Small-angle X-ray Diffraction Research Articles

Abstract P417: Cardiomyopathy-associated Variant In Troponin T Tail Domain Promotes Disruption Of Both Frank-starling Mechanism And Cardiac Myofilament Performance

Missense variant Ile79Asn in human cardiac troponin T (HcTnT-I79N) tail region has been linked to familial hypertrophic cardiomyopathy (HCM), arrhythmia, and sudden cardiac death. It has been reported that inotropic stimulation with high extracellular Ca 2+ or isoproterenol led to diastolic dysfunction in both isolated and in vivo HcTnT-I79N mice hearts. Although HcTnT-I79N effects are acknowledged to be dependent on the inotropic state of the cardiac muscle, little is known about how this pathogenic variant affects the Frank-Starling law of the heart. To further investigate the functional and structural consequences of this deadly variant in a stretch-dependent manner, cardiac tissues were harvested from non-transgenic (NTg) control mice and transgenic mice bearing HcTnT-I79N. Left ventricular papillary muscle bundles were permeabilized and mounted for mechanical measurements. Sarcomere length (SL 1.9, 2.1 or 2.3 μm) was set at pCa 8 using HeNe laser diffraction and then Ca 2+ -dependence of isometric force, sinusoidal stiffness (SS, 0.2% PTP length oscillation) and rate of tension redevelopment ( k TR ) were measured. We observed that HcTnT-I79N tissue exhibited increased myofilament Ca 2+ -sensitivity of force, increased SS, slower k TR at all levels of Ca 2+ -activation, and diminished length-dependent activation (LDA). Small-angle X-ray diffraction revealed that HcTnT-I79N permeabilized cardiac muscles exhibit smaller myofilament lattice spacing at longer SLs (2.1 μm and 2.3 μm) compared to NTg. Using 3% Dextran T500 to osmotically compress the myofilament lattice (SL 2.1 μm), HcTnT-I79N showed no change in myofilament lattice spacing and little change in contractile indices associated with LDA. Interestingly, upon osmotic compression, HcTnT-I79N displayed a decrease in disordered relaxed state (DRX, ON state) of myosin and an increase in super-relaxed state (SRX, OFF state) of myosin. We conclude that altered cardiac myofilament performance, lack of responsiveness to osmotic compression, and reduced LDA observed with HcTnT-I79N are partially due to a combination of smaller myofilament lattice and disturbed ON and OFF states of myosin.

Cubic and Hexagonal Mesophases for Protein Encapsulation: Structural Effects of Insulin Confinement

Monoolein-based cubic and hexagonal mesophases were investigated as matrices for insulin loading, at low pH, as a function of temperature and in the presence of increasing amounts of oleic acid, as a structural stabilizer for the hexagonal phase. Synchrotron small angle X-ray diffraction, rheological measurements, and attenuated total reflection-Fourier transform infrared spectroscopy were used to study the effects of insulin loading on the lipid mesophases and of the effect of protein confinement in the 2D- and 3D-lipid matrix water channels on its stability and unfolding behavior. We found that insulin encapsulation has only little effects both on the mesophase structures and on the viscoelastic properties of lipid systems, whereas protein confinement affects the response of the secondary structure of insulin to thermal changes in a different manner according to the specific mesophase: in the cubic structure, the unfolding toward an unordered structure is favored, while the prevalence of parallel β-sheets, and nuclei for fibril formation, is observed in hexagonal structures.

Effect of Active Lengthening and Shortening on Small-Angle X-ray Reflections in Skinned Skeletal Muscle Fibres.

Our purpose was to use small-angle X-ray diffraction to investigate the structural changes within sarcomeres at steady-state isometric contraction following active lengthening and shortening, compared to purely isometric contractions performed at the same final lengths. We examined force, stiffness, and the 1,0 and 1,1 equatorial and M3 and M6 meridional reflections in skinned rabbit psoas bundles, at steady-state isometric contraction following active lengthening to a sarcomere length of 3.0 µm (15.4% initial bundle length at 7.7% bundle length/s), and active shortening to a sarcomere length of 2.6 µm (15.4% bundle length at 7.7% bundle length/s), and during purely isometric reference contractions at the corresponding sarcomere lengths. Compared to the reference contraction, the isometric contraction after active lengthening was associated with an increase in force (i.e., residual force enhancement) and M3 spacing, no change in stiffness and the intensity ratio I1,1/I1,0, and decreased lattice spacing and M3 intensity. Compared to the reference contraction, the isometric contraction after active shortening resulted in decreased force, stiffness, I1,1/I1,0, M3 and M6 spacings, and M3 intensity. This suggests that residual force enhancement is achieved without an increase in the proportion of attached cross-bridges, and that force depression is accompanied by a decrease in the proportion of attached cross-bridges. Furthermore, the steady-state isometric contraction following active lengthening and shortening is accompanied by an increase in cross-bridge dispersion and/or a change in the cross-bridge conformation compared to the reference contractions.

