Non-canonical self-assembly of surfactant/cosurfactant mixtures detected by combining the power of SANS and cryo-TEM.

Hypothesis: Addition of cosurfactants to surfactant micelles is normally assumed to lead, via a continuous change of the packing parameter, to a transition of spherical micelles to elongated ones, then to wormlike viscoelastic micelles and finally, via a phase transition, to planar lamellae. However, this conventional structural sequence may be different, if surfactants with variable head group size and cosurfactants that favour strongly planar structures are employed.

Experiments: A phase study was done on solutions of the nonionic surfactant Tween-20 (Tw20) with increasing amounts of added cosurfactant 2-ethylhexyl glycerine (EHG).

Cryo-SEM in haematological research.

Cryogenic scanning electron microscopy (cryo-SEM) is a powerful imaging technique used in cellular biology, providing high-resolution micrographs that show the complexity and dynamics of biological systems. The use of high-pressure freezing (HPF) for specimen fixation preserves cellular structures in their native, hydrated state, avoiding the artefacts introduced by conventional chemical fixation, while modern microscopes provide high-resolution imaging at low electron acceleration voltage, giving fine structural details. That makes cryo-SEM a unique tool for understanding cellular complexity.

Lyotropic Liquid Crystalline Phase Behavior of Boron Nitride Nanotube Aqueous Dispersions.

Boron nitride nanotubes (BNNTs) are gaining significant interest due to their outstanding mechanical and thermal properties, as well as their potential to serve as a model nanorod system. Processing BNNT liquid crystalline (LC) dispersions enables precise control over BNNT orientation in macroscopic assemblies, while their low absorption in the visible spectrum facilitates studying LCs at exceptionally high concentrations. Here, we investigate the behavior of BNNTs in aqueous solutions stabilized by the surfactant sodium deoxycholate (SDC), examining the effect of BNNT purity and BNNT-SDC concentrations on lyotropic LC formation.

Supramolecular self-assembly of metal complex surfactants (MeCS) into micellar nanoscale reactors in aqueous solution.

Surfactants are amphiphilic molecules that can form micellar structures with a hydrophobic core and a hydrophilic corona in water. In this work, we combine the remarkable properties of photoactive metal complexes with the supramolecular organization of surfactants to create photoactive vessels that support photocatalytic processes in aqueous media, even for starting materials that are insoluble in water. Herein, we report a library of photoactive metal complex surfactants (MeCSs) and their photophysical and photochemical properties.

Ion effects on co-existing pseudo-phases in aqueous surfactant solutions: cryo-TEM, rheometry, and quantification.

Hypothesis: Specific alkaline cation effects control the area per headgroup of alkylester sulphates, which modifies the spontaneous packing of the surfactants. The resulting effective packing minimizes the total bending energy frustration and results in a Boltzmann distribution of coexisting pseudo-phases. These pseudo-phases constitute of micelles and other structures of complex morphology: cylindrical sections, end-caps, branching points, and bilayers, all in dynamic equilibrium.

Tadpole-Like Anisotropic Polymer/Lipid Janus Nanoparticles for Nose-to-Brain Drug Delivery: Importance of Geometry, Elasticity on Mucus-Penetration Ability.

Asymmetric geometry (aspect ratio >1), moderate stiffness (i.e., semielasticity), large surface area, and low mucoadhesion of nanoparticles are the main features to reach the brain by penetrating across the nasal mucosa.

Selective labeling of phosphatidylserine for cryo-TEM by a two-step immunogold method.

Immunogold labeling in transmission electron microscopy (TEM) utilizes the high electron density of gold nanoparticles conjugated to proteins to identify specific antigens in biological samples. In this work we applied the concept of immunogold labeling for the labeling of negatively charged phospholipids, namely phosphatidylserine, by a simple protocol, performed entirely in the liquid-phase, from which cryo-TEM specimens can be directly prepared. Labeling included a two-step process using biotinylated annexin-V and gold-conjugated streptavidin.

Extracellular vesicles of the Gram-positive gut symbiont Bifidobacterium longum induce immune-modulatory, anti-inflammatory effects.

The gut microbiota is now well known to affect the host's immune system. One way of bacterial communication with host cells is via the secretion of vesicles, small membrane structures containing various cargo. Research on vesicles secreted by Gram-positive gut bacteria, their mechanisms of interaction with the host and their immune-modulatory effects are still relatively scarce.

