Structural Characteristics and Properties of the RNA-Binding Protein hnRNPK at Multiple Physical States.

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an RNA-binding protein containing low-complexity domains (LCDs), which are known to regulate protein behavior under stress conditions. This study demonstrates the ability to control hnRNPK's transitions into four distinct material states-monomer, soluble aggregate, liquid droplet, and fibrillar hydrogel-by modulating environmental factors such as temperature and protein concentration. Importantly, the phase-separated and hydrogel states are newly identified for eGFP-hnRNPK, marking a significant advancement in understanding its material properties.

Tuning the nanostructure and tribological properties of a non-ionic deep eutectic solvent with water addition.

Hypothesis: The addition of water to a non-ionic N-oxide deep eutectic solvent(DES) composed of phenylacetic acid (PhAA) and N-dodecylmorpholine-N-oxide(MO-12) in a 1:1 M ratio(PhAA/MO-12) will promote interfacial nanostructure formation due to increased proton transfer and solvophobic interactions, leading to reduced friction.

Experiments: The interfacial structure and friction of PhAA/MO-12 with water content up to 41.9 wt% were investigated at mica surfaces.

Long-Range Surface Forces in Salt-in-Ionic Liquids.

Ionic liquids (ILs) are a promising class of electrolytes with a unique combination of properties, such as extremely low vapor pressures and nonflammability. Doping ILs with alkali metal salts creates an electrolyte that is of interest for battery technology. These salt-in-ionic liquids (SiILs) are a class of superconcentrated, strongly correlated, and asymmetric electrolytes.

Concluding remarks: Dense ionic fluids: because sometimes, more is more.

It is a formidable challenge, and a distinct privilege, to provide the concluding remarks for this on Dense Ionic Fluids (DIFs). What follows is an inherently subjective distillation of the insights that have shaped our understanding of these complex systems over the last few days, with the goal of capturing the essence of the Discussion and providing suggestions for future investigations in this rapidly evolving field. DIFs are a fascinating class of electrolyte systems characterized by high ion concentrations in correlated domains.

Nanostructure and Dynamics of the Locally Concentrated Ionic Liquid 2:1 (wt:wt) HMIM FAP:TFTFE and HMIM FAP on Graphite and Gold Electrodes as a Function of Potential.

Video-rate atomic force microscopy (AFM) is used to record the near-surface nanostructure and dynamics of one pure ionic liquid (IL), 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate (HMIM FAP), and a locally-concentrated IL comprising HMIM FAP with the low viscosity diluent 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFTFE), on highly oriented pyrolytic graphite (HOPG) and Au(111) electrodes as a function of potential. Over the potential range measured (open-circuit potential ± 1 V), different near-surface nanostructures are observed. For pure HMIM FAP, globular aggregates align in rows on HOPG, whereas elongated and worm-like nanostructures form on Au(111).

Bulk Nanostructure of Mixtures of Choline Arginate, Choline Lysinate, and Water.

Neutron diffraction with empirical potential structure refinement was used to investigate the bulk liquid nanostructure of mixtures of choline arginate (Ch[Arg]), choline lysinate (Ch[Lys]), and water at mole ratios of 1Ch[Arg]:1Ch[Lys]:6HO (balanced), 1Ch[Arg]:1Ch[Lys]:20HO (balanced dilute), 3Ch[Arg]:1Ch[Lys]:12HO (Arg rich), and 1Ch[Arg]:3Ch[Lys]:12HO (Lys rich). The Arg and Lys anions tend not to associate due to electrostatic repulsion between charge groups and weak anion-anion attractions. This means that the local ion structures around the anions in these mixtures resemble the parent single-component systems.

Nanostructure and Dynamics of Aprotic Ionic Liquids at Graphite Electrodes as a Function of Potential.

