Hydration repulsion dominates the interaction between polar surfaces in water at nanometer separations and ultimately prevents sticking together of biological matter. Although confirmed by a multitude experimental methods for various systems, its mechanism remained unclear. A simulation technique is introduced that yields accurate pressures solvated prescribed chemical potential applied to stack phospholipid bilayers. Experimental pressure data are quantitatively reproduced simulations...

All surfaces in water experience at short separations hydration repulsion or hydrophobic attraction, depending on the surface polarity. These interactions dominate more long-ranged electrostatic and van der Waals are ubiquitous biological colloidal systems. Despite their importance all scenarios where separation is nanometer range, origin of these still unclear. Using atomistic solvent-explicit molecular dynamics simulations, we analyze interaction free energies charge-neutral model with...

A prominent class of osmolytes that are able to stabilize proteins in their native fold consist small highly water-soluble molecules with a large dipole moment and hydrophobic groups attached the positively charged end molecule, for which we coin term dipolar/hydrophobic osmolytes. For TMAO, is prime member this class, perform large-scale water-explicit MD simulations determine bulk solution activity coefficient as well affinity stretched polyglycine chain varying TMAO dipolar strength...

Ionic surfactants are known to build up higher interfacial pressures at oil/water interfaces than air/water for the same surfactant bulk concentration. Here, we systematically investigate this effect through atomistic molecular dynamics (MD) simulations of surfactant-loaded and interfaces. Two prototypical ionic surfactants, C12TAB sodium dodecyl sulfate (SDS), studied found give consistent results, which also robust with respect variations in simulation force field. The reproduce...

A model of the outer membrane Gram-negative bacteria was created by deposition a monolayer purified rough mutant lipopolysaccharides at an air/water interface. The density profiles monovalent (K + ) and divalent (Ca 2+ cations normal to (LPS) monolayers were investigated using grazing-incidence X-ray fluorescence. In absence Ca , K concentration peak found in negatively charged LPS headgroup region. With addition CaCl 2 ions almost completely displaced from By integrating experimentally...

Abstract Membrane systems that naturally occur as densely packed membrane stacks contain high amounts of glycolipids whose saccharide headgroups display multiple small electric dipoles in the form hydroxyl groups. Experimentally, hydration repulsion between glycolipid membranes is much shorter range than zwitterionic phospholipids are dominated by a single large dipole. Using solvent-explicit molecular dynamics simulations, here we reproduce experimentally observed, different...

Polar surfaces in water typically repel each other at close separations, even if they are charge-neutral. This so-called hydration repulsion balances the van der Waals attraction and gives rise to a stable nanometric layer between polar surfaces. The resulting is crucial for properties of concentrated suspensions lipid membranes hydrophilic particles biology technology, but its origin unclear. It has been suggested that surface-induced molecular structuring responsible repulsion,...

Cavitation, the formation of vapor bubbles in metastable liquids, is highly sensitive to nanoscale surface defects. Using molecular dynamics simulations and classical nucleation theory, we show that pure water confined within defect-free walls can withstand extreme negative pressures, far beyond those observed experimentally. Hydrophobic surfaces trigger heterogeneous cavitation lower pressure magnitude, but not experimental levels. Notably, a single nanoscopic defect capable hosting bubble...

Water at negative pressures can remain in a metastable state for surprisingly long time before it reaches equilibrium by cavitation, i.e., the formation of vapor bubbles. The wide spread experimentally measured cavitation depending on water purity, surface contact angle, and quality implicates relevance bulk, surfaces, defects different systems. We formulate kinetic model that includes all three pathways determine nucleation attempt frequencies from atomistic molecular dynamics simulations....

Abstract Magnetite nanoparticles exhibit magnetic properties that are size and organization dependent and, for applications rely on their state, they usually have to be monodisperse. Forming such particles, however, has remained a challenge. Here, we synthesize 40 nm particles of magnetite in the presence polyarginine show composed 10 building blocks, yet diffract like single crystals. We use both bulk measurements induction maps recorded from individual using off-axis electron holography...

Amorphous calcium carbonate (ACC) is a metastable hydrated solid that has received great attention as precursor in crystallization both synthetic and biological systems. In particular, the atomic structure of ACC matter ongoing discussion. Some studies have pointed out similarities between local amorphous its crystalline counterparts, whereas others suggested no resemblance to any known form. Despite large number studies, few structural aspects been described beyond first Ca–O distance...

Interface rheology suggests bacteria blocks antibacterial peptides by forming physically cross-linked gels of lipopolysaccharides in the presence divalent cations.

Surfactants play essential roles in many commonplace applications and industrial processes. Although significant progress has been made over the past decades with regard to model-based predictions of behavior surfactants, important challenges have remained. Notably, characteristic time scales surfactant exchange among micelles, interfaces, bulk solution typically exceed currently accessible atomistic molecular dynamics (MD) simulations. Here, we circumvent this problem by introducing a...

Surface phenomena in aqueous environments such as long-range hydrophobic attraction, macromolecular adhesion, and even biofouling are predominantly influenced by a fundamental parameter-the water contact angle. The minimal angle required for these related to occur has been repeatedly reported be around 65° is commonly referred the "Berg limit." However, universality of this specific threshold across diverse contexts remained puzzling. In perspective article, we aim rationalize reoccurrence...

Lipopolysaccharide (LPS) monolayers deposited on planar, hydrophobic substrates were used as a defined model of outer membranes Pseudomonas aeruginosa strain dps 89. To investigate the influence ions (out-of-plane) monolayer structure, we measured specular X-ray reflectivity at high energy (22 keV) to ensure transmission through water. Electron density profiles reconstructed from curves, and they indicate that presence Ca(2+) induces significant change in conformation charged polysaccharide...

Most land-living organisms regularly experience dehydration. In nature, one commonly applied strategy to protect against this osmotic stress is introduce small polar molecules with low vapor pressure, called osmolytes. Two examples of naturally occurring compounds are urea and trimethylamine N-oxide (TMAO), which known have counteracting effects on protein stability. work, we investigate the TMAO lipid self-assembly at varying water contents, focusing dehydrated conditions. By using...

This paper addresses the effect of polyelectrolyte stiffness on surface structure (P)/surfactant (S) mixtures. Therefore, two different anionic Ps with intrinsic persistence length

Adsorption of surfactants to fluid interfaces occurs in numerous technological and daily-life contexts. The coverage at the interface other properties formed adsorption layers determine performance a surfactant with regard desired application. Given importance these applications, there is great demand for comprehensive characterization understanding layers. In this review, we provide an overview suitable experimental simulation-based techniques review literature which they were used...

The concentration profile of deuterated myoglobin (Mb) adsorbed onto polystyrene substrates displaying poly(ethylene glycol) (PEG) brushes is characterized by neutron reflectometry (NR). method allows to directly distinguish among primary adsorption at the grafting surface, ternary within brush, and secondary brush outer edge. It complements depth-insensitive standard techniques, such as ellipsometry, radioactive labeling, quartz crystal microbalance. study explores effect PEG polymerization...