Effect of the presence of domains on the stiffness of lipid monolayers

N. WILKE, CARUSO B., MANGIAROTTI A

Carlos Paz

Congreso; XLII Reunión Anual de la Sociedad Argentina de Biofísica; 2013

The compressibility of monolayers composed of two lipids with low lateral miscibility was determined with the aim of investigating the effect of the mechanical properties of each phase on the stiffness of the composite. In nine different systems, the stiffness of each phase and the texture at the plane of the monolayer were studied and the results are discussed in the light of the following two hypotheses: a. The stiffness of the composite is a weighted sum of the stiffness of each phase, regardless of the distribution of the phases in the plane of the monolayer; b. The stiffness of the composite is dominated by the mechanical properties of the continuous phase. Our results were better explained by this latter proposal, as in all the analyzed mixtures it was found that the mechanical properties of the percolating phase were the determining factors1. On the other hand, the effect of the presence of domains in the dilute regime did not follow a common trend. This different behavior did not correlate with different domain−domain interactions or differences in the shape/size of the domains between the systems. We hypothesize that the differences are a consequence of the cooperativity of the percolation process in each monolayer. References: 1- Caruso B., Mangiarotti A., Wilke N. Langmuir 2013, 29, 10807-10816.