The linoleic acid influence on molecular interactions in the model of biological membrane.

The present work explores the properties for binary (LA/DPPC), (cholesterol/DPPC) and also ternary (LA/cholesterol/DPPC) mixed Langmuir monolayers, at the air-water interface, treated as the simplest models of a half of the biological membranes. In ternary monolayers both cholesterol and DPPC were mixed at constant molar ratios that correspond to the proportions occuring in different natural membranes, among which fibroblast membrane (where the amount of phospholipid predominates) and also erythrocyte membrane (where the amount of sterol predominates) were taken into consideration. Our researches were conducted by using the Langmuir film balance, by means of which we registered the surface pressure (pi) as a function of the area of water surface available to each molecule (A).

Cholesterol and phytosterols effect on sphingomyelin/phosphatidylcholine model membranes--thermodynamic analysis of the interactions in ternary monolayers.

In this work thermodynamic analysis of the interactions between lipids in ternary sphingomyelin/DPPC/sterol Langmuir films were performed to compare the effect of cholesterol, beta-sitosterol and stigmasterol on a model membrane. The condensing effect of the respective sterols and the interactions between molecules in ternary mixtures were analyzed on the basis of the excess area per molecule and the excess free energy of mixing values. The stability of the mixed monolayers was verified with the free energy of mixing values.

Differences in surface behaviour of galactolipoids originating from different kind of wheat tissue cultivated in vitro.

The aim of presented researches was to investigate the physicochemical properties of Langmuir monolayer of galactolipids extracted from two different kinds of plastids: immature embryos and inflorescences. Differences between the physicochemical properties of the plastid membranes may help to explain different physiological processes, such as plant regeneration. Surface pressure (pi) vs.

A Langmuir film approach to elucidating interactions in lipid membranes: 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine/cholesterol/metal cation systems.

The interactions between two membrane lipids, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) and cholesterol (CHOL), were studied in Langmuir films using surface pressure isotherms and Brewster angle microscopy. The DPPE/CHOL interactions were probed for chosen monolayer and subphase (Na(+), Ca(2+)) composition at 20, 25, and 30 degrees C. The results obtained show that DPPE and CHOL are miscible for the cholesterol mol fractions x(CHOL)=0.

A study of the interaction of dodecyl sulfobetaine with cationic and anionic surfactant in mixed micelles and monolayers at the air/water interface.

The miscibility and interactions between components in mixed adsorbed films and micelles containing zwitterionic (dodecyl sulfobetaine--DSB) and cationic (dodecyltrimethylammonium bromide) or anionic (sodium dodecyl sulfonate) surfactant, respectively, have been investigated. The molecular interactions have been quantified by the values of the excess free energy of adsorption (DeltaGS,Exc) and micelle formation (DeltaGM,Exc). The obtained results indicate nonideal behavior of the investigated mixtures since the values of DeltaGS,Exc and DeltaGM,Exc) are negative.