Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 107: Nanostructured Surfaces and Thin Films

O 107.4: Talk

Friday, March 22, 2024, 11:15–11:30, MA 042

Phase-Resolved Sum-Frequency Generation Microscopy of Lipid Rafts in Model Membranes — •Alexander Fellows, Ben John, Martin Wolf, and Martin Thämer — Fritz-Haber-Institut der MPG, Berlin, Germany

Since the lipid raft model was developed, it became clear that the lateral assembly and packing of phospholipids in cell membranes is a critical parameter controlling their physiological function. However, whilst studies of model systems have observed and characterised many structural aspects of such condensed lipid domains, their exact structure down to the molecular level remains unknown.

Here, we utilise our new advancement in molecular imaging through phase-resolved SFG microscopy to investigate model lipid rafts in lipid monolayers with mixed chirality. Through rotationally-dependent hyperspectral imaging of the lipid domains, we fully determine their 3D structures, showing that their in-plane molecular packing is highly curved and that their mesoscopic structure is part of a hierarchal spiral motif. Furthermore, through enantiotopic substitution measurements, we demonstrate that all aspects of the structural directionality are dependent on the lipid chirality, but importantly also that the formed structures display a clear deviation in mirror symmetry for different chirality mixtures. Such an observation gives an important insight into the enantioselective interactions that dominate many membrane processes.

Keywords: Lipid Monolayer; Sum-Frequency Generation Microscopy; Molecular Imaging