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In this work, we prepared oriented mesoporous thin films of silica on various solid substrates using the pluronic block copolymer P123 as a template. We attempted to insert guest iron oxide (FexOy) nanoparticles into these films by two different methods: (a) by co-precipitation—where iron precursors are introduced in the synthesis sol before deposition of the silica film—and subsequent oxide production during the film calcination step; (b) by preparing and calcining the silica films first then impregnating them with the iron precursor, obtaining the iron oxide nanoparticles by a second calcination step. We have examined the structural effects of the guest nanoparticles on the silica film structures using grazing incidence X-ray scattering (GISAXS), high-resolution transmission electron spectroscopy (HRTEM), spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), and Raman microscopy. Formation of nanoparticles by co-precipitation may induce substantial changes in the film structure leading, in our adopted process, to the appearance of lamellar ordering in the calcination stage. On the contrary, impregnation-based approaches perturb the film structures much more weakly, but are also less efficient in filling the pores with nanoparticles. [ABSTRACT FROM AUTHOR]

Gene-based therapeutic approaches are based upon the concept that, if a disease is caused by a mutation in a gene, then adding back the wild-type gene should restore regular function and attenuate the disease phenotype. To deliver the gene of interest, both viral and nonviral vectors are used. Viruses are efficient, but their application is impeded by detrimental side-effects. Among nonviral vectors, cationic liposomes are the most promising candidates for gene delivery. They form stable complexes with polyanionic DNA (lipoplexes). Despite several advantages over viral vectors, the transfection efficiency (TE) of lipoplexes is too low compared with those of engineered viral vectors. This is due to lack of knowledge about the interactions between complexes and cellular components. Rational design of efficient lipoplexes therefore requires deeper comprehension of the interactions between the vector and the DNA as well as the cellular pathways and mechanisms involved. The importance of the lipoplex structure in biological function is revealed in the application of synchrotron small-angle X-ray scattering in combination with functional TE measurements. According to current understanding, the structure of lipoplexes can change upon interaction with cellular membranes and such changes affect the delivery efficiency. Recently, a correlation between the mechanism of gene release from complexes, the structure, and the physical and chemical parameters of the complexes has been established. Studies aimed at correlating structure and activity of lipoplexes are reviewed herein. This is a fundamental step towards rational design of highly efficient lipid gene vectors. [ABSTRACT FROM AUTHOR]

Abstract: The self-assembling of cationic liposomes (CLs) and DNA can give rise to a variety of nanostructures and morphologies. Multilamellar complexes are made of DNA intercalated between opposing lipid bilayers, while clusters formed by intact vesicles may exist as ‘beads-on-a-string’ (i.e. CLs attached to a string of DNA). Precise knowledge of the structure and morphology of complexes is relevant in many biological important processes such as gene delivery. Here dynamic light scattering, zeta potential, synchrotron small angle X-ray scattering and one-dimensional polyacrylamide gel electrophoresis were performed to investigate the equilibrium structure, morphology and interactions with plasma proteins of lipoplexes made of the cationic lipid (3β-[N-(N′,N′-dimethylaminoethane)-carbamoyl])-cholesterol (DC-Chol), the zwitterionic lipid dioleoylphosphatidylethanolamine (DOPE) and DNA. Results show that DC-Chol–DOPE/DNA complexes are multilamellar systems with DNA protected by cationic lipids. On the other hand, the ‘protein corona’ associated to lipoplexes after interaction with human plasma was found to be much richer in basic immunoglobulins gamma proteins (Ig-Gs) than that of pure lipid vesicles in the absence of DNA. According to the most recent evidences reported in the literature, this finding would suggest the existence of hybrid structures made of multilamellar complexes either stuck together by DNA or coexisting with DNA-loaded intact vesicles. Because surface properties of lipoplexes may determine their interaction with cells and tissues, these results may be important for predicting biological responses in vivo. [ABSTRACT FROM AUTHOR]

Using extensive state-of-the-art experiments over a wide range of synthesis parameters, such as the temperature and concentrations of different reactants, we establish qualitatively different growth kinetics for ZnO nanocrystals compared to all growth kinetics of semiconductor nanocrystals, including ZnO, discussed so far in the literature. The growth rate is shown to be strongly dependent on the concentration of (OH)- in an intriguing nonmonotonic manner as well as on temperature and is almost invariably much slower than well-known and generally accepted growth mechanisms based on a diffusion-controlled Ostwald ripening process or that expected in the surface reaction controlled regime. We show that these qualitatively different results arise from the unexpected role played by a part of the reactants by inhibiting rather than facilitating the reaction; we explain this extraordinary result in terms of an effective passivating layer around the growing nanocrystals formed by a virtual capping shell of Na+ ions. [ABSTRACT FROM AUTHOR]

Abstract: Effect of lipid hydration on the structure of lamellar lipoplexes made of the cationic lipid 3-[N-(N,N-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol), the neutral ‘helper’ lipid dioleoylphosphatidylethanolamine (DOPE) and calf-thymus DNA was investigated by synchrotron small angle X-ray diffraction (SAXD). Here, we show that lipid hydration is the key factor regulating the equilibrium structure of lipoplexes. Thermotropic behavior was also investigated between 5 and 65°C. Both the membrane thickness and the water layer thickness were found to decrease linearly as a function of temperature while the one dimensional DNA rod lattice between lipid bilayers was found to enlarge. Structural results were interpreted in terms of recently proposed theoretical models. [Copyright &y& Elsevier]

Abstract: Solid-supported lipid/DNA complexes were prepared by using highly aligned 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) multibilayers as a template. The complex formation was promoted in situ and followed in time. The resulting DOTAP/DNA complex shows a good degree of orientation along the normal to the support as revealed by combined time-resolved energy dispersive X-ray diffraction (EDXD) and surface synchrotron small angle X-ray scattering (SAXS) measurements. [Copyright &y& Elsevier]

Abstract: Investigations aimed at clarifying the nature of geometrical domains of amidic sodium N-dodecanoyl-l-prolinate are reported. NMR investigations on the association of aromatic solutes with the aggregates formed by the amidic surfactant in water show the selective binding of some solutes to the Z domains. Fluorescence quenching experiments allowed us to measure the aggregation number of the aggregates. SAXS experiments gave the average size and structural features of the aggregates. A NMR ROESY experiment evidenced the mosaic-like nature of the domains inside the same aggregate. [Copyright &y& Elsevier]

