This study is devoted to clarifying the crystal structure of diamond particles synthesized by shock wave compression of graphite. Employing a comprehensive suite of methods—including energy dispersive X-ray spectroscopy, XRD, TEM and SEM, laser diffraction, DLS, Raman spectroscopy, nitrogen adsorption-desorption analysis, and SAXS—the research determines the particle size distributions, elucidates the nanocrystalline structure of the diamond particles, and characterizes their impurity compositions. The findings demonstrate that the intrinsic structural differences between diamond produced by detonation of explosives and those obtained through shock wave compression of graphite lead to a significantly lower efficiency of thermal disaggregation for the latter particles. Moreover, inclusions of hexagonal diamond (2H), also known as lonsdaleite, were observed within the crystal structure of the studied particles.

We investigated the effect of two ionic surfactants on the composition and structure of hydrogels obtained by swelling an epoxy amphiphilic polymer network (APN) using a combination of gravimetry and small-angle neutron scattering (SANS). Stoichiometric epoxy APN was synthesized by the reaction of diamino and diepoxy-terminated polypropylene (POP) and polyoxyethylene (POE). Sub- and supercritical solutions of surfactants with either cationic (myristyltrimethylammonium bromide (C14TAB)) or anionic (sodium dodecyl sulfate (SDS)) headgroups in heavy water were used in the preparation of the hydrogels. At supercritical concentrations, SDS exhibited a much stronger effect on the composition and structure of the hydrogels than C14TAB. The details of the hydrogel structure were deduced by general analysis and fitting of the experimental SANS profiles to two model scattering functions exploiting the Percus-Yevick hard-sphere (HS) model and rescaled mean spherical approximation (RMSA), respectively. In the former model, valid for the hydrogels prepared in low concentrated surfactant solutions, spherical domains of average radius of ca. 39-45 & Aring; from a highly swollen network dispersed in a matrix of a poorly swollen network mixed with the bound alkyl surfactant tails were revealed. In the latter model, hydrogels prepared in surfactant solutions of sufficiently high concentrations consist of surfactant micelles dispersed in a matrix of a highly swollen network. The average radii of the C14TAB and SDS micelles formed in the hydrogels were ca. 28 and 17 & Aring;, respectively. The strong binding of surfactant tails with POP chains and dragging of large amounts of highly mobile counterions inside the hydrogels were responsible for the effects observed. This study provides important information about the surfactant organization inside polymer hydrogels, which is important for their applications.

The amyloid-beta peptide (Aβ peptide) is proposed to play a central role in the onset of Alzheimer’s disease (AD). The pathology is associated with the fast accumulation of neurotoxic amyloid aggregates in brain tissues, though the fundamentals of the disease’s progression remain unsolved. It is noted that the preclinical stage of AD may play a crucial role in its further irreversible development. Namely, interactions between lipid membranes and Aβ-peptide molecules incorporated therein at relatively low concentrations should be under a close attention. In this review, we discuss recent works devoted to studying the lipid peptide interactions with a specific focus on the lipid membrane reorganizations caused by Aβ (25–35) peptide in the preclinical AD mimicking conditions. The interactions observed are believed to be important in understanding the mechanisms of the Aβ-peptide destructive effects on lipid membranes and the corresponding onset of the disease. The methods of applied nuclear physics have proven remarkably relevant in such research. The scattering methods provided instrumental information on a level of supramolecular assemblies, while spectrometry allowed obtaining information on the molecular level. Finally, molecular dynamics simulations provided details unachievable by experimental approaches, though the validation role of the latter cannot be undermined. Altogether, the recent advances in research results prove these complementary approaches the most appropriate for tackling the complex issues of biomembrane interactions.