Structures, Electronic Properties, and Interactions of Cetyl Alcohol with Cetomacrogol and Water: Insights from Quantum Chemical Calculations and Experimental Investigations.

The complexes of cetyl alcohol, cetomacrogol-1000, and water were successfully synthesized. The complexes were characterized by freeze-drying scanning electron microscopy, small-angle X-ray diffraction (SAXD), and ultra-SAXD. Furthermore, structures, electronic properties (the HOMO–LUMO gap, ionization potential, electron affinity, electronegativity, hardness, softness, dipole moment, and polarizability), and Raman spectra of cetyl alcohol, cetomacrogol-1000, and their binary and ternary complexes with water were also studied using density functional theory. The calculated lengths of hydrophilic heads in the ternary complexes were in good agreement with SAXD data. The results indicated the existence of two types of interlamellar spacings between successive swollen bilayers (approximately 144 and 72 Å) when polyoxyethylene groups of cetomacrogol-1000 molecules were completely hydrated and stretched. Besides, in comparison with the monomers, the ternary complex of cetyl alcohol, cetomacrogol-1000, and water with the molecular ratio of 1:1:1 (cetyl-ceto-H2O-1 complex) had outstanding properties.

Structure and magnetic characterization of Sr-doped BiFeO3 prepared by sol–gel method

Multiferroic nanocrystalline Bi[Formula: see text]Sr[Formula: see text]FeO3 ([Formula: see text], 0.05, 0.1) samples were synthesized using the sol–gel method and characterized by powder X-ray diffraction, Mössbauer spectroscopy and SQUID system. The small-angle X-ray diffraction analysis showed that the sample underwent phase transition from rhombohedral to pseudo-cubic structure with the enhancement of Sr content. In addition, impurity peaks gradually diminished, indicating that content of impurities of samples reduced. Furthermore, it can be determined that there is only Fe[Formula: see text] in all the samples and impurity phase that existed in the samples was Bi[Formula: see text]FeO[Formula: see text] by fitting Mössbauer spectra. It is further confirmed that Bi[Formula: see text] Sr[Formula: see text]FeO3 samples were generated by oxygen vacancy equilibrium valence state when Sr[Formula: see text] ions replaced Bi[Formula: see text] ions. The change of quadrupole splitting indicated that a low concentration of Sr[Formula: see text] ions diffused homogeneously in the sample. Magnetization measurement showed that the magnetization of the sample increased gradually with the substitution of Bi[Formula: see text] by nonequivalent Sr[Formula: see text] ions, which can be ascribed to the decrease of grain size and the increase of oxygen vacancy and specific surface in the samples.

"Plurethosome" as Vesicular System for Cutaneous Administration of Mangiferin: Formulative Study and 3D Skin Tissue Evaluation.

Human skin is dramatically exposed to toxic pollutants such as ozone. To counteract the skin disorders induced by the air pollution, natural antioxidants such as mangiferin could be employed. A formulative study for the development of vesicular systems for mangiferin based on phosphatidylcholine and the block copolymer pluronic is described. Plurethosomes were designed for mangiferin transdermal administration and compared to ethosome and transethosome. Particularly, the effect of vesicle composition was investigated on size distribution, inner and outer morphology by photon correlation spectroscopy, small angle X-ray diffraction, and transmission electron microscopy. The potential of selected formulations as vehicles for mangiferin was studied, evaluating encapsulation efficiency and in vitro diffusion parameters by Franz cells. The mangiferin antioxidant capacity was verified by the 2,2-diphenyl-1-picrylhydrazyl assay. Vesicle size spanned between 200 and 550 nm, being influenced by phosphatidylcholine concentration and by the presence of polysorbate or pluronic. The vesicle supramolecular structure was multilamellar in the case of ethosome or plurethosome and unilamellar in the case of transethosome. A linear diffusion of mangiferin in the case of ethosome and transethosomes and a biphasic profile in the case of plurethosomes indicated the capability of multilamellar vesicles to retain the drug more efficaciously than the unilamellar ones. The antioxidant and anti-inflammatory potential effect of mangiferin against pollutants was evaluated on 3D human skin models exposed to O3. The protective effect exerted by plurethosomes and transethosomes suggests their possible application to enhance the cutaneous antioxidant defense status.