Abstract: In this work, we report on recent investigations, both on the global and on the local molecular architecture of supported phospholipid model membranes. A brief theoretical introduction explains how global structural information on supramolecular lipid ensembles can be retrieved from surface X-ray diffraction measurements as well as how spin-label electron paramagnetic resonance spectroscopy (EPR) provides complementary information on the local environment of probe molecules. The combination of especially designed X-ray cells with the technique of small- and wide-angle X-ray surface scattering makes it possible to explore various fields of lipid research and its applications. Examples for different physico-chemical conditions are presented: (i) in situ chemistry under excess of water conditions demonstrating how solid-supported lipid films sense salinity, (ii) the 3D electron density reconstruction of a vesicle-fusion intermediate under controlled humidity, and (iii) complementary temperature and pressure effects on oriented phospholipid samples. Further, special attention has been given to the influence of different film preparation techniques with respect to quality and the defect structure manifestation. To resolve the proportions and local properties of defects in a hydrated lipid-deposited surface, spin-label EPR was applied. The results from 9.6 GHz EPR as well as from 1.2 GHz EPR suggest the alignment to be in the range between 30% and 80%. In addition, slow time-dependent EPR measurements point to nano-structural rearrangements due to water flow and reduction of alignment quality. [Copyright &y& Elsevier]

[Display omitted] Understanding and manipulating the oil/water interface is important across various industries, including food, pharmaceuticals, cosmetics, and detergents. Many of these processes occur under elevated pH conditions in buffer systems, where base-catalyzed hydrolysis of triglyceride ester bonds leads to amphiphilic reaction products such as fatty acids. Here, pH-triggered alterations of the triolein/water interface are analyzed in the presence of phosphate (PB) and tris(hydroxymethyl)aminomethane (TRIS). Ellipsometry at the liquid/liquid interface, tensiometry, and scanning small angle X-ray scattering are used to study the formation of structures at the oil/water interface. Confocal Raman microscopy, nuclear magnetic resonance spectroscopy, and in silico modeling analyze compositional changes in the interfacial region. pH and buffer ions were discovered to significantly modify the triglyceride/water interface, contrary to the decane/water control. Decreasing interfacial tensions from 32.4 to 2.2 mN/m upon pH increase from 6.5 to 9.5 is seen with multilamellar interfacial layers forming at pH around 9.0 in the presence of TRIS. Oleic acid from triolein hydrolysis and its further interaction with TRIS is held responsible for this. The new understanding can guide the design of pH- and ion-responsive functional materials and optimize industrial processes involving triglyceride/water interfaces. [ABSTRACT FROM AUTHOR]

When drying a colloidal solution, cracks appear in the resulting colloidal film. In certain cases, spontaneous order is observed, and cracks form arrays of periodic patterns. Although this phenomenon might be envisioned as a patterning method, overcoming practical challenges is necessary to transform it into a technological tool for microfabrication. This study explores various technological aspects aimed at leveraging the self‐assembly of cracks as a scalable microfabrication tool for large‐scale device production. Through a series of analyses, including time‐resolved Grazing‐Incidence Small‐Angle X‐Ray Scattering (GISAXS), it is offered novel insights into controlling the crack self‐ordering mechanism, minimizing defects, and implementing strategies for large‐scale patterning and pattern transfer. The process proves to be surprisingly robust, maintaining its efficacy with the same colloidal solution even after two years. By introducing biphasic dip‐coating, large‐scale crack patterns up to 100 cm2, while preserving their periodicity and ordering is achieved. As a proof of concept, the use of crack‐patterned colloidal films as masks for fabricating metallic sub‐micrometer objects, that serve as transparent electrodes with adjustable transparency and conductivity is showcased. Overall, this method presents significant advantages over conventional lithography, being cost‐effective, versatile, environmentally friendly, and scalable, thereby offering new perspectives for diverse applications requiring cost‐effective and large‐scale patterning. [ABSTRACT FROM AUTHOR]

Lipid nanoparticles own a remarkable potential in nanomedicine, only partially disclosed. While the clinical use of liposomes and cationic lipid-nucleic acid complexes is well-established, liquid lipid nanoparticles (nanoemulsions), solid lipid nanoparticles, and nanostructured lipid carriers have even greater possibilities. However, they face obstacles in being used in clinics due to a lack of understanding about the molecular mechanisms controlling their drug loading and release, interactions with the biological environment (such as the protein corona), and shelf-life stability. To create effective drug delivery carriers and successfully translate bench research to clinical settings, it is crucial to have a thorough understanding of the internal structure of lipid nanoparticles. Through synchrotron small-angle X-ray scattering experiments, we determined the spatial distribution and internal structure of the nanoparticles' lipid, surfactant, and the bound water in them. The nanoparticles themselves have a barrel-like shape that consists of coplanar lipid platelets (specifically cetyl palmitate) that are covered by loosely spaced polysorbate 80 surfactant molecules, whose polar heads retain a large amount of bound water. To reduce the interface cost of bound water with unbound water without stacking, the platelets collapse onto each other. This internal structure challenges the classical core-shell model typically used to describe solid lipid nanoparticles and could play a significant role in drug loading and release, biological fluid interaction, and nanoparticle stability, making our findings valuable for the rational design of lipid-based nanoparticles. [ABSTRACT FROM AUTHOR]

Controlling the magnitude of structural dynamics in flexible MOF films by an applied stimulus is largely desired for specific applications such as energy storage. Herein, by introducing chlorine substituents in an azobenzene-infiltrated Cl-DMOF-1 film structure, a significantly slowed structural response is obtained upon photo-switching of the system. [ABSTRACT FROM AUTHOR]

[Display omitted] Renal calculi (kidney stones) are mainly made by calcium oxalate and can cause different complications including malfunction of the kidney. The most important urinary stone inhibitors are citrate molecules. Unfortunately, the amount of citrate reaching the kidney after oral ingestion is low. We hypothesized that nanoparticles of polyallylamine hydrochloride (CIT-PAH) carrying citrate ions could simultaneously deliver citrates while PAH would complex oxalate triggering dissolution and removal of CaOx nanocrystals. We successfully prepared nanoparticles of citrate ions with polyallylamine hydrochloride (CIT-PAH), PAH with oxalate (OX-PAH) and characterize them by Small Angle X ray Scattering (SAXS), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and NMR. Dissolution of CaOx nanocrystals in presence of CIT-PAH have been followed with Wide Angle Xray Scattering (WAXS), DLS and Confocal Raman Microscopy. Raman spectroscopy was used to study the dissolution of crystals in synthetic urine samples. The release of citrate from CIT-PAH was followed by diffusion NMR. Molecular dynamics (MD) simulations were carried out to study the interaction of CIT and OX ions with PAH. CIT-PAH nanoparticles dissolves CaOx nanocrystals as shown by NMR, DLS, TEM and WAXS in water and by Raman spectroscopy in artificial human urine. WAXS and Raman show that the crystal structure of CaOx disappears in the presence of CIT-PAH. DLS shows that the time required for CaOX dissolution will depend on the concentration of CIT-PAH NPs. NMR proves that citrate ions are released from the CIT PAH NPs during CaOX dissolution, MD simulations showed that oxalates exhibit a stronger interaction for PAH than citrate, explaining the removal of oxalate ions and replacement of the citrate in the polymer nanoparticles. [ABSTRACT FROM AUTHOR]