The search for peptides that can specifically bind to regulatory regions in DNA is a necessary step for creating drugs that can regulate gene expression. The work studies the peculiarities of binding of a model peptide, which carries an ionic self-complementary motif and is capable of forming amyloid-like fibrils, with model double-stranded DNA. The stoichiometric ratios of the components of the complex were found using the retardation method in agarose gel. Using microscale thermophoresis, it was shown that the peptide in the oligomeric amyloid-like state is capable of binding to model 45-bp double-stranded DNA, with a micromolar equilibrium dissociation constant. Using electron and atomic force microscopy, the morphology of peptide-DNA complexes was studied; using dynamic light scattering and nanoparticle tracking analysis, as well as small-angle neutron scattering, the spatial parameters of the resulting DNA-peptide complexes were characterized. Molecular dynamics simulations showed that the arginine side chains of the peptide are prone to interact with guanine nitrogenous bases. It was shown that the formation of peptide-dsDNA complexes interferes with the operation of restriction endonucleases that have guanine-cytosine pairs in the recognition center, which is consistent with the results of prediction of interaction sites obtained using computer modeling. The results of the work can be used in the development of peptides capable of interacting with functional regions of DNA, as well as in the development of new carriers for transfection of DNA constructs. ### Competing Interest Statement The authors have declared no competing interest.

We have studied the effect of calcium ions (Ca 2 + ) at various concentrations on the structure of lipid vesicles in the presence of amyloid-beta peptide A beta (25-35). In particular, we have investigated the influence of calcium ions on the formation of recently documented bicelle-like structures (BLSs) emerged as a result of A beta (25-35) triggered membrane disintegration. First, we have shown by using small-angle X-ray and neutron scattering that peptide molecules rigidify the lipid bilayer of gel phase DPPC unilamellar vesicles (ULVs), while addition of the calcium ions to the system hinders this effect of A beta (25-35). Secondly, the A beta (25-35) demonstrates a critical peptide concentration at which the BLSs reorganize from ULVs due to heating and cooling the samples through the lipid main phase transition temperature ( T m ). However, addition of calcium ions does not affect noticeably the A beta- induced formation of BLSs and their structural parameters, though the changes in peptide's secondary structure, e.g. the increased alpha-helix fraction, has been registered by circular dichroism spectroscopy. Finally, according to 31 P nuclear magnetic resonance (NMR) measurements, calcium ions do not affect the lipid-peptide arrangement in BLSs and their ability to align in the magnetic field of NMR spectrometer. The influences of various concentrations of calcium ions on the lipid-peptide interactions may prove biologically important because their local concentrations vary widely in in-vivo conditions. In the present work, calcium ions were investigated as a possible tool aimed at regulating the lipid-peptide interactions that demonstrated the disruptive effect of A beta (25-35) on lipid membranes.

Studies of proteins, found in one of the most stress-resistant animals tardigrade Ramazzottius varieornatus, aim to reveal molecular principles of extreme tolerance to various types of stress and developing applications based on them for medicine, biotechnology, pharmacy, and space research. Tardigrade DNA/RNA-binding damage suppressor protein (Dsup) reduces DNA damage caused by reactive oxygen spices (ROS) produced upon irradiation and oxidative stresses in Dsup-expressing transgenic organisms. This work is focused on the determination of structural features of Dsup protein and Dsup-DNA complex, which refines details of protective mechanism. For the first time, intrinsically disordered nature of Dsup protein with highly flexible structure was experimentally proven and characterized by the combination of small angle X-ray scattering (SAXS) technique, circular dichroism spectroscopy, and computational methods. Low resolution models of Dsup protein and an ensemble of conformations were presented. In addition, we have shown that Dsup forms fuzzy complex with DNA.

Small-angle X-ray scattering is applied to study particle correlations in concentrated (up to 7.5 vol% magnetite) aqueous magnetic fluids with double-layer coating by either oleic or lauric acids. The structure of aggregates in these fluids is analyzed when diluting samples with the goal of finding out a concentration threshold at which the aggregates can be considered weakly interacting independent formations. For dilute systems, suitable models fitting experimental scattering curves are proposed, which take into account the polydispersity of both particles and aggregates. It is shown that particle correlations found in aggregates are dependent on the surfactant coating.