Atomic force microscope (AFM) videos reveal the near-surface nanostructure and dynamics of the ionic liquids (ILs) 1-butyl-3-methylimidazolium dicyanamide (BMIM DCA) and 1-hexyl-3-methylimidazolium dicyanamide (HMIM DCA) above highly oriented pyrolytic graphite (HOPG) electrodes as a function of surface potential. Molecular dynamics (MD) simulations reveal the molecular-level composition of the nanostructures. In combination, AFM and MD show that the near-surface aggregates form via solvophobic association of the cation alkyl chains at the electrode interface.

Ions Adsorbed at Amorphous Solid/Solution Interfaces Form Wigner Crystal-like Structures.

When a surface is immersed in a solution, it usually acquires a charge, which attracts counterions and repels co-ions to form an electrical double layer. The ions directly adsorbed to the surface are referred to as the Stern layer. The structure of the Stern layer normal to the interface was described decades ago, but the lateral organization within the Stern layer has received scant attention.

H-bond network, interfacial tension and chain melting temperature govern phospholipid self-assembly in ionic liquids.

Hypothesis: The self-assembly structures and phase behaviour of phospholipids in protic ionic liquids (ILs) depend on intermolecular forces that can be controlled through changes in the size, polarity, and H-bond capacity of the solvent.

Experiments: The structure and temperature stability of the self-assembled phases formed by four phospholipids in three ILs was determined by a combination of small- and wide-angle X-ray scattering (SAXS and WAXS) and small-angle neutron scattering (SANS). The phospholipids have identical phosphocholine head groups but different alkyl tail lengths and saturations (DOPC, POPC, DPPC and DSPC), while the ILs' amphiphilicity, H-bond network density and polarity are varied between propylammonium nitrate (PAN) to ethylammonium nitrate (EAN) to ethanolammonium nitrate (EtAN).

Bulk nanostructure of a deep eutectic solvent with an amphiphilic hydrogen bond donor.

Neutron diffraction with empirical potential structure refinement (EPSR) show the deep eutectic solvent (DES) 1 : 4 choline chloride : butyric acid is amphiphilically nanostructured. Nanostructure results from solvophobic interactions between the alkyl chains of the butyric acid hydrogen bond donor (HBD) and is retained with addition of 10 wt% water. EPSR fits to the diffraction data is used to produce a three-dimensional model of the liquid which is interrogated to reveal the interactions leading to the solvophobic effect, and therefore nanostructure, in this DES at atomic resolution.

Nanostructure of Locally Concentrated Ionic Liquids in the Bulk and at Graphite and Gold Electrodes.

The physical properties of ionic liquids (ILs) have led to intense research interest, but for many applications, high viscosity is problematic. Mixing the IL with a diluent that lowers viscosity offers a solution if the favorable IL physical properties are not compromised. Here we show that mixing an IL or IL electrolyte (ILE, an IL with dissolved metal ions) with a nonsolvating fluorous diluent produces a low viscosity mixture in which the local ion arrangements, and therefore key physical properties, are retained or enhanced.

Effect of Potential on the Nanostructure Dynamics of Ethylammonium Nitrate at a Graphite Electrode.

Video-rate atomic force microscopy (AFM) is used to study the near-surface nanostructure dynamics of the ionic liquid ethylammonium nitrate (EAN) at a highly oriented pyrolytic graphite (HOPG) electrode as a function of potential in real-time for the first time. The effects of varying the surface potential and adding 10 wt% water on the nanostructure diffusion coefficient are probed. For both EAN and the 90 wt% EAN-water mixture, disk-like features ≈9 nm in diameter and 1 nm in height form above the Stern layer at all potentials.

Phase behaviour and aggregate structures of the surface-active ionic liquid [BMIm][AOT] in water.

Hypothesis: The surface-active ionic liquid, 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate ([BMIm][AOT]), has a sponge-like bulk nanostructure consisting of percolating polar and apolar domains formed by the ion charge groups and alkyl chains, respectively. We hypothesise that added water will swell the polar domains and change the liquid nanostructure.

Experiments: Small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and polarizing optical microscopy (POM) were used to investigate the nanostructure of [BMIm][AOT] as a function of water content.

Unusual phosphatidylcholine lipid phase behavior in the ionic liquid ethylammonium nitrate.