X-ray diffraction using micro- and nanofocused beams is well suited for nanostructure analysis at different sites of a biological micro-object. To conduct in vitro studies without mechanical contact, we developed object manipulation by optical tweezers in a microfluidic cell. Here we report x-ray microdiffraction analysis of a micro-object optically trapped in three dimensions. We revealed the nanostructure of a single starch granule at different points and investigated local radiation damage induced by repeated x-ray exposures at the same position, demonstrating high stability and full control of the granule orientation by multiple optical traps. [ABSTRACT FROM AUTHOR]

Synchrotron small angle x-ray scattering and electrophoresis on agarose gels have been applied to construct the phase diagram of the ternary complex made up of the cationic lipid 3β-[N-(N,N-dimethylaminoethane)-carbamoyl]-cholesterol, the neutral lipid dioleoylphosphatidylethanolamine and DNA. We show that nominally charge-neutral complexes coexist with free DNA, while excess cationic charge is necessary to protect all the genetic cargo. Such an extra-charge requirement diminishes as the molar fraction of neutral lipid in the bilayer increases. Furthermore, complexes with very different membrane composition and charge ratio exhibit the very same DNA protection ability. The relevance of results for transfection studies is discussed. [ABSTRACT FROM AUTHOR]

This work focuses on the interaction of the novel and representative antituberculosis (anti-TB) drug bedaquiline (BDQ) with different membrane models of eukaryotic and prokaryotic cells. The effect of BDQ on eukaryotic cell membrane models was assessed using liposomes, namely, multilamellar vesicles (MLVs) made of 1,2-dimyristoyl-rac-glycero-3-phosphocholine (DMPC) and also a mixture of DMPC and cholesterol (CHOL) (8:2 molar ratio). To mimic the prokaryotic cell membrane, 1,2-dimyristoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DMPG) and 1,1′2,2′-tetra-oleoyl-cardiolipin (TOCL) were chosen. Powerful biophysical techniques were employed, including small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), to understand the effect of BDQ on the nanostructure of the membrane models. The results showed that BDQ demonstrated a pronounced disordering effect in the bacterial cell membrane models, especially in the membrane model with cardiolipin (CL), while the human cell membrane model with large fractions of neutral phospholipids remained less affected. The membrane models and techniques provide detailed information about different aspects of the drug–membrane interaction, thus offering valuable information to better understand the effect of BDQ on their target membrane-associated enzyme as well as its side effects on the cardiovascular system. [ABSTRACT FROM AUTHOR]

Detailed multi-technique characterization of catalyst layer degradation is fundamental for improving catalyst stability and performances in Proton Exchange Membrane Fuel Cells (PEMFCs), and Small Angle X-Ray Scattering (SAXS) coupled to chemical and/or electrochemical analysis can provide important insights of processes involved in catalyst coarsening. In this extent, we present an approach to SAXS analysis able to describe all of the layers composing the Membrane Electrode Assembly (MEA): electrolyte, catalyst support, catalyst nanoparticles, and gas diffusion layers. This approach was used to compare morphological evolution of small clusters formed by catalyst nanoparticles in pristine and aged MEAs in both ex situ and in operando conditions, on a standard SAXS beamline, without exploiting the advantages of anomalous SAXS. Twin MEAs were aged with two different types of Accelerated Stress Tests (AST): one addressed to the catalyst support (s-AST) and one targeting the catalyst layer (c-AST). Limited growth of catalyst nanoparticle size was found when running s-AST, while remarkable evolution was revealed once applying c-AST. Such a difference was mainly reconducted to the disconnection of catalyst nanoparticles from the electrical paths, as supported by analysis of specific Electrochemically Active Surface Area (ECSA). In both cases, the small clusters were found becoming more compact after AST were run. [Display omitted] • An approach to investigate catalyst degradation via X-Ray scattering is presented. • The model was validated by coupling small angle scattering and electrochemistry. • The model was validated in both ex situ and in operando measurements. • Catalyst degradation was depicted depending on two different stress tests. [ABSTRACT FROM AUTHOR]

Molecular structure engineering has proved to be an efficient strategy to modify the properties of photoactive materials for organic solar cells. Several studies focused on the halogenation of donor and acceptor molecules, in order to tune the energy levels, the absorption properties or the molecular packing of the materials. In particular, bromination of small-molecule acceptors increases the film crystallinity of the bulk heterojunction, leading to higher charge carrier mobilities, and therefore, to a more efficient charge transport. In this study, we synthesized a mono-brominated non-fullerene acceptor derived from end-group modification of the M3 acceptor. This material showed slightly higher energy levels than M3 and a higher π–π stacking distance due to the larger size of bromine atoms compared to the fluorine atoms in M3. In addition, a second acceptor with non-halogenated rhodanine-based end groups was synthesized and investigated. While solar cells based on the latter NFA only showed negligible efficiencies, solar cells fabricated with the mono-brominated acceptor C1 and the conjugated polymer PM6 revealed power conversion efficiencies up to 11.6%. [ABSTRACT FROM AUTHOR]

Organic solar cells have been continuously studied and developed through the last decades. A major step in their development was the introduction of fused‐ring non‐fullerene electron acceptors. Yet, beside their high efficiency, they suffer from complex synthesis and stability issues. Perylene‐based non‐fullerene acceptors, in contrast, can be prepared in only a few steps and display good photochemical and thermal stability. Herein, we introduce four monomeric perylene diimide acceptors obtained in a three‐step synthesis. In these molecules, the semimetals silicon and germanium were added in the bay position, on one or both sides of the molecules, resulting in asymmetric and symmetric compounds with a red‐shifted absorption compared to unsubstituted perylene diimide. Introducing two germanium atoms improved the crystallinity and charge carrier mobility in the blend with the conjugated polymer PM6. In addition, charge carrier separation is significantly influenced by the high crystallinity of this blend, as shown by transient absorption spectroscopy. As a result, the solar cells reached a power conversion efficiency of 5.38 %, which is one of the highest efficiencies of monomeric perylene diimide‐based solar cells recorded to date. [ABSTRACT FROM AUTHOR]

[Display omitted] Modification of polyallylamine hydrochloride (PAH) with heterobifunctional low molecular weight polyethylene glycol (PEG) (600 and 1395 Da), and subsequent attachment of mannose, glucose, or lactose sugars to PEG, can lead to formation of polyamine phosphate nanoparticles (PANs) with lectin binding affinity and narrow size distribution. Size, polydispersity, and internal structure of glycosylated PEGylated PANs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). Fluorescence correlation spectroscopy (FCS) was used to study the association of labelled glycol-PEGylated PANs. The number of polymer chains forming the nanoparticles was determined from the changes in amplitude of the cross-correlation function of the polymers after formation of the nanoparticles. SAXS and fluorescence cross-correlation spectroscopy were used to investigate the interaction of PANs with lectins: concanavalin A with mannose modified PANs, and jacalin with lactose modified ones. Glyco-PEGylated PANs are highly monodispersed, with diameters of a few tens of nanometers and low charge, and a structure corresponding to spheres with Gaussian chains. FCS shows that the PANs are single chain nanoparticles or formed by two polymer chains. Concanavalin A and jacalin show specific interactions for the glyco-PEGylated PANs with higher affinity than bovine serum albumin. [ABSTRACT FROM AUTHOR]