Efficient Activation of Coal Fly Ash for Silica and Alumina Leaches and the Dependence of Pb(II) Removal Capacity on the Crystallization Conditions of Al-MCM-41.

In this study, four different coal fly ashes (CFAs) were used as raw materials of silica and alumina for the preparation of the alumina-containing Mobil Composition of Matter No. 41 (Al-MCM-41) and the exploration of an activation strategy that is efficient and universal for various CFAs. Alkaline hydrothermal and alkaline fusion activations proceeded at different temperatures to determine the best treatment parameters. We controlled the pore structure and surface hydroxyl density of the CFA-derived Al-MCM-41 by changing the crystallization temperature and aging time. The products were characterized by small-angle X-ray diffraction, nitrogen isotherms, Fourier-transform infrared spectroscopy, 29Si silica magic-angle spinning nuclear magnetic resonance, and transmission electron microscopy, and they were then grafted with thiol groups to remove Pb(II) from aqueous solutions. This paper innovatively evaluates the CFA activation strategies using energy consumption analysis and determines the optimal activation methodology and parameters. This paper also unveils the effect of the crystallization condition of Al-MCM-41 on its subsequent Pb(II) removal capacity. The results show that the appropriate selection of crystallization parameters can considerably increase the removal capacity over Pb(II), providing a new path to tackle the ever-increasing concern of aquic heavy-metal pollution.

Morphologies and Structure of Brain Lipid Membrane Dispersions.

This study aims to explore the variety of previously unknown morphologies that brain lipids form in aqueous solutions. We study how these structures are dependent on cholesterol content, salt solution composition, and temperature. For this purpose, dispersions of porcine sphingomyelin with varying amounts of cholesterol as well as dispersions of porcine brain lipid extracts were investigated. We used cryo-TEM to investigate the dispersions at high-salt solution content together with small-angle (SAXD) and wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) for dispersions in the corresponding salt solution at high lipid content. Sphingomyelin forms multilamellar vesicles in large excess of aqueous salt solution. These vesicles appear as double rippled bilayers in the images and as split Bragg peaks in SAXD together with a very distinct lamellar phase pattern. These features disappear with increasing temperature, and addition of cholesterol as the WAXD data shows that the peak corresponding to the chain crystallinity disappears. The dispersions of sphingomyelin at high cholesterol content form large vesicular type of structures with smooth bilayers. The repeat distance of the lamellar phase depends on temperature, salt solution composition, and slightly with cholesterol content. The brain lipid extracts form large multilamellar vesicles often attached to assemblies of higher electron density. We think that this is probably an example of supra self-assembly with a multiple-layered vesicle surrounding an interior cubic microphase. This is challenging to resolve. DSC shows the presence of different kinds of water bound to the lipid aggregates as a function of the lipid content. Comparison with the effect of lithium, sodium, and calcium salts on the structural parameters of the sphingomyelin and the morphologies of brain lipid extract morphologies demonstrate that lithium has remarkable effects also at low content.

Diffusionless transformation of soft cubic superstructure from amorphous to simple cubic and body-centered cubic phases

In a narrow temperature window in going from the isotropic to highly chiral orders, cholesteric liquid crystals exhibit so-called blue phases, consisting of different morphologies of long, space-filling double twisted cylinders. Those of cubic spatial symmetry have attracted considerable attention in recent years as templates for soft photonic materials. The latter often requires the creation of monodomains of predefined orientation and size, but their engineering is complicated by a lack of comprehensive understanding of how blue phases nucleate and transform into each other at a submicrometer length scale. In this work, we accomplish this by intercepting nucleation processes at intermediate stages with fast cross-linking of a stabilizing polymer matrix. We reveal using transmission electron microscopy, synchrotron small-angle X-ray diffraction, and angle-resolved microspectroscopy that the grid of double-twisted cylinders undergoes highly coordinated, diffusionless transformations. In light of our findings, the implementation of several applications is discussed, such as temperature-switchable QR codes, micro-area lasing, and fabrication of blue phase liquid crystals with large domain sizes.