Hypothesis: The forces that govern lipid self-assembly ionic liquids are similar to water, but their different balance can result in unexpected behaviour.

Experiments: The self-assembly behaviour and phase equilibria of two phospholipids, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), in the most common protic ionic liquid, ethylammonium nitrate (EAN) have been investigated as function of composition and temperature by small- and wide-angle X-ray scattering (SAXS/WAXS) and small-angle neutron scattering (SANS).

Findings: Both lipids form unusual self-assembly structures and show complex and unexpected phase behaviour unlike that seen in water; DSPC undergoes a gel L to crystalline L phase transition on warming, while POPC forms worm-like micelles L upon dilution.

Mixing Ionic Liquids Affects the Kinetics and Thermodynamics of the Oxygen/Superoxide Redox Couple in the Context of Oxygen Sensing.

The electrochemical oxygen reduction reaction is vital for applications such as fuel cells, metal air batteries and for oxygen gas sensing. Oxygen undergoes a 1-electron reduction process in dry ionic liquids (ILs) to form the electrogenerated superoxide ion that is solvated and stabilized by IL cations. In this work, the oxygen/superoxide (O/O ) redox couple has been used to understand the effect of mixing ILs with different cations in the context of developing designer electrolytes for oxygen sensing, by employing cyclic voltammetry at both gold and platinum electrodes.

Effect of ion structure on the physicochemical properties and gas absorption of surface active ionic liquids.

Surface active ionic liquids (SAILs) combine useful characteristics of both ionic liquids (ILs) and surfactants, hence are promising candidates for a wide range of applications. However, the effect of SAIL ionic structures on their physicochemical properties remains unclear, which limits their uptake. To address this knowledge gap, in this work we investigated the density, viscosity, surface tension, and corresponding critical micelle concentration in water, as well as gas absorption of SAILs with a variety of cation and anion structures.

How Does Nanostructure in Ionic Liquids and Hybrid Solvents Affect Surfactant Self-Assembly?

Ionic liquids (ILs) have recently emerged as novel classes of solvents that support surfactant self-assembly into micelles, liquid crystals, and microemulsions. Their low volatility and wide liquid stability ranges make them attractive for many diverse applications, especially in extreme environments. However, the number of possible ion combinations makes systematic investigations both challenging and rare; this is further amplified when mixtures are considered, whether with water or other H-bonding components such as those found in deep eutectics.

A mucus-inspired solvent-free carbon dot-based nanofluid triggers significant tribological synergy for sulfonated h-BN reinforced epoxy composites.

Nano-filler reinforced polymer-based composites have attracted extensive attention in tribology; however, to date, it is still challenging to construct a favorable lubricating system with excellent compatibility, lubricity and durability using nano-filler reinforced polymer-based composites. Herein, sulfonated boron nitride nano-sheets (h-BN@PSDA) are prepared and used as nano-fillers for epoxy resins (EPs), to improve friction and wear along with thermal conductivity. Furthermore, inspired by the lubricating principle and structure of snail mucus, a solvent-free carbon dot-based nanofluid (F-CDs) is fabricated and used for the first time as the lubricant for h-BN@PSDA/EPs.

Molecular Resolution Nanostructure and Dynamics of the Deep Eutectic Solvent-Graphite Interface as a Function of Potential.

Interest in deep eutectic solvents (DESs), particularly for electrochemical applications, has boomed in the past decade because they are more versatile than conventional electrolyte solutions and are low cost, renewable, and non-toxic. The molecular scale lateral nanostructures as a function of potential at the solid-liquid interface-critical design parameters for the use of DESs as electrochemical solvents-are yet to be revealed. In this work, in situ amplitude modulated atomic force microscopy complemented by molecular dynamics simulations is used to probe the Stern and near-surface layers of the archetypal and by far most studied DES, 1:2 choline chloride:urea (reline), at the highly orientated pyrolytic graphite surface as a function of potential, to reveal highly ordered lateral nanostructures with unprecedented molecular resolution.