Understanding and control of thermal transport in solids at the nanoscale are crucial in engineering and enhance the properties of a new generation of optoelectronic, thermoelectric and photonic devices. In this regard, semiconductor superlattice structures provide a unique platform to study phenomena associated with phonon propagations in solids such as heat conduction. Transient X‐ray diffraction can directly probe atomic motions and therefore is among the rare techniques sensitive to phonon dynamics in condensed matter. Here, optically induced transient heat conduction in GaAs/AlAs superlattice structures is studied using the EIGER2 detector. Benchmark experiments have been performed at the Austrian SAXS beamline at Elettra–Sincrotrone Trieste operated in the hybrid filling mode. This work demonstrates that drifts of experimental conditions, such as synchrotron beam fluctuations, become less essential when utilizing the EIGER2 double‐gating mode which results in a faster acquisition of high‐quality data and facilitates data analysis and data interpretation. [ABSTRACT FROM AUTHOR]

The ability to utilize a hybrid-photon-counting detector to its full potential can significantly influence data quality, data collection speed, as well as development of elaborate data acquisition schemes. This paper facilitates the optimal use of EIGER2 detectors by providing theory and practical advice on (i) the relation between detector design, technical specifications and operating modes, (ii) the use of corrections and calibrations, and (iii) new acquisition features: a doublegating mode, 8-bit readout mode for increasing temporal resolution, and lines region-of-interest readout mode for frame rates up to 98 kHz. Examples of the implementation and application of EIGER2 at several synchrotron sources (ESRF, PETRA III/DESY, ELETTRA, AS/ANSTO) are presented: high accuracy of high-throughput data in serial crystallography using hard X-rays; suppressing higher harmonics of undulator radiation, improving peak shapes, increasing data collection speed in powder X-ray diffraction; faster ptychography scans; and cleaner and faster pump-and-probe experiments. [ABSTRACT FROM AUTHOR]

In situ small‐angle X‐ray scattering (SAXS) was employed to identify critical parameters during thermal treatment for template removal of an ordered mesoporous carbon precursor synthesized via a direct soft‐templating route. The structural parameters obtained from the SAXS data as a function of time were the lattice parameter of the 2D hexagonal structure, the diameter of the cylindrical mesostructures and a power‐law exponent characterizing the interface roughness. Moreover, detailed information on contrast changes and pore lattice order was obtained from analysis of the integrated SAXS intensity of the Bragg and diffuse scattering separately. Five characteristic regions during heat treatment were identified and discussed regarding the underlying dominant processes. The influence of temperature and O2/N2 ratio on the final structure was analyzed, and parameter ranges were identified for an optimized template removal without strongly affecting the matrix. The results indicate that the final structure and controllability of the process are optimum for temperatures between 260 and 300°C with a gas flow containing 2 mol% of O2. [ABSTRACT FROM AUTHOR]

DNA origami objects allow for accurate positioning of guest molecules in three dimensions. Validation and understanding of design strategies for particle attachment as well as analysis of specific particle arrangements are desirable. Small-angle X-ray scattering (SAXS) is suited to probe distances of nano-objects with subnanometer resolution at physiologically relevant conditions including pH and salt and at varying temperatures. Here, we show that the pair density distribution function (PDDF) obtained from an indirect Fourier transform of SAXS intensities in a model-free way allows to investigate prototypical DNA origami-mediated gold nanoparticle (AuNP) assemblies. We analyze the structure of three AuNP-dimers on a DNA origami block, an AuNP trimer constituted by those dimers, and a helical arrangement of nine AuNPs on a DNA origami cylinder. For the dimers, we compare the model-free PDDF and explicit modeling of the SAXS intensity data by superposition of scattering intensities of the scattering objects. The PDDF of the trimer is verified to be a superposition of its dimeric contributions, that is, here AuNP-DNA origami assemblies were used as test boards underlining the validity of the PDDF analysis beyond pairs of AuNPs. We obtain information about AuNP distances with an uncertainty margin of 1.2 nm. This readout accuracy in turn can be used for high precision placement of AuNP by careful design of the AuNP attachment sites on the DNA-structure and by fine-tuning of the connector types. [ABSTRACT FROM AUTHOR]

Recent studies demonstrated the potential therapeutic use of newly synthesized omega-3 (ω-3) polyunsaturated fatty acid (PUFA) monoglycerides owing to their beneficial health effects in various disorders including cancer and inflammation diseases. To date, the research was mainly focused on exploring the biological effects of these functional lipids. However, to the best of our knowledge, there is no report on the hydration-mediated self assembly of these lipids that leads to the formation of nanostructures, which are attractive for use as vehicles for the delivery of drugs and functional foods. In the present study, we investigated the temperature-composition phase behaviour of eicosapentaenoic acid monoglyceride (MAG-EPA), which is one of the most investigated ω-3 PUFA monoglycerides, during a heating-cooling cycle in the temperature range of 5-60 °C. Experimental synchrotron small-angle X-ray scattering (SAXS) evidence on the formation of a dominant inverse hexagonal (H2) lyotropic liquid crystalline phase and its temperature-induced transition to an inverse micellar solution (L2 phase) is presented for the fully hydrated bulk MAG-EPA system and its corresponding dispersion. We produced colloidal MAG-EPA hexosomes with an internal inverse hexagonal (H2) lyotropic crystalline phase in the presence of F127, a well-known polymeric stabilizer, or citrem, which is a negatively charged food-grade emulsifier. In this work, we report also on the formation of MAG-EPA hexosomes by vortexing MAG-EPA in excess aqueous medium containing F127 at room temperature. This low-energy emulsification method is different than most reported studies in the literature that have demonstrated the need for using a high-energy input during the emulsification step or adding an organic solvent for the formation of such colloidal nonlamellar liquid crystalline dispersions. The designed nanoparticles hold promise for future drug and functional food delivery applications due to their unique structural properties and the potential health-promoting effects of MAG-EPA. [ABSTRACT FROM AUTHOR]

The colloidal structures formed during lipolysis of self-emulsifying drug delivery systems (SEDDS) might affect the solubilisation and possibly the absorption of drugs. The aim of the current study is to elucidate the structures formed during the in vitro lipolysis of four SEDDS containing medium-chain glycerides and caprylocaproyl polyoxyl-8 glycerides (Labrasol), with or without monoacyl phosphatidylcholine (MAPC). In situ synchrotron small-angle X-ray scattering (SAXS) was combined with ex situ cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) to elucidate the generated structures. The SAXS scattering curves obtained during the lipolysis of MAPC-free SEDDS containing 43–60% w/w Labrasol displayed a lamellar phase peak at q = 2.13 nm − 1 that increased with Labrasol concentration, suggesting the presence of multilamellar structures (MLS) with a d-spacing of 2.95 nm. However, SEDDS containing 20–30% w/w MAPC did not form MLS during the lipolysis. The cryo-TEM and DLS studies showed that MAPC-free SEDDS formed coarse emulsions while MAPC-containing SEDDS formed nanoemulsions during the dispersion in digestion medium. From the first minute and during the entire lipolysis process, SEDDS both with and without MAPC generated uni-, bi-, and oligo-lamellar vesicles. The lipolysis kinetics in the first minutes of the four SEDDS correlated with an increased intensity of the SAXS curves and the rapid transformation from lipid droplets to vesicles observed by cryo-TEM. In conclusion, the study elucidates the structures formed during in vitro lipolysis of SEDDS and the inhibitory effect of MAPC on the formation of MLS. [ABSTRACT FROM AUTHOR]