Results of experiments on small-angle scattering of neutrons and X-rays on colloidal suspensions with anisometric barium hexaferrite nanoparticles in an aqueous solvent are reported. It has been shown that the preparation according to a new method produces fairly stable colloids with two types of particles of reproducible morphology and size: large lamellar-shaped particles ( 100 nm) with a thickness of 7 nm and small isometric particles with a size of 6 nm.

Our complementary experimental data and molecular dynamics (MD) simulations results reveal the structure of previously observed lipid bicelle-like structures (BLSs) formed in the presence of amyloid-beta peptide Aβ(25-35) below the main phase transition temperature (Tm) of saturated phosphatidylcholine lipids and small unilamellar vesicles (SUVs) above this temperature. First, we show by using solid-state 31P nuclear magnetic resonance (NMR) spectroscopy that our BLSs being in the lipid gel phase demonstrate magnetic alignment along the magnetic field of NMR spectrometer and undergo a transition to SUVs in the lipid fluid phase when heated through the Tm. Secondly, thanks to the BLS alignment we present their lipid structure. Lipids are found located not only in the flat bilayered part but also around its perimeter, which is corroborated by the results of coarse-grained (CG) MD simulations. Finally, peptides appear to mix randomly with lipids in SUVs while assuming predominantly unordered secondary structures revealed by circular dichroism (CD), Raman spectroscopy, and all-atom MD simulations. Importantly, the former is changing little when the system undergoes morphological transitions between BLSs and SUVs. Our structural results then offer a platform for studying and understanding mechanisms of morphological transformations caused by the disruptive effect of amyloid-beta peptides on the lipid bilayer.

An effect of receptor-binding domain (RBD) of SARS-CoV-2 S-protein on structural parameters of model lipid membranes presented by dimyristoylphosphatidylcholine (DMPC) systems with cholesterol and melatonin impurities is studied by small angle neutron scattering (SANS). It is shown that an increase in melatonin concentration in the lipid membrane leads to a decrease in the thickness of the lipid bilayer, while an increase in the concentration of cholesterol leads to an increase in its thickness. It is suggested that increasing the concentration of melatonin in a membrane prevents the interaction of coronaviral S-protein with a lipid membrane of a cell. In the presence of cholesterol in the system, the interaction of a lipid membrane with an active part of S-protein occurs depending on a phase state of the lipid: in the case of a gel phase, there is no changes in structural parameters, but at higher temperatures in the case of a liquid crystal phase, an addition of RBD SARS-CoV-2 to the system causes a reduce in the membrane thickness.

Magnetodielectric materials are highly interesting inthe scopeof Internet of Things (IoT)-related devices such as antennas, sensors,and actuators, as they allow the magnetic control of the dielectricresponse. Among the different possible methods for their development,the combination of photocurable polymers and magnetic nanoparticlesallows more sustainable processes with high production velocities,room processing temperature, and the capability to fabricate a largevariety of specific shapes with high resolution. In this context,photocurable magnetic hybrid materials based on polyurethane acrylate(PUA) and on different magnetic micro- and nanoparticles, includingcobalt ferrite oxide (CFO), magnetite (Fe3O4), and a neodymium iron boron alloy (NdFeB), have been developed.The influence of filler type and content on the photopolymerizationprocess, sample morphology, physicochemical properties, electricalconductivity, and magnetic properties has been investigated. Fillerdispersion has also been studied by neutron scattering techniques,enabling the determination of the organization of the filler aggregates,which plays an essential role in the overall characteristics of thecomposites. Materials with maximum magnetodielectric coefficients(MD %) as large as 28% have been obtained for the sample with 6% NdFeBfiller content, making these magnetic composites of paramount interestfor the fabrication of magnetodielectric devices in the context ofthe digital transition.

Ribosome biogenesis is an energy-intense multistep process where even minimal defects can cause severe phenotypes up to cell death. Ribosome assembly is facilitated by biogenesis factors such as ribosome assembly factors. These proteins facilitate the interaction of ribosomal proteins with rRNA and correct rRNA folding. One of these maturation factors is RimP which is required for efficient 16S rRNA processing and 30S ribosomal subunit assembly. Here, we describe the binding mode of Staphylococcus aureus RimP to the small ribosomal subunit and present a 4.2 Å resolution cryo-EM reconstruction of the 30S-RimP complex. Together with the solution structure of RimP solved by NMR spectroscopy and RimP-uS12 complex analysis by EPR, DEER, and SAXS approaches, we show the specificity of RimP binding to the 30S subunit from S. aureus. We believe the results presented in this work will contribute to the understanding of the RimP role in the ribosome assembly mechanism.

