Berlin 2018 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 28: Single Molecule Biophysics
BP 28.10: Vortrag
Donnerstag, 15. März 2018, 12:15–12:30, H 1058
Antenna-enhanced fluorescence correlation spectroscopy resolves calcium-mediated lipid-lipid-interactions — •Stephan Block1,2, Srdjan S. Aćimović1, Nils Odebo Länk1, Mikael Käll1, and Fredrik Höök1 — 1Chalmers University of Technology, Göteborg, Sweden — 2Freie Universität Berlin, Berlin, Germany
Fluorescence correlation spectroscopy (FCS) has provided a wealth of information on the composition, structure, and dynamics of cell membranes. However, it has proved challenging to reach the spatial resolution required to resolve biophysical interactions. Herein, we form artificial cell membranes on dimeric, nanoplasmonic antennas, which shrink the FCS probe volume down to the 20 nm length-scale. By analysing fluorescence bursts from individual fluorescently tagged lipids moving through the antenna hot spots, we show that the confinement of the optical readout volume below the diffraction limit allows the temporal resolution of FCS to be increased by up to 3 orders of magnitude. Employing this high spatial and temporal resolution to probe diffusion dynamics of individual dye-conjugated lipids, we further show that lipid molecules diffuse either as single entities or as pairs in the presence of calcium ions. Removal of Ca2+ by addition of EDTA almost completely removes the complex contribution, in agreement with previous theoretical predications on the role of Ca2+ in mediating transient interactions between zwitterionic lipids. We envision that antenna-enhanced FCS will enable to resolve a broad range of challenging membrane biophysics questions, such as stimuli-induced lipid clustering and membrane protein dynamics.