The aggregation of a water soluble, dicationic perylene bisimide derivative was studied by means of absorption and emission spectroscopies, X-ray and neutron scattering techniques as well as electron microscopy. The results provide evidence for the existence of higher order molecular aggregates in solution, potentially utilizable in device fabrication as super molecular building blocks. [ABSTRACT FROM AUTHOR]

This study investigates the effect of monoacyl phospholipid incorporation on the in vitro and in vivo performance of self-emulsifying drug delivery systems (SEDDS). Monoacyl phosphatidylcholine (Lipoid S LPC 80 (LPC)) was incorporated into four different fenofibrate (FF)-loaded long-chain SEDDS to investigate the impact of LPC on the emulsion droplet size, extent of digestion, colloidal structure evolution and drug precipitation during in vitro lipolysis simulating human conditions and drug bioavailability in a rat model. The four investigated SEDDS containing long-chain glycerides, polyoxyl 35 castor oil or polyoxyl 8 caprylocaproyl glycerides with or without LPC. In situ synchrotron small/wide-angle X-ray scattering (SAXS/WAXS) was used to simultaneously real-time monitor the kinetics of lamellar phase structure development and FF crystalline precipitation. Adding LPC increased the particle size and polydispersity of the dispersed SEDDS. The two LPC-free SEDDS generated lamellar phase structures (Lα) with d-spacing = 4.76 nm during digestion. Incorporating LPC into these systems inhibited the formation of lamellar phase structures. The amount of precipitated crystalline FF from the four SEDDS was similar during the first 15 min but differed during the last 45 min of in vitro digestion. The kinetics of colloidal structure development and FF precipitation was related to the digestion kinetics. The in vivo bioavailability data showed no significant differences between the four SEDDS, which correlates with the in vitro FF precipitation during the first 15 min of lipolysis. Thus, the presence of LPC, different emulsion droplet sizes and concentration of lamellar phase structures observed in vitro did not correlate with the FF absorption in rats. The study suggests that later time points of the in vitro lipolysis overestimated FF precipitation in rats because of the high enzyme activity, the lack of gastric and absorption steps, and the low bile salts and phospholipid concentrations of the in vitro model. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for Bi 2 S 3 and trimethylsilyl cellulose (TMSC) for cellulose. Solutions of these precursors were spin coated onto solid substrates yielding homogeneous precursor films. Afterwards, a heating step under inert atmosphere led to the formation of thin nanocomposite films of bismuth sulfide nanoparticles within the TMSC matrix. In a second step, the silyl groups were cleaved off by vapors of HCl yielding bismuth sulfide/cellulose nanocomposite films. The thin films were characterized by a wide range of surface sensitive techniques such as atomic force microscopy, attenuated total reflection infrared spectroscopy, transmission electron microscopy and wettability investigations. In addition, the formation of the nanoparticle directly in the TMSC matrix was investigated in situ by GI-SWAXS using a temperature controlled sample stage. [ABSTRACT FROM AUTHOR]

Resveratrol belongs to the large group of biologically active polyphenol compounds, with several beneficial health effects including antioxidant activity, anti-inflammatory action, cardiovascular protection, neuroprotection, and cancer chemoprevention. In the present study, the possibility that the effects of resveratrol described above are caused by resveratrol membrane interactions and structural modifications of lipid bilayers is evaluated. In this context, it is possible that resveratrol interacts selectively with lipid domains present in biological membranes, thereby modulating the localization of the anchored proteins and controlling their intracellular cascades. This study was conducted in a synchrotron particle accelerator, where the influence of resveratrol in the structural organization of lipid domains in bilayers was investigated using small- and wide-angle X-ray scattering (SAXS and WAXS) techniques. Membrane mimetic systems composed of egg l-α-phosphatidylcholine (EPC), cholesterol (CHOL), and sphingomyelin (SM), with different molar ratios, were used to access the effects of resveratrol on the order and structure of the membrane. The results revealed that resveratrol induces phase separation, promoting the formation of lipid domains in EPC, EPC:CHOL [4:1], and EPC:CHOL:SM [1:1:1] bilayers, which brings some structural organization to membranes. Therefore, resveratrol controls lipid packing of bilayers by inducing the organization of lipid rafts. Moreover, the formation of lipid domains is important for modulating the activity of many receptors, transmembrane proteins, and enzymes whose activity depends on the structural organization of the membrane and on the presence or absence of these organized domains. This evidence can thereby explain the therapeutic effects of resveratrol. [ABSTRACT FROM AUTHOR]

This work describes the design and synthesis of a π‐conjugated telluro[3,2‐β][1]‐tellurophene‐based synthon that, embodying pyridyl and haloaryl chalcogen‐bonding acceptors, self‐assembles into nanoribbons through chalcogen bonds. The ribbons π‐stack in a multi‐layered architecture both in single crystals and thin films. Theoretical studies of the electronic states of chalcogen‐bonded material showed the presence of a local charge density between Te and N atoms. OTFT‐based charge transport measurements showed hole‐transport properties for this material. Its integration as a p‐type semiconductor in multi‐layered CuI‐based light‐emitting electrochemical cells (LECs) led to a 10‐fold increase in stability (38 h vs. 3 h) compared to single‐layered devices. Finally, using the reference tellurotellurophene congener bearing a C−H group instead of the pyridyl N atom, a herringbone solid‐state assembly is formed without charge transport features, resulting in LECs with poor stabilities (<1 h). [ABSTRACT FROM AUTHOR]

This work describes the design and synthesis of a π‐conjugated telluro[3,2‐β][1]‐tellurophene‐based synthon that, embodying pyridyl and haloaryl chalcogen‐bonding acceptors, self‐assembles into nanoribbons through chalcogen bonds. The ribbons π‐stack in a multi‐layered architecture both in single crystals and thin films. Theoretical studies of the electronic states of chalcogen‐bonded material showed the presence of a local charge density between Te and N atoms. OTFT‐based charge transport measurements showed hole‐transport properties for this material. Its integration as a p‐type semiconductor in multi‐layered CuI‐based light‐emitting electrochemical cells (LECs) led to a 10‐fold increase in stability (38 h vs. 3 h) compared to single‐layered devices. Finally, using the reference tellurotellurophene congener bearing a C−H group instead of the pyridyl N atom, a herringbone solid‐state assembly is formed without charge transport features, resulting in LECs with poor stabilities (<1 h). [ABSTRACT FROM AUTHOR]