In this study, we aimed to design and research proton-conducting membranes based on Aquivion®-type material that had been modified with detonation nanodiamonds (particle size 4–5 nm, 0.25–5.0 wt. %). These nanodiamonds carried different functional groups (H, OH, COOH, F) that provided the hydrophilicity of the diamond surface with positive or negative potential, or that strengthened the hydrophobicity of the diamonds. These variations in diamond properties allowed us to find ways to improve the composite structure so as to achieve better ion conductivity. For this purpose, we prepared three series of membrane films by first casting solutions of perfluorinated Aquivion®-type copolymers with short side chains mixed with diamonds dispersed on solid substrates. Then, we removed the solvent and the membranes were structurally stabilized during thermal treatment and transformed into their final form with –SO3H ionic groups. We found that the diamonds with a hydrogen-saturated surface, with a positive charge in aqueous media, contributed to the increase in proton conductivity of membranes to a greater rate. Meanwhile, a more developed conducting diamond-copolymer interface was formed due to electrostatic attraction to the sulfonic acid groups of the copolymer than in the case of diamonds grafted with negatively charged carboxyls, similar to sulfonic groups of the copolymer. The modification of membranes with fluorinated diamonds led to a 5-fold decrease in the conductivity of the composite, even when only a fraction of diamonds of 1 wt. % were used, which was explained by the disruption in the connectivity of ion channels during the interaction of such diamonds mainly with fluorocarbon chains of the copolymer. We discussed the specifics of the mechanism of conductivity in composites with various diamonds in connection with structural data obtained in neutron scattering experiments on dry membranes, as well as ideas about the formation of cylindrical micelles with central ion channels and shells composed of hydrophobic copolymer chains. Finally, the characteristics of the network of ion channels in the composites were found depending on the type and amount of introduced diamonds, and correlations between the structure and conductivity of the membranes were established.

Pancake bonding phenomenology is applied for the first time in a bioorganic system, the pigment eumelanin, via a hydration-induced decrease of the interplanar distance down to 3.19 Å. The observation explains the long-term inconsistency between electron paramagnetic resonance and muon spin relaxation data for eumelanin.

In addition to exhibited antioxidant and anti-inflammatory activity, fullerene C60 is a promising wound healing agent. An important stage in the production of fullerene-based ointments is the stability of the aqueous fullerene dispersion (AFD) with minimum size of colloidal fullerene aggregates and sufficiently high concentration. To achieve these parameters tangential flow filtration of fullerene C60 was used ("green technology"). As estimated by small-angle neutron scattering and dynamic light scattering purified AFDs with narrow-size distribution nanoclusters have a size of 6 nm and are assembled into agglomerates which reach a size of 150 nm. The ability of the AFD to exhibit regenerative activity was studied using the animal wound model. This study shows for the first time that the fullerene-based composition stimulates the healing of wounds of various origins. We assume that the mechanism of the AFD wound-healing activity is associated with the aryl hydrocarbon receptor and macrophages activity.

We have studied by means of small angle neutron scattering and diffraction, and molecular dynamics simulations the effect of lipid membrane fluidity on the amyloid-beta peptide interactions with the membrane. These interactions have been discovered previously to trigger the reorganization of model membranes between unilamellar vesicles and planar membranes (bicelle-like structures) during the lipid phase transition. The morphology changes were taking place in rigid membranes prepared of fully saturated lipids and were proposed to play a role in the onset of amyloid related disorders. We show in this study that the replacement of fully saturated lipids by more fluid mono-unsaturated lipids eliminates the mentioned morphology changes, most likely due to the absence of phase transition within the temperature range investigated. We have therefore controlled the membrane rigidity also while ensuring the presence of membrane phase transition within the biologically relevant temperatures. It was done by the addition of melatonin and/or cholesterol to the initial membranes made of saturated lipids. Small angle neutron scattering experiments performed over a range of cholesterol and melatonin concentrations show their distinctive effects on the local membrane structure only. The cholesterol for example affects the membrane curvature such that spontaneously formed unilamellar vesicles are of much larger sizes than those formed by the neat lipid membranes or membranes with melatonin added. The temperature dependent experiments, however, reveal no influence on the previously discovered membrane breakage whether cholesterol or melatonin have been added.

