DNA association-enhanced physical stability of catanionic vesicles composed of ion pair amphiphile with double-chain cationic surfactant

Divergent Effects of Cholesterol on the Structure and Fluidity of Liposome and Catanionic Vesicle Membranes

Lipid-like ion-pair amphiphile vesicles, or catanionic vesicles, have emerged as potential drug carriers. The effects of cholesterol on the properties of catanionic vesicles have not yet been systematically studied. Here, we compared the effects of cholesterol on the structures and fluidities of dipalmitoylphosphatidylcholine liposomes and catanionic vesicles with similar main transition temperatures (T_m ). For liposomes, fluorescence anisotropy (FA) thermograms reveal typical condensing and disordering effects of cholesterol above and below T_m , respectively. In contrast, FA and molecular simulation data reveal that catanionic bilayers below T_m are more fluidic due to shorter alkyl chains. This leads to only condensing effects of cholesterol for catanionic vesicles at all temperatures. Our results provide important insights into the fabrication of catanionic vesicles as novel drug carriers.

Cholesterol Effect on Membrane Properties of Cationic Ion Pair Amphiphile Vesicles at Different Temperatures

This work is focused on the study of the effect of cholesterol on the properties of vesicular membranes of ionic amphiphilic pairs at different temperatures. The hexadecyltrimethylammonium-dodecyl sulfate ionic amphiphilic pair system with the addition of 10 mol % dioctadecyldimethylammonium chloride was chosen for a detailed study of vesicle properties. A large range of cholesterol concentrations (0-73 mol %) in the temperature range 10-80 °C was studied. Under these conditions, the size distribution, the membrane fluidity, and the surface layer were monitored together with the change in the mobility of water in the surface layer. Obtained quantities were correlated with each other and combined into appropriate graphs. It was found that in stable systems that meet the condition of unimodal size distribution with a PDI value lower than 0.3, temperature has virtually no effect on the size of vesicular systems. On the contrary, when studying the hydration and fluidity of the membrane, significant changes in these parameters were found, which, however, do not affect the short-term stability of these vesicular systems. The presented results thus indicate the possibility of adjusting the composition of the vesicular system in terms of fluidity and membrane hydration while maintaining short-term stability and size distribution.

Adsorption of charged macromolecules upon multicomponent responsive surfaces

A predictive model for polyelectrolyte adsorption upon responsive surfaces is presented, decoupling the effect of surface charges and crowders.