DNA vaccination has been extensively studied as a promising strategy for tumor treatment. Despite the efforts, the therapeutic efficacy of DNA vaccines has been limited by their intrinsic poor cellular internalization. Electroporation, which is based on the application of a controlled electric field to enhance DNA penetration into cells, has been the method of choice to produce acceptable levels of gene transfer in vivo. However, this method may cause cell damage or rupture, non-specific targeting, and even degradation of pDNA. Skin irritation, muscle contractions, pain, alterations in skin structure, and irreversible cell damage have been frequently reported. To overcome these limitations, in this work, we use a microfluidic platform to generate DNA-loaded lipid nanoparticles (LNPs) which are then characterized by a combination of dynamic light scattering (DLS), synchrotron small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Despite the clinical successes obtained by LNPs for mRNA and siRNA delivery, little is known about LNPs encapsulating bulkier DNA molecules, the clinical application of which remains challenging. For in vitro screening, LNPs were administered to human embryonic kidney 293 (HEK-293) and Chinese hamster ovary (CHO) cell lines and ranked for their transfection efficiency (TE) and cytotoxicity. The LNP formulation exhibiting the highest TE and the lowest cytotoxicity was then tested for the delivery of the DNA vaccine pVAX-hECTM targeting the human neoantigen HER2, an oncoprotein overexpressed in several cancer types. Using fluorescence-activated cell sorting (FACS), immunofluorescence assays and fluorescence confocal microscopy (FCS), we proved that pVAX-hECTM-loaded LNPs produce massive expression of the HER2 antigen on the cell membrane of HEK-293 cells. Our results provide new insights into the structure–activity relationship of DNA-loaded LNPs and pave the way for the access of this gene delivery technology to preclinical studies. [ABSTRACT FROM AUTHOR]

Hydrophobic organic compounds dissolved in a polar solvent can self-assemble into nanoparticles (NPs) upon nanoprecipitation into water. In the present study, we have investigated the structure of squalenacetyl-adenosine (SQAc-Ad) nanoparticles which were previously found to exhibit impressive neuroprotective activity. When obtained by nanoprecipitation of a SQAc-Ad ethanolic solution into water, two different supramolecular organizations of SQAc-Ad NPs were evidenced, depending on the water-to-ethanol volume ratio. It has been shown that a fraction of the solvent remained associated with the NPs, despite prolonged evaporation under reduced pressure after nanoprecipitation, and that this residual solvent dramatically affected their structure. This study points to the importance of being in the “Ouzo” region to minimize the amount and effect of residual solvent and to control the structure of NPs. [ABSTRACT FROM AUTHOR]

In situ small‐ and wide‐angle scattering experiments at synchrotrons often result in massive quantities of data within just seconds. Especially during such beamtimes, processing of the acquired data online, without appreciable delay, is key to obtaining feedback on the failure or success of the experiment. This had led to the development of SAXSDOG, a Python‐based environment for real‐time azimuthal integration of large‐area scattering images. The software is primarily designed for dedicated data pipelines: once a scattering image is transferred from the detector onto the storage unit, it is automatically integrated and pre‐evaluated using integral parameters within milliseconds. The control and configuration of the underlying server‐based processes is achieved via a graphical user interface, SAXSLEASH, which visualizes the resulting 1D data together with integral classifiers in real time. SAXSDOG further includes a portable 'take‐home' version for users that runs on standalone computers, enabling its use in laboratories or at the preferred workspace. [ABSTRACT FROM AUTHOR]

The full knowledge of the charge storage mechanisms occurring in complex composite electrodes is key for the straightforward development of advanced electrochemical capacitors. In this work, hybrid electrodes composed of reduced graphene oxide, multiwall carbon nanotubes and NiO nanostructures were fabricated through reactive inverse matrix assisted pulsed laser evaporation technique. Nitrogen doping of the carbon nanostructures was carried out by introducing ammonia, urea and melamine precursors in the target. The N-doped graphene electrodes exhibited a significant capacitance enhancement as compared to non-doped ones. This fact is commonly ascribed to faradaic mechanisms. However, our structural-compositional studies point to a significant change of the structural configuration of the composites at the nanoscale upon the nitrogen functionalization as the source of the electrodes' capacitance enhancement. The composites fabricated with urea precursor exhibited the highest capacitance, and this fact was associated with the presence of pyridinic N groups that triggered the formation of a high amount of structural defects (vacancies – boundaries) and microporosity, not observed in the samples synthesized with other precursors that mainly contained pyrrolic-graphitic N. [ABSTRACT FROM AUTHOR]

Unprecedented opportunities for early stage cancer detection have recently emerged from the characterization of the personalized protein corona (PC), i.e., the protein cloud that surrounds nanoparticles (NPs) upon exposure to a patients' bodily fluids. Most of these methods require "direct characterization" of the PC., i.e., they necessitate protein isolation, identification, and quantification. Each of these steps can introduce bias and affect reproducibility and inter-laboratory consistency of experimental data. To fulfill this gap, here we develop a nanoparticle-enabled blood (NEB) test based on the indirect characterization of the personalized PC by magnetic levitation (MagLev). The MagLev NEB test works by analyzing the levitation profiles of PC-coated graphene oxide (GO) NPs that migrate along a magnetic field gradient in a paramagnetic medium. For the test validation, we employed human plasma samples from 15 healthy individuals and 30 oncological patients affected by four cancer types, namely breast cancer, prostate cancer, colorectal cancer, and pancreatic ductal adenocarcinoma (PDAC). Over the last 15 years prostate cancer, colorectal cancer, and PDAC have continuously been the second, third, and fourth leading sites of cancer-related deaths in men, while breast cancer, colorectal cancer, and PDAC are the second, third and fourth leading sites for women. This proof-of-concept investigation shows that the sensitivity and specificity of the MagLev NEB test depend on the cancer type, with the global classification accuracy ranging from 70% for prostate cancer to an impressive 93.3% for PDAC. We also discuss how this tool could benefit from several tunable parameters (e.g., the intensity of magnetic field gradient, NP type, exposure conditions, etc.) that can be modulated to optimize the detection of different cancer types with high sensitivity and specificity. [ABSTRACT FROM AUTHOR]

A series of non‐fullerene acceptors based on perylene monoimides coupled in the peri position through phenylene linkers were synthesized via Suzuki‐coupling reactions. Various substitution patterns were investigated using density functional theory (DFT) calculations in combination with experimental data to elucidate the geometry and their optical and electrochemical properties. Further investigations of the bulk properties with grazing incidence wide angle X‐ray scattering (GIWAXS) gave insight into the stacking behavior of the acceptor thin films. Electrochemical and morphological properties correlate with the photovoltaic performance of devices with the polymeric donor PBDB‐T and a maximum efficiency of 3.17 % was reached. The study gives detailed information about structure–property relationships of perylene‐linker‐perylene compounds. [ABSTRACT FROM AUTHOR]