The small-angle neutron-scattering spectra of polydisperse populations of unilamellar vesicles are analyzed as functions of the concentration of maltose in a heavy-water solution. The spectra are recorded using a YuMO small-angle spectrometer at the Dzhelepov Laboratory of Neutron Physics, Joint Institute for Nuclear Research (Dubna, Russia). Two types of nanosystems developed at the Orekhovich Institute of Biomedical Chemistry are studied. These are a phospholipid-transport nanosystem and the Indolip nanodrug based on a phospholipid-transport nanosystem. The possibilities of obtaining data on the vesicular structure of nanodrugs based on a phospholipid-transport nanosystem from small-angle neutron scattering data are discussed. The computer analysis of small-angle scattering spectra is based on application of the method of separated form factors. The obtained values of the basic structural parameters of these vesicular systems (the average radius of vesicles in the population, the thickness of the bilayer across the membrane, the polydispersity coefficient, etc.) are generally consistent with the corresponding results of the similar processing of small-angle X-ray scattering data. However, the method of small-angle neutron scattering in comparison with small-angle X-ray scattering turns out to be less sensitive to the detailed analysis of structural features of the bilayer of the vesicle shell.

We report on the effect of a hydrocarbon (n-dodecane) on the rheological properties and shapes of the hybrid wormlike micelles (WLMs) of a surfactant potassium oleate with an embedded polymer poly(4-vinylpyridine). With and without hydrocarbon solutions, the hybrid micelles exhibit the same values of viscosity at shear rates typical for hydraulic fracturing (HF) tests, as solutions of polymer-free WLMs. Therefore, similar to WLMs of surfactants, they could be applied as thickeners in HF fluids without breakers. At the same time, in the presence of n-dodecane, the hybrid micelles have much higher drag-reducing efficiency compared to microemulsions formed in polymer-free systems since they form “beads-on-string” structures according to results obtained using cryo-transmission electron microscopy (cryo-TEM), dynamic-light scattering (DLS), and small-angle X-ray scattering (SAXS). Consequently, they could also act as drag-reducing agents in the pipeline transport of recovered oil. Such a unique multi-functional additive to a fracturing fluid, which permits its concurrent use in oil production and oil transportation, has not been proposed before.

Recently, the fabrication of ferrite nanoparticles in controlled varied shape and ferrofluids obtained with their help has become another requirement of interest for researchers. The present article reports the structural features of a new ferrofluid containing large, rod-like CuFe 2 O 4 particles stabilized by a double layer of triple surfactant. Depending on the experimental method used, i.e., neutrons or X-rays, and, accordingly, the properties of the solvent (H 2 O, D 2 O), several peculiarities of the system, such as the morphology and particle dimensions, and the sizes of the surfactant coatings have been obtained.

Amyloid-β peptide interactions with model lipid membranes have been studied by means of small angle neutron scattering and molecular dynamics simulations. These interactions had been indicated recently as an origin of the membrane structure reorganizations between spherical small unilamellar vesicles and planar bicelle-like structures. In present work, we investigate the influence of charge on the peptide-triggered morphological changes by introducing the anionic lipid DMPS to the underlying DMPC membrane. Changes to the membrane thickness and the overall membrane structure with and without Aβ25-35 incorporated have been investigated over a wide range of temperatures. Our results document the previously reported morphological reformations between bicelle-like structures present in gel phase and small unilamellar vesicles present in fluid phase to be independent from the charge existence in the system.