Discotic liquid crystals of transition metal complexes 58 : Novel phthalocyanine-based mesogenic monomers and polymers exhibiting spontaneous homeotropic alignment and helical tetragonal columnar structure

Two synthetizations of a novel series of phthalocyanine-based discotic liquid crystals substituted by a polymerizable group, acryloyl group or a norbornene group: 2-(12-acryloyloxydodecyloxy)-3-methoxy-9,10,16,17,23,24-hexakis (3,4-dialkoxyphenoxy)phthalocyaninato copper(II) [abbreviated as (n,12)PcCu(OCH[Formula: see text])(Acryloyl) (7: e ([Formula: see text] = 10), f ([Formula: see text] = 12), g ([Formula: see text] = 14))] and 2-(12-norborn-2-ene carbonyloxydodecyloxy)-3-methoxy-9,10,16,17,23,24-hexakis(3,4-dialkoxyphenoxy)-phthalocyaninato copper(II): [abbreviated as (n, 12)PcCu(OCH[Formula: see text])(Norb) (9e, f, g)]. Their liquid crystalline properties and homeotropic alignment were investigated using a polarizing microscope, a differential scanning calorimetry (DSC), and a temperature-variable X-ray diffractometer. As a result, each of the derivatives gave a Col[Formula: see text] mesophase in the higher temperature region, displaying perfect homeotropic alignment between the two glass plates. In order to obtain the thin film while keeping their homeotropic alignment at room temperature, attempts to polymerize the monomers, 7 and 9, in the Col[Formula: see text] phase showed homeotropic alignment. The polymerization of the acryloyl-substituted monomers (7) was not successful in any of the methods, whereas the polymerization of norbornene-substituted monomers (9) was quite successful by ring-opening metathesis polymerization with a Grubbs catalyst to obtain the novel polymers, poly-(n, 12)PcCu(OCH[Formula: see text])(Norb) (10e, f, g). Each of the polymers (10) were found to show a perfect homeotropic alignment from room temperature to ca. 200[Formula: see text]C of the decomposition temperature. Moreover, it was also revealed from temperature-variable small-angle X-ray diffraction studies that each of the polymers 10 showed a helical Col[Formula: see text] (helical tetragonal columnar) structure. The helical Col[Formula: see text] phase structure may be able for use in organic electroluminescent devices and solar cells in the future.

Sonochemical assisted preparation of ZnS–ZnO/MCM-41 based on blast furnace slag and electric arc furnace dust for Cr (VI) photoreduction

Iron/steel making industry is a weed that produces large quantities of slag and dust. The objective of the present study was to develop a procedure for obtaining and characterizing photocatalysts derived from this waste for chromium remediation. The MCM-41 was synthesized via sodium silicate (Na2SiO3) derived from Blast Furnace Slag (BFS), and ZnO and ZnS were synthesized based on zinc extracted from Electric Arc Furnace Dust (EAFD). Subsequently, ZnO/ZnS were sono-chemically loaded on the MCM-41 and were tested for the Cr (IV) photoreduction. The resultant ZnO, ZnS, MCM-41, and composites were characterized by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), N2adsorption–desorption isotherms, Fourier-transform infrared (FT-IR) spectrometry, Dynamic Light scattering, and Transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). A regular hexagonal structure of typical mesoporous MCM-41 had been proven by small-angle XRD, HRTEM, and N2 adsorption–desorption. The photoreduction activity of ZnS–ZnO/MCM-41 nanocomposite has obvious efficiency compared to ZnO and ZnO/MCM-41, achieving a 94% photoreduction of Cr (VI) in 180 min under UV irradiation. The slight activity loss after 4 cycles (84.7%) reveals the good photoreduction properties of catalysts. Based on these results, ZnS–ZnO/MCM-41 composite material seems to be high efficiency, green, stable, environment, and economical alternative to be used as a photocatalyst for the reduction of Cr (VI).