As the demand for energy is rising, the role of batteries and fuel cells in everyday life is undeniable, but fuel cell systems are still currently not employed worldwide mainly because of their cost, which is due to the large amount of Pt used in catalyst layers. Recently, it was demonstrated that catalysts composed by low Pt loading (around 10 μg/cm2) onto ceria (CeO x) matrix are a promising alternative, showing comparable performances with respect to catalysts made by Pt only. Indeed, a strong metal to support interaction between Pt and ceria has been already observed and exploited for application in direct methanol fuel cells. In this context, the aim of the present study is to investigate the stability of innovative Pt-CeO x anode catalyst deposited on two different supports and characterized by means of X-ray Absorption Spectroscopy (XAS). The XANES ex-situ data collected at the Ce L 3 -edge highlighted the stability of ceria when directly deposited onto the nano-Gas Diffusion Layer (nGDL) whereas it is particularly unstable when deposited onto the so-called Carbon Ionomer Layer (CIL), where Ce was found irreversibly reduced to Ce3+ upon contact with the air. These behaviors are confirmed also by preliminary test experiments conducted in operando conditions, using a modified fuel cell designed on purpose. In addition, EXAFS data collected ex-situ at the Pt L 3 -edge evidenced an increase in the fraction of Pt2+ as the overall amount of Pt (or the Pt/Ce ratio) is decreasing, in agreement with existing literature. Our results provide an extended picture about characterization of Pt-CeOx catalyst, focusing on the effects of the hosting support, in order to improve the fabrication of more stable Membrane Electrode Assemblies (MEAs) with low Pt contents to be employed with PEMFCs. The lower efficiency and stability of ptceO 2 anode catalyst sputtered on carbon-lonomer-Layer has been linked to the quick reduction of Ce. [Display omitted] • 2 kind of Pt-ceria anode catalyst were prepared using a novel sputtering technique. • Differences in the efficiency are visible in the first days of operation. • Samples were studied both ex situ and in operando conditions through XAS and SAXS. • When sputtered on Carbon Ionomer Layer, the catalyst is less stable. • Pt2+ fraction increases as the Pt/Ce ratio decreases. [ABSTRACT FROM AUTHOR]

[Display omitted] Formation of high viscous inverse lyotropic liquid crystalline phases in situ upon exposure of low viscous drug-loaded lipid preformulations to synovial fluid provides a promising approach for design of depot formulations for intra-articular drug delivery. Rational formulation design relies on a fundamental understanding of the synovial fluid-mediated dynamic structural transitions occurring at the administration site. At conditions mimicking the in vivo situation, we investigated in real-time such transitions at multiple positions by synchrotron small-angle X-ray scattering (SAXS) combined with an injection-cell. An injectable diclofenac-loaded quaternary preformulation consisting of 72/8/10/10% (w/w) glycerol monooleate/1,2-dioleoyl- glycero -3-phospho-rac-(1-glycerol)/ethanol/water was injected into hyaluronic acid solution or synovial fluid. A fast generation of a coherent drug depot of inverse bicontinuous Im3m and Pn3m cubic phases was observed. Through construction of 2D spatial maps from measurements performed 60 min after injection of the preformulation, it was possible to differentiate liquid crystalline rich- and excess hyaluronic acid solution- or synovial fluid-rich regimes. Synchrotron SAXS findings confirmed that the exposure of the preformulation to the media leads to alterations in structural features in position- and time-dependent manners. Effects of biologically relevant medium composition on the structural features, and implications for development of formulations with sustained drug release properties are highlighted. [ABSTRACT FROM AUTHOR]

Abstract: We describe the hydrothermal synthesis of zeolite SAPO-34 nanoparticles using an amine terminated polymamidoamine dendrimer template. The formation and growth of the zeolite intermediate nanoaggregastes, investigated in situ by small angle X-ray scattering (SAXS), originates porous aggregates with a characteristic fractal structure. A core–shell approach for the analysis of SAXS data allows to correlate the templating action of the dendrimers with the zeolite growth process during the hydrothermal synthesis, and indicates that incorporation of zeolite in the dendrimers surface is the dominant mechanism in the first 3h. The shape transition of the SAXS profile at the late stage of the synthesis has been connected with an aggregation process among primary units that leads to the formation of large clusters. Analysis of the log–log plot of the SAXS spectra during the late stages of synthesis indicates the presence of two linear regions that are connected with the fractal characteristics of the generated aggregates. The formation of large supramolecular assemblies was finally verified by scanning electron microscopy (SEM) analysis which evidenced the presence of large aggregates with visible surface roughness and distributed pores. The main finding of our results puts novel insight in the development of organic–inorganic nanostructured materials based on mesoporous frameworks as well as stimulates the investigation of alternative protocols for the assembly mechanism of novel bio-inspired pourous materials with new characteristics and properties. [Copyright &y& Elsevier]

Cdc45 is an essential protein conserved in all eukaryotes and is involved both in the initiation of DNA replication and the progression of the replication fork. With GINS, Cdc45 is an essential cofactor of the Mcm2-7 replicative helicase complex. Despite its importance, no detailed information is available on either the structure or the biochemistry of the protein. Intriguingly, whereas homologues of both GINS and Mcm proteins have been described in Archaea, no counterpart for Cdc45 is known. Herein we report a bioinformatic analysis that shows a weak but significant relationship among eukaryotic Cdc45 proteins and a large family of phosphoesterases that has been described as the DHH family, including inorganic pyrophosphatases and RecJ ssDNA exonucleases. These enzymes catalyze the hydrolysis of phosphodiester bonds via a mechanism involving two Mn2+ ions. Only a subset of the amino acids that coordinates Mn2+ is conserved in Cdc45. We report biochemical and structural data on the recombinant human Cdc45 protein, consistent with the proposed DHH family affiliation. Like the RecJ exonucleases, the human Cdc45 protein is able to bind singlestranded, but not double-stranded DNA. Small angle x-ray scattering data are consistent with a model compatible with the crystallographic structure of the RecJ/DHH family members. [ABSTRACT FROM AUTHOR]

Investigations of single fragile objects manipulated by optical forces with high brilliance X-ray beams may initiate the development of new research fields such as protein crystallography in an aqueous environment. We have developed a dedicated optical tweezers setup with a compact, portable, and versatile geometry for the customary manipulation of objects for synchrotron radiation applications. Objects of a few micrometers up to a few tens of micrometers size can be trapped for extended periods of time. The selection and positioning of single objects out of a batch of many can be performed semi-automatically by software routines. The performance of the setup has been tested by wide-angle and small-angle X-ray scattering experiments on single optically trapped starch granules, using a synchrotron radiation microbeam. We demonstrate here for the first time the feasibility of microdiffraction on optically trapped protein crystals. Starch granules and insulin crystals were repeatedly raster-scanned at about 50 ms exposure/raster-point up to the complete loss of the structural order. Radiation damage in starch granules results in the appearance of low-angle scattering due to the breakdown of the polysaccharide matrix. For insulin crystals, order along the densely packed [110] direction is preferentially maintained until complete loss of long-range order. [ABSTRACT FROM AUTHOR]

