Results of atomistic molecular dynamics simulations of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol monolayers at the air/water interface are presented. Dipalmitoylphosphatidylcholine is zwitterionic and dipalmitoylphosphatidylglycerol is anionic at physiological pH. NaCl and CaCl2 water subphases are simulated. The simulations are carried out at different surface densitie...

Films of a water-soluble tetracationic porphyrin (TMPyP) and an insoluble phospholipid (DMPA), in a molar ratio TMPyP:DMPA ) 1:4, were transferred onto optically transparent indium tin oxide (ITO) electrodes, and cyclic voltammetry and visible spectroscopy were used to detected and quantify the presence of porphyrin on the ITO supports. We found the surface density of porphyrin deposited ranges...

Hydrophobicity, the spontaneous segregation of oil and water, can be modified by surfactants. The way this modification occurs is studied at the oil-water interface for a range of alkanes and two ionic surfactants. A liquid interfacial monolayer, consisting of a mixture of alkane molecules and surfactant tails, is found. Upon cooling, it freezes at T(s), well above the alkane's bulk freezing te...

The surface properties of cholesteryl palmitate, stearate, linoleate, linolenate, arachidonate, and acetate were investigated. Long-chain esters were not surface-active and force-area (pi-A) isotherms were not obtained. Unsaturated cholesteryl esters were oxidized at the air-water interface and these oxidized lipids gave expanded pi-A isotherms. Cholesteryl acetate had an equilibrium spreading ...

This paper compares six phospholipidic monolayers at the water/chloroform interface by performing dilational rheological measurements with a drop tensiometer apparatus. The chosen lipids differ both in their headgroup structure and fatty acyl chain saturation or symmetry. The study concentrated on monolayers formed with DPPC, DPPE, DOPC, DOPE, POPC and POPE. Using a generalized Maxwell rheologi...

Freeze-dried systems containing sucrose and organic acids were found to undergo rapid nonenzymatic browning, even at low relative humidities. Addition of protein reduced the rate of browning, especially at low humidities. It was determined that the browning was due to reducing sugars produced by acid-catalyzed hydrolysis of sucrose. This hydrolysis occurred even when water content was well belo...

Langmuir films behavior of asymmetric glycerol dialkyl nonitol tetraether (GDNT) lipids at the air-water interface (temperature 19 ̊C ± 1 ̊C) investigated the stability of the mean ratio of Langmuir films for different spreading time prior to the transfer film. Floating monolayer films stability is an important parameter to obtain high-quality Langmuir-Blodgett films for their aplications. Hyster...

Using the techniques of optical microscopy and particle tracking, we measure the correlated diffusion in a monolayer of uniform silica spheres dispersed at a water-air interface. It is found that the correlated motion of the interfacial particles can be well described by two universal response functions, the normalized longitudinal and transverse diffusion coefficients D(∥)(r/r0) and D(⊥)(r/r0)...

The pathway of interfacial self-assembly of large-scale, highly ordered 2D nanoparticle/polymer monolayer or bilayer arrays from a toluene solution at an air/water interface was investigated using grazing-incidence small-angle scattering at a synchrotron source. Interfacial-assembly of the ordered nanoparticle/polymer array was found to occur through two stages: formation of an incipient random...

We report the results of x-ray reflectivity measurements of thin films formed by different water-soluble proteins at the air-aqueous solution interface. It is demonstrated that glucose oxidase, alcohol dehydrogenase, and urease molecules denaturate at the air-aqueous solution interface to form 8- to 14-A-thick peptide sheets. X-ray reflectivity data indicate that the spreading of a lipid monola...