Synchrotron Microbeam Diffraction Studies on the Alignment within 3D-Printed Smectic-A Liquid Crystal Elastomer Filaments during Extrusion

3D printing of novel and smart materials has received considerable attention due to its applications within biological and medical fields, mostly as they can be used to print complex architectures and particular designs. However, the internal structure during 3D printing can be problematic to resolve. We present here how time-resolved synchrotron microbeam Small-Angle X-ray Diffraction (μ-SAXD) allows us to elucidate the local orientational structure of a liquid crystal elastomer-based printed scaffold. Most reported 3D-printed liquid crystal elastomers are mainly nematic; here, we present a Smectic-A 3D-printed liquid crystal elastomer that has previously been reported to promote cell proliferation and alignment. The data obtained on the 3D-printed filaments will provide insights into the internal structure of the liquid crystal elastomer for the future fabrication of liquid crystal elastomers as responsive and anisotropic 3D cell scaffolds.

Fast skeletal myosin-binding protein-C regulates fast skeletal muscle contraction

Fast skeletal myosin-binding protein-C (fMyBP-C) is one of three MyBP-C paralogs and is predominantly expressed in fast skeletal muscle. Mutations in the gene that encodes fMyBP-C, MYBPC2, are associated with distal arthrogryposis, while loss of fMyBP-C protein is associated with diseased muscle. However, the functional and structural roles of fMyBP-C in skeletal muscle remain unclear. To address this gap, we generated a homozygous fMyBP-C knockout mouse (C2-/-) and characterized it both in vivo and in vitro compared to wild-type mice. Ablation of fMyBP-C was benign in terms of muscle weight, fiber type, cross-sectional area, and sarcomere ultrastructure. However, grip strength and plantar flexor muscle strength were significantly decreased in C2-/- mice. Peak isometric tetanic force and isotonic speed of contraction were significantly reduced in isolated extensor digitorum longus (EDL) from C2-/- mice. Small-angle X-ray diffraction of C2-/- EDL muscle showed significantly increased equatorial intensity ratio during contraction, indicating a greater shift of myosin heads toward actin, while MLL4 layer line intensity was decreased at rest, indicating less ordered myosin heads. Interfilament lattice spacing increased significantly in C2-/- EDL muscle. Consistent with these findings, we observed a significant reduction of steady-state isometric force during Ca2+-activation, decreased myofilament calcium sensitivity, and sinusoidal stiffness in skinned EDL muscle fibers from C2-/- mice. Finally, C2-/- muscles displayed disruption of inflammatory and regenerative pathways, along with increased muscle damage upon mechanical overload. Together, our data suggest that fMyBP-C is essential for maximal speed and force of contraction, sarcomere integrity, and calcium sensitivity in fast-twitch muscle.

Ordered mesoporous carbons with body centred cubic pore structure

The preparation of mesoporous carbons possessing a highly ordered body centred cubic (bcc) arrangement of pores by employing a halide- and metal-free synthesis method is reported. Products were characterised using gas physisorption, Small Angle X-ray Diffraction and X-ray Scattering, Raman spectroscopy and High Resolution Transmission Electron Microscopy (TEM). The materials produced in this work had Specific Surface Areas of between 422 and 988 m2g−1 and pore diameters of around 7 nm. From the TEM images, high quality Digital Diffraction Patterns, relating to the ordered mesopore structure, were obtained. On increasing calcination temperature from 350 to 1000°C the bcc structure was retained but its dimensions decreased progressively as the mesopore structure shrank. The effects on the structure and texture of the materials of the three key parameters of polymerisation time and the concentrations of the two catalysts employed, NH4OH and oxalic acid, were studied. Shorter polymerisation times and lower catalyst concentrations gave rise to the most well-ordered products whereas longer polymerisation times with higher concentrations of base and acid catalyst resulted in disordered pore structures.

Thermosensitive Drug Delivery System SBA-15-PEI for Controlled Release of Nonsteroidal Anti-Inflammatory Drug Diclofenac Sodium Salt: A Comparative Study.