Abstract: Gemcitabine is an anticancer nucleoside analogue active against a wide variety of solid tumors. However it is rapidly deaminated to an inactive metabolite, leading to short biological half-life and induction of resistance. A new prodrug of gemcitabine, coupling squalene to gemcitabine (GemSq), has been designed to overcome the above drawbacks. It has been previously shown that this prodrug displays significantly higher anticancer activity than gemcitabine against leukemia. In the present study the structural modifications of dipalmitoylphosphatidylcholine (DPPC) model membranes induced by increasing concentrations of GemSQ have been investigated using small and wide angle X-ray scattering (SWAXS) and differential scanning calorimetry (DSC). At room temperature an unusual inverse bicontinuous cubic phase formed over a broad composition range. The basic bilayer structure displayed an intermediate order between those of the gel and fluid phases of DPPC. A reversible transition to a fluid lamellar phase occurred upon heating. The transitions between these two phases were governed by different mechanisms depending on the GemSq concentration in the membrane. Finally, the biological relevance of these observations for the cytotoxic activity of GemSq has been discussed. [Copyright &y& Elsevier]

The structure in the symmetrical triblock copolymers PEO-b-PPO-b-PEO and their blend with PEO, studied by small angle x-ray scattering (SAXS), wide angle x-ray scattering (WAXS), and differential scanning calorimetry (DSC), pass from melt to the solid state on cooling. On subsequent heating back to the melt, they pass through disordered and ordered molten states, crystalline structure, and finally back to a disordered melt state. At high temperatures these systems are in the melt in the disordered state approximately described by the mean-field theory. The characteristic lengths of these systems, obtained from SAXS, are proportional to Rg. At lower temperatures, their structure changes to a disordered state which can be described by the concentration fluctuation theory. During cooling, the disordered melt structure changes abruptly into the ordered melt structure. The crystallization destroys this melt structure, forming a new lamellar structure with different periodicity. During heating near the melting point, lamellar periodicity increases very steeply. After melting, the crystalline structure transforms directly to the disordered state. [ABSTRACT FROM AUTHOR]

Background: The potential physiological significance of the nanophase transition of neutral lipids in the core of low density lipoprotein (LDL) particles is dependent on whether the rate is fast enough to integrate small (62uC) temperature changes in the blood circulation. Methodology/Principal Findings: Using sub-second, time-resolved small-angle X-ray scattering technology with synchrotron radiation, we have monitored the dynamics of structural changes within LDL, which were triggered by temperature-jumps and -drops, respectively. Our findings reveal that the melting transition is complete within less than 10 milliseconds. The freezing transition proceeds slowly with a half-time of approximately two seconds. Thus, the time period over which LDL particles reside in cooler regions of the body readily facilitates structural reorientation of the apolar core lipids. Conclusions/Significance: Low density lipoproteins, the biological nanoparticles responsible for the transport of cholesterol in blood, are shown to act as intrinsic nano-thermometers, which can follow the periodic temperature changes during blood circulation. Our results demonstrate that the lipid core in LDL changes from a liquid crystalline to an oily state within fractions of seconds. This may, through the coupling to the protein structure of LDL, have important repercussions on current theories of the role of LDL in the pathogenesis of atherosclerosis. [ABSTRACT FROM AUTHOR]

Abstract: We have studied the influence of four antimicrobial peptides of different secondary and ternary structure – melittin (Mel), protegrin-1 (PG-1), peptidyl-glycylleucine-carboxyamide (PGLa), and gramicidin S (GS) – on the lamellar-to-nonlamellar transition of palmitoyloleoyl phosphatidylethanolamine (POPE) applying differential scanning calorimetry and small-angle X-ray diffraction. None of the peptides studied led to the formation of an inverted hexagonal phase observed for pure POPE at high temperatures. Instead either cubic or lamellar phases were stabilized to different degrees. GS was most effective in inducing a cubic phase, whereas Mel fully stabilized the lamellar phase. The behavior of POPE in the presence of PG-1 and PGLa was intermediate to GS and Mel. In addition to the known role of membrane elasticity we propose two mechanisms, which cause stabilization of the lamellar phase: electrostatic repulsion and lipid/peptide pore formation. Both mechanisms prevent transmembrane contact required to form either an inverted hexagonal phase or fusion pores, as precursors of the cubic phase. [Copyright &y& Elsevier]

Abstract: Mesostructured titania thick films were tested as photovoltaic materials to be used for the fabrication of Grätzel-type dye-sensitized solar cells. The titania films, prepared by evaporation-induced self-assembly, showed a 3D orthorhombic porous mesostructure obtained using non-ionic tri-block copolymers as templating agents and controlled conditions of processing. Thick films (up to 1μm) were synthesized via repetitive dip-coating. Grazing incidence small angle X-ray scattering and X-ray diffraction analysis showed that, after calcination at temperatures higher than 350°C, anatase crystallites were formed in the titania pore walls without loss of organization. The block copolymers were removed after thermal calcination at 350°C, as shown by infrared spectroscopy. Photoaction spectra of 1μm thick films, treated at 350°C, exhibited an incident photon-to-current efficiency above 40% at λ =380nm. [Copyright &y& Elsevier]

Multiblock copolymers with charged blocks are complex systems that show great potential for enhancing the structural control of block copolymers. A pentablock terpolymer PMMA‐b‐PDMAEMA‐b‐P2VP‐b‐PDMAEMA‐b‐PMMA is investigated. It contains two types of midblocks, which are weak cationic polyelectrolytes, namely poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(2‐vinylpyridine) (P2VP). Furthermore, these are end‐capped with short hydrophobic poly(methyl methacrylate) (PMMA) blocks in dilute aqueous solution and thin films. The self‐assembly behavior depends on the degrees of ionization α of the P2VP and PDMAEMA blocks, which are altered in a wide range by varying the pH value. High degrees of ionization of both blocks prevent structure formation, whereas microphase‐separated nanostructures form for a partially charged and uncharged state. While in solutions, the nanostructure formation is governed by the dependence of the P2VP block solubility of the and the flexibility of the PDMAEMA blocks on α, in thin films, the dependence of the segregation strength on α is key. Furthermore, the solution state plays a crucial role in the film formation during spin‐coating. Overall, both the mixing behavior of the 3 types of blocks and the block sequence, governing the bridging behavior, result in strong variations of the nanostructures and their repeat distances. [ABSTRACT FROM AUTHOR]

Individual molecular tilt angle behavior in the smectic C region is represented upon application of a molecular statistical model to the polymorphic terepthal-bis-butylaniline (TBBA) in conjunction with the experimental layer spacings from SAXS measurements using the synchrotron X-ray beam. In the smectic A and smectic H phases of the mesogen, the order parameter fluctuations and pre-transitional effects responsible for sharp changes in the layer spacing and scattered intensities near the phase transition temperature are corroborated with varying positron annihilation lineshapes as a result of electron density fluctuations. [Copyright &y& Elsevier]