appearance of such different phases has been discussed.

Non-Isothermal Crystallization Behavior of PEEK/Graphene Nanoplatelets Composites from Melt and Glass States.

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.

Effect of molecular structures on static and dynamic compression properties of clay and amphiphilic clay/carbon nanofibers used as fillers in UHMWPE/composites for high‐energy‐impact loading

ABSTRACTThree different ultrahigh‐molecular‐weight polyethylene (UHMWPE)–clay nanocomposites (Muscovite, Cloisite 30B and amphiphilic clay/carbon nanofibers) were investigated with the nanocomposite nanomorphology studied before and after dynamic mechanical compressive tests at high strain rates. Their material structure and thermal properties were investigated using techniques such as step‐scan differential scanning calorimetry, split Hopkinson pressure bar, synchrotron small angle X‐ray scattering (SAXS), and dynamic mechanical analysis. Results were associated with morphological changes observed after deformation. chemical vapor deposition (CVD)‐modified nanocomposite, due to the molecular bonding and the extra functional groups, is designed with crystalline structures with fewer defects and higher stability. The increase in particulate/polymer interactions observed for the CVD‐modified material decreased the elongation in the quasi‐static test. However, the dynamic mechanical behavior contradicted the quasi‐static behavior because at very high strain rates there was not sufficient time for the interlamellar and intralamellar defect facilitated plastic flow and the material transitioned through the glassy state. The SAXS results show that deformation strongly induced changes in the UHMWPE and UHMWPE–clay nanocomposite morphology. SAXS indicates that CVD‐modified samples became more compact and dense, thus corroborating the formation of additional secondary bonds between structures and/or the carbon nanofibers alignment. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47094.

How ionic species structure influences phase structure and transitions from protic ionic liquids to liquid crystals to crystals.

The phase behaviour of n-alkylammonium (C6 to C16) nitrates and formates has been characterised using synchrotron small angle and wide angle X-ray scattering (SAXS/WAXS), differential scanning calorimetry (DSC), cross polarised optical microscopy (CPOM) and Fourier transform infrared spectroscopy (FTIR). The protic salts may exist as crystalline, liquid crystalline or ionic liquid materials depending on the alkyl chain length and temperature. n-Alkylammonium nitrates with n ≥ 6 form thermotropic liquid crystalline (LC) lamellar phases, whereas n ≥ 8 was required for the formate series to form this LC phase. The protic ionic liquid phase showed an intermediate length scale nanostructure resulting from the segregation of the polar and nonpolar components of the ionic liquid. This segregation was enhanced for longer n-alkyl chains, with a corresponding increase in the correlation length scale. The crystalline and liquid crystalline phases were both lamellar. Phase transition temperatures, lamellar d-spacings, and liquid correlation lengths for the n-alkylammonium nitrates and formates were compared with those for n-alkylammonium chlorides and n-alkylamines. Plateau regions in the liquid crystalline to liquid phase transition temperatures as a function of n for the n-alkylammonium nitrates and formates are consistent with hydrogen-bonding and cation-anion interactions between the ionic species dominating alkyl chain-chain van der Waals interactions, with the exception of the mid chained hexyl- and heptylammonium formates. The d-spacings of the lamellar phases for both the n-alkylammonium nitrates and formates were consistent with an increase in chain-chain layer interdigitation within the bilayer-based lamellae with increasing alkyl chain length, and they were comparable to the n-alkylammonium chlorides.

Evaluation of Structural in Homogeneity by Small Angle Synchrotron Radiation X-ray Scattering and Elucidation of Plastic Deformation Induced Nanocrystallization Behavior in Zr-Cu-Ni-Al-(Pd, Pt, Ag or Au) Bulk Metallic Glasses

Evaluation of Structural in Homogeneity by Small Angle Synchrotron Radiation X-ray Scattering and Elucidation of Plastic Deformation Induced Nanocrystallization Behavior in Zr-Cu-Ni-Al-(Pd, Pt, Ag or Au) Bulk Metallic Glasses

Characterization and stability study of cranberry flavonoids in lipid liquid crystalline systems

The main objective of the present study was to investigate mixtures of soy phosphatidylcholine (SPC) and glycerol dioleate (GDO) as encapsulation matrices for cranberry flavonoids. The effects of flavonoids loading into non‐aqueous formulations, non‐lamellar liquid crystalline phases, and their colloidal dispersions were studied by using synchrotron small angle X‐ray diffraction, dynamic light scattering. Flavonoids incorporation is discussed with respect to the lipid aggregation behavior, self‐assembled nanostructure, and chemical stability by using antioxidant activity assay. The obtained results show that SPC/GDO‐based formulations can incorporate relatively high amounts of flavonoids and serve as liquid crystalline delivery vehicles in the form of bulk phases or colloidal dispersions.Practical applications: Our results show that SPC/GDO‐based formulations can incorporate relatively high amounts of cranberry flavonoids. The effect flavonoid extracts on the nanostructure of bulk SPC/GDO LC phases are lipid weight ratio‐dependent. Flavonoids loaded into SPC/GDO‐based formulations and LC phases retain their antioxidant properties. The self‐assembled lipid liquid crystalline systems protect bioactive compounds from degradation. These facts are important for the community working in the field of self‐assembly of lipid structures, food chemistry, and delivery vehicles of nutraceuticals.Soy phosphatidylcholine lipids (SPC) and glycerol dioleate (GDO) formed lipid‐based liquid crystal systems can be successfully applied for entrapment of natural cranberries flavonoids. After full hydration LC formulations can easily create self‐assembled non‐lamellar LC systems with different nanostructures. The stability studies have shown that the flavonoids loaded in SPC/GDO‐based systems retain their antioxidant properties at least up to 30 days.

Structural properties of paeonol encapsulated liposomes at physiological temperature: Synchrotron small-angle and wide-angle X-ray diffraction studies

Structural properties of paeonol encapsulated liposomes at physiological temperature: Synchrotron small-angle and wide-angle X-ray diffraction studies

A new model for mesomorphic-monoclinic phase transition of isotactic polypropylene

In this study, Fourier transform infrared spectroscopy, synchrotron small-angle and wide-angle X-ray scattering were employed to reveal the underlying mechanism leading to conformational reorganization during mesomorphic-monoclinic phase transition. Results indicated that conformation reorganization occurred from 50 to 130 °C, evidenced by conformational infrared bands at 800 and 841 cm−1. The conformation reorganization led to an immediate increase in the density fluctuation but not induced phase transition immediately. Only when the long period started to increase quickly from 80 °C, can phase transition occur. This indicated that intrachain conformational ordering occurred prior to crystalline ordering. Moreover, temperature dependence of long period changed before and after phase transition, implying that chain sliding was the main driven force for the phase transition rather than rewinding and translation of single stems. With the new information obtained, a two-step model for phase transition was proposed. Within a single-chain bundle, two adjacent helices with opposite handedness can interlock into double helices with higher density, and urge each other extending to entire stem during moving along opposite directions with the help of chain slipping, resulting in ordered arrangement of helical stems. Afterwards, single-chain clusters coalesce, leading to interchain crystalline ordering. The new model is helpful to understand the phenomena related to mesomorphic iPP.