Mesoporous SBA-15 silica material was prepared by the sol–gel method and functionalized with thermosensitive polyethylenimine polymers with different molecular weight (g·mol−1): 800 (SBA-15(C)-800), 1300 (SBA-15(C)-1300) and 2000 (SBA-15(C)-2000). The nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium was selected as a model drug and encapsulated into the pores of prepared supports. Materials were characterized by the combination of infrared spectroscopy (IR), atomic force microscopy (AFM), transmission electron microscopy (TEM), photon cross-correlation spectroscopy (PCCS), nitrogen adsorption/desorption analysis, thermogravimetry (TG), differential scanning calorimetry (DSC) and small-angle X-ray diffraction (SA-XRD) experiments. The drug release from prepared matrixes was realized in two model media differing in pH, namely small intestine environment/simulated body fluid (pH = 7.4) and simulated gastric fluid (pH = 2), and at different temperatures, namely normal body temperature (T = 37 °C) and inflammatory temperature (T = 42 °C). The process of drug loading into the pores of prepared materials from the diclofenac sodium salt solutions with different concentrations and subsequent quantitative determination of released drugs was analyzed by UV-VIS spectroscopy. Analysis of prepared SBA-15 materials modified with polyethylenimines in solution showed a high ability to store large amounts of the drug, up to 230 wt.%. Experimental results showed their high drug release into the solution at pH = 7.4 for both temperatures, which is related to the high solubility of diclofenac sodium in a slightly alkaline environment. At pH = 2, a difference in drug release rate was observed between both temperatures. Indeed, at a higher temperature, the release rates and the amount of released drug were 2–3 times higher than those observed at a lower temperature. Different kinetic models were used to fit the obtained drug release data to determine the drug release rate and its release mechanism. Moreover, the drug release properties of prepared compounds were compared to a commercially available medicament under the same experimental conditions.

Effect of pH and temperature on the aggregation behaviour of dirhamnolipid biosurfactant. An experimental and molecular dynamics study

HypothesisPseudomonas aeruginosa dirhamnolipid (diRL) has been shown to form aggregates of different size and structure, under various conditions. Due to the presence of a carboxyl group in the molecule, it is expected that pH would strongly affect this aggregation behaviour. In addition, preliminary observations of temperature-induced changes in the states of aggregation of diRL supported the need of further investigation. ExperimentsA systematic experimental study, using differential scanning calorimetry (DSC), small-angle Xray diffraction (SAXD), and Fourier-transform infrared spectroscopy (FTIR), has been carried out to characterize pH and temperature driven changes in the aggregation behavior of diRL biosurfactant. Molecular dynamics (MD) simulations, supported by the experimental results, allowed depicting molecular details on formation of diRL membranes and other aggregated structures under various physicochemical conditions. FindingsDiRL could adopt fairly organized multilayered structures (membranes) at low pH and temperature, which became highly disordered upon increasing either of these parameters. The effect of pH on the gauche/all-trans conformer ratio of the diRL acyl chains was not of significance, whereas temperature-induced effects were observed. For the first time it is described that diRL underwent an endothermic thermotropic transition with Tc = 34 °C as observed by DSC, at pH 4.5 (protonated diRL), but not at pH 7.4 (unprotonated diRL). FTIR confirmed these findings, showing a significant additional disordering of the all-trans acyl chains upon increasing temperature around that same value in the protonated form, an effect not observed for the dissociated form of the biosurfactant. In addition, at pH 7.4, changing temperature did not modify the hydration state of the polar moiety of diRL, whereas at pH 4.5 a significant decrease in the hydration state around 34 °C took place. SAXD data showed that protonated diRL formed multilayered structures at 20 °C, which converted into poorly correlated layers at 50 °C. MD simulations supported these findings, showing that the membrane-like structures formed by protonated diRL at 20 °C became unstable at higher temperatures, tending to form other structures, which could be micelles or other type of layered structures, whereas the negatively charged form of diRL organized in micelle-type aggregates in the whole range of temperature under study.

Surface Functionalization of Doxorubicin loaded MCM-41 Mesoporous Silica Nanoparticles by 3-Aminopropyltriethoxysilane for Selective Anticancer 9 Effect on A549 and A549/DOX Cells

In this study, MCM-41 mesoporous silica nanoparticles were successfully synthesized by the condensation of a tetraorthosilicate precursor on a template self-assembled by cetyltrimethylammonium bromide in alkaline. The small-angle x-ray diffraction patterns of MCM-41 indicate that silica nanoparticles possess hexagonal structures with a high degree of structural ordering. Transmission electron microscopy images show that the size of the MCM-41 particles is around 100-120 nm, and the pore sizes range from 2 nm to 4 nm. In addition, the specific surface area of MCM-41 obtained by Brunauer–Emmett–Teller analysis is as high as 987 m2.g−1 and the pore size extracted from nitrogen physical adsorption isotherms is in accordance with the TEM result. Thermogravimetric analysis, Fourier-transform infrared spectroscopy, Zeta potential measurements and photoluminescence measurements show that 3-aminopropyltriethoxysilane (APTES) and doxorubicin were grafted and loaded successfully onto MCM-41 nanoparticles. An assay on fibroblasts, A549 and doxorubicin-resistant A549/DOX cells indicates that the prepared MCM41 grafting APTES nanoparticles are safe to normal cells and toxic to cancer cells in vitro.

