Steric-Induced Effects on Stabilizing a Lamellar Structure

• Published in: Langmuir Vol. 29; no. 45; pp. 13717 - 13722
• Main Authors: Gerbelli, Barbara B, Rubim, Rafael L, Silva, Emerson R, Nallet, Frédéric, Navailles, Laurence, Oliveira, Cristiano L. P, de Oliveira, Elisabeth A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12-11-2013
• Subjects: Cell Membrane - chemistry; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Lecithins - chemistry; Lipid Bilayers - chemistry; Membranes; Surface physical chemistry; Surface-Active Agents - chemistry; Composition; Fluctuations; Incorporation; Swelling; Lipids; Cosurfactant; Fatty acids; Bilayer; Lamellar structure; Steric effect; Phosphatidylcholine; Membrane; X ray scattering; Interface
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la402962c

We investigate the behavior of multilamellar phases composed of lecithin and a commercial cosurfactant (Simusol), which is a mixture of ethoxylated fatty acids. Using X-ray scattering and a new procedure to fit the data, relevant parameters characterizing the lamellar structure were determined as a function of membrane composition, varying from 100% of lecithin to 100% of Simulsol. Scattering data illustrating the swelling of the lamellae for different amounts of cosurfactant are presented with the respective behavior of the Caillé parameter. With this experimental approach, we show that the incorporation of ethoxy brushes onto the lipid surface enhances repulsive interactions arising from membrane fluctuations and changes the interactions at the interface between bilayers.