Glycan Node Analysis Detects Varying Glycosaminoglycan Levels in Melanoma-Derived Extracellular Vesicles.

Extracellular vesicles (EVs) play important roles in (patho)physiological processes by mediating cell communication. Although EVs contain glycans and glycosaminoglycans (GAGs), these biomolecules have been overlooked due to technical challenges in comprehensive glycome analysis coupled with EV isolation. Conventional mass spectrometry (MS)-based methods are restricted to the assessment of N-linked glycans.

The nanostructure of polyelectrolyte complexes of QPDMAEMA--POEGMA copolymers and oppositely charged polyelectrolytes, and their stability in the presence of serum albumin.

Quaternized poly(2-(dimethylamino) ethyl methacrylate)--poly(oligo(ethyleneglycol) methyl ether methacrylate) (QPDMAEMA--POEGMA) is a copolymer of a positively charged block and a non-ionic hydrophilic block. The positively charged block, QPDMAEMA, electrostatically interacts with oppositely charged polymers, , poly(acrylic acid) (PAA) and DNA, to form a complex. This complex is stable in aqueous solution due to the hydrophilic block, POEGMA, which provides colloidal stability and biocompatibility.

Complexes of Charged-Neutral Block Copolymers and Surfactants: Process-Dependent Features and Long-Term Stability of Their Aqueous Dispersions.

Aqueous dispersions of charged-neutral block copolymers (poly(acrylamide)--poly(acrylate)) complexed with an oppositely charged surfactant (dodecyltrimethylammonium) have been prepared by different approaches: the simple mixing of two solutions (MS approach) containing the block copolymer and surfactant, with their respective simple counterions, and dispersion of a freeze-dried complex salt prepared in the absence of simple counterions (CS approach). The CS particles were investigated under different conditions: dispersion of a CS in salt-free water and dispersion of a CS in a dilute salt solution, the latter condition yielding dispersions with the same composition as the MS process. Additionally, aged dispersions (up to 6 months) and dispersed complexes of the polyacrylate homopolymer and dodecyltrimethylammonium surfactant were evaluated.

The effect of specimen preparation on the nanostructure of SLES aqueous solutions observed by cryo-TEM.

Sodium lauryl ether sulphate (SLES) is a detergent widely used in cosmetics and personal-care industries; hence, it is of particular interest to study the self-assembled nanostructure it forms at different conditions. Cryogenic transmission electron microscopy (cryo-TEM) is the most suitable technique for the direct-imaging of such systems. However, since SLES is sensitive to flow and shear, specimen preparation artefacts may misrepresent the native state of the solution.

Self-Aggregation in Aqueous Media of Amphiphilic Diblock and Random Block Copolymers Composed of Monomers with Long Side Chains.

Amphiphilic diblock copolymers and hydrophobically modified random block copolymers can self-assemble into different structures in a selective solvent. The formed structures depend on the copolymer properties, such as the ratio between the hydrophilic and the hydrophobic segments and their nature. In this work, we characterize by cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) the amphiphilic copolymers poly(2-dimethylamino ethyl methacrylate)--poly(lauryl methacrylate) (PDMAEMA--PLMA) and their quaternized derivatives QPDMAEMA--PLMA at different ratios between the hydrophilic and the hydrophobic segments.

Unraveling multilayered extracellular vesicles: Speculation on cause.

Extracellular vesicles (EVs) are cell-released, heterogenous nanoparticles that play important roles in (patho)physiological processes through intercellular communication. EVs are often depicted as having a single lipid bilayer, but many studies have demonstrated the existence of multilayered EVs. There has been minimal inquiry into differences between unilamellar and multilamellar EVs in terms of biogenesis mechanisms and functional effects.

Sucrose-based cryoprotective storage of extracellular vesicles.

Advancements in extracellular vesicle (EV) studies necessitate the development of optimized storage conditions to ensure preservation of physical and biochemical characteristics. In this study, the most common buffer for EV storage (phosphate-buffered saline/PBS) was compared to a cryoprotective 5% sucrose solution. The size distribution and concentration of EVs from two different sources changed to a greater extent after -80 °C storage in PBS compared to the sucrose solution.

Liquid crystals of neat boron nitride nanotubes and their assembly into ordered macroscopic materials.