A novel reactive P-containing composite with an ordered porous structure for suppressing nano-Al dust explosions

A novel chemical suppressant ([email protected]2-MCM41) was synthesized via self-assembly. NH2-MCM-41 was prepared using diatomaceous earth (DE) as the silica source. FTIR spectra showed that phytic acid (PA) was successfully grafted onto synthesized NH2-MCM-41 via hydrogen bonding. The highly ordered mesoporous structure of [email protected]2-MCM41 was observed from TEM and small angle X-ray diffraction (SAXRD). The effectiveness of [email protected]2-MCM41 in the suppression of nano-Al dust explosions was investigated. Experimental results suggested that the addition of [email protected]2-MCM41 could effectively reduce the average flame propagation velocity (Vavg) and maximum explosion pressure (Pmax). After the addition of 16.7 wt% [email protected]2-MCM41, the Vavg of the gas-phase flame was reduced by 75%. With addition of 28.6 wt% [email protected]2-MCM41, the Pmax of nano-Al dust decreased by 65.7%. As the mass fraction of [email protected]2-MCM41was increased to 33.3%, nano-Al dust explosion was completely suppressed. The SEM, FTIR and EDS results showed that a complex sealing film was formed on the surface of the explosion products, which occupied the open sites on the Al surface and thereby interrupted the Al evaporation and surface reaction. Subsequently, the suppression mechanism by which phosphorus containing suppressants consume free radicals and the interaction of PA molecules with the aluminum particle surface were revealed in depth.

Gelatin-loaded cubosomes stabilized with hydrophobically modified quaternized cellulose nanofiber and their pH-dependent release property.

Monoolein cubic phase immobilizing hydrophobically modified gelatin (HmGel) in its water channel was prepared by a melt-hydration method. The cubic phase was micronized into cubosomes by using hydrophobically modified quaternized cellulose nanofiber (HmQCNF) as a stabilizer. The phase transition temperature of the cubic phase was about 68-70 °C. Small angle X-ray diffraction revealed that HmGel-loaded cubosome stabilized with HmCNF was a diamond type of cubic phase. HmGel-loaded cubosomes stailized with HmQCNF were dependent on the pH value in terms of the release of their payload (i.e, methylene blue) much more strongly than HmGel-loaded cubosomes stabilized with Pluronic F127.

Understanding and Controlling the Crystallization Process in Reconfigurable Plasmonic Superlattices

The crystallization of nanomaterials is a primary source of solid-state, photonic structures. Thus, a detailed understanding of this process is of paramount importance for the successful application of photonic nanomaterials in emerging optoelectronic technologies. While colloidal crystallization has been thoroughly studied, for example, with advanced in situ electron microscopy methods, the noncolloidal crystallization (freezing) of nanoparticles (NPs) remains so far unexplored. To fill this gap, in this work, we present proof-of-principle experiments decoding a crystallization of reconfigurable assemblies of NPs at a solid state. The chosen material corresponds to an excellent testing bed, as it enables both in situ and ex situ investigation using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atomic force microscopy (AFM), and optical spectroscopy in visible and ultraviolet range (UV–vis) techniques. In particular, ensemble measurements with small-angle XRD highlighted the dependence of the correlation length in the NPs assemblies on the number of heating/cooling cycles and the rate of cooling. Ex situ TEM imaging further supported these results by revealing a dependence of domain size and structure on the sample preparation route and by showing we can control the domain size over 2 orders of magnitude. The application of HAADF-STEM tomography, combined with in situ thermal control, provided three-dimensional single-particle level information on the positional order evolution within assemblies. This combination of real and reciprocal space provides insightful information on the anisotropic, reversibly reconfigurable assemblies of NPs. TEM measurements also highlighted the importance of interfaces in the polydomain structure of nanoparticle solids, allowing us to understand experimentally observed differences in UV–vis extinction spectra of the differently prepared crystallites. Overall, the obtained results show that the combination of in situ heating HAADF-STEM tomography with XRD and ex situ TEM techniques is a powerful approach to study nanoparticle freezing processes and to reveal the crucial impact of disorder in the solid-state aggregates of NPs on their plasmonic properties.