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BP: Fachverband Biologische Physik
BP 5: Membranes and Vesicles I
BP 5.4: Vortrag
Montag, 17. März 2025, 12:15–12:30, H46
Structural and mechanical properties of lipid monolayers at the water-air interface — •Hyunyou Kim1, Ivo Buttinoni1, Laura Alvarez Frances2, and Pantelis Mpourazanis3 — 1Institute of Experimental Physics of Condensed Matter, Heinrich-Heine University, Universitätsstr.1, 40225 Düsseldorf, Germany — 2University of Bordeaux, CNRS, CRPP, UMR 5031, 33600 Pessac, France — 3Fraunhofer IOSB, Gutleuthausstraße 1, 76275 Ettlingen, Germany
Lipid monolayers play a crucial role at air-water interfaces of body, such as in alveoli, where they regulate surface tension. When surface pressure increases, the interface transitions from liquid-expanded (LE) to liquid-condensed (LC) phases.
As experimental model, Dipalmitoylphosphatidylcholine (DPPC) and Cholesterol (Chol) are used. Langmuir-Blodgett trough monitors lipid monolayers during compression, while fluorescence microscopy visualizes the domains. Rheology is measured at various frequencies using an interfacial shear rheometer coupled with trough.
During compression, pure DPPC monolayers transition from LE to LC, with a plateau at surface pressure Π = 5-6 mN/m and collapse at Π = 60-65 mN/m. The domain shape changes from round to fractal. Adding Chol lowers the collapse pressure (Π = 45-50 mN/m) and eliminates the plateau when Chol exceeds 8.6 mol %. Rheology shows that Chol decreases surface viscosity and makes the monolayers more elastic at higher frequencies.
Keywords: lipid monolayer; isotherm compression; rheology