Boron nitride nanotubes (BNNTs) have attracted attention for their predicted extraordinary properties; yet, challenges in synthesis and processing have stifled progress on macroscopic materials. Recent advances have led to the production of highly pure BNNTs. Here we report that neat BNNTs dissolve in chlorosulfonic acid (CSA) and form birefringent liquid crystal domains at concentrations above 170 ppmw.

Versatile acid solvents for pristine carbon nanotube assembly.

Chlorosulfonic acid and oleum are ideal solvents for enabling the transformation of disordered carbon nanotubes (CNTs) into precise and highly functional morphologies. Currently, processing these solvents using extrusion techniques presents complications due to chemical compatibility, which constrain equipment and substrate material options. Here, we present a novel acid solvent system based on methanesulfonic or -toluenesulfonic acids with low corrosivity, which form true solutions of CNTs at concentrations as high as 10 g/liter (≈0.

Considerations for extracellular vesicle and lipoprotein interactions in cell culture assays.

With an exponential increase in extracellular vesicle (EV) studies in the past decade, focus has been placed on standardization of experimental design to ensure inter-study comparisons and validity of conclusions. In the case of in vitro assays, the composition of cell culture media is important to consider for EV studies. In particular, levels of lipoproteins, which are critical components of the interstitial fluid, should be taken into consideration.

Extracellular vesicle glucose transporter-1 and glycan features in monocyte-endothelial inflammatory interactions.

Monocyte-induced endothelial cell inflammation is associated with multiple pathological conditions, and extracellular vesicles (EVs) are essential nanosized components of intercellular communication. EVs derived from endotoxin-stimulated monocytes were previously shown to carry pro-inflammatory proteins and RNAs. The role of glucose transporter-1 (GLUT-1) and glycan features in monocyte-derived EV-induced endothelial cell inflammation remains largely unexplored.

Effects of Adipose-Derived Biogenic Nanoparticle-Associated microRNA-451a on Toll-like Receptor 4-Induced Cytokines.

Extracellular vesicles (EVs) are cell-released nanoparticles that transfer biomolecular content between cells. Among EV-associated biomolecules, microRNAs (miRNAs/miRs) represent one of the most important modulators of signaling pathways in recipient cells. Previous studies have shown that EVs from adipose-derived mesenchymal stromal cells (MSCs) and adipose tissue modulate inflammatory pathways in macrophages.

Cryogenic Electron Microscopy Methodologies as Analytical Tools for the Study of Self-Assembled Pharmaceutics.

Many pharmaceutics are aqueous dispersions of small or large molecules, often self-assembled in complexes from a few to hundreds of molecules. In many cases, the dispersing liquid is non-aqueous. Many pharmaceutical preparations are very viscous.

Using Microemulsions: Formulation Based on Knowledge of Their Mesostructure.

Microemulsions, as thermodynamically stable mixtures of oil, water, and surfactant, are known and have been studied for more than 70 years. However, even today there are still quite a number of unclear aspects, and more recent research work has modified and extended our picture. This review gives a short overview of how the understanding of microemulsions has developed, the current view on their properties and structural features, and in particular, how they are related to applications.

Extending Cryo-EM to Nonaqueous Liquid Systems.

Cryogenic-temperature transmission electron microscopy (cryo-TEM) of aqueous systems has become a widely used methodology, especially in the study of biological systems and synthetic aqueous systems, such as amphiphile and polymer solutions. Cryogenic-temperature scanning electron microscopy (cryo-SEM), while not as widely used as cryo-TEM, is also found in many laboratories of basic and applied research. The application of these methodologies, referred to collectively as cryogenic-temperature electron microscopy (cryo-EM) for direct nanostructural studies of nonaqueous liquid systems is much more limited, although such systems are important in basic research and are found in a very large spectrum of commercial applications.

Enhanced ordering in length-polydisperse carbon nanotube solutions at high concentrations as revealed by small angle X-ray scattering.

Carbon nanotubes (CNTs) are stiff, all-carbon macromolecules with diameters as small as one nanometer and few microns long. Solutions of CNTs in chlorosulfonic acid (CSA) follow the phase behavior of rigid rod polymers interacting via a repulsive potential and display a liquid crystalline phase at sufficiently high concentration. Here, we show that small-angle X-ray scattering and polarized light microscopy data can be combined to characterize quantitatively the morphology of liquid crystalline phases formed in CNT solutions at concentrations from 3 to 6.