Regensburg 2013 – scientific programme

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BP: Fachverband Biologische Physik

BP 28: Focus session: Intracellular Spectroscopy

BP 28.5: Talk

Thursday, March 14, 2013, 10:45–11:00, H44

Mapping lipid membrane molecular properties via vibrational imaging of vesicular systems — •Hilton B. de Aguiar and Andreas Volkmer — 3. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart

Probing the physical properties and chemical composition of lipid membranes is of fundamental importance to understand their role on biological cell functioning. Unlike in conventional fluorescence-based microscopies of membranes, which require specific labeling and may perturb the molecular properties of interest, Raman microspectroscopy directly probes the intrinsic vibrational spectral response of the membrane lipids offering the advantage of both chemical specificity and sub-micron spatial resolution in a noninvasive manner. Here, we report on the spatially resolved Raman spectroscopy of vesicular model membranes (Giant Unilamellar and Multilamellar Vesicles). We observe distinct Raman image patterns of an individual vesicle for distinct vibrational modes. We successfully model this sensitivity of the Raman image contrast to the physical properties of the lipids by taking the higher order optical nature of Raman scattering into account. Remarkably, the image patterns turn out to be very sensitive on molecular orientation and order parameters offering the opportunity of membrane structure analysis by label-free Raman microscopy. Furthermore, we demonstrate how the Raman spectral response can be readily used to distinguish between thermodynamic phases (liquid/gel state) and domain composition of membrane lipids.