Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 19: Posters - Membranes and Vesicles

BP 19.5: Poster

Montag, 7. März 2016, 17:30–19:30, Poster C

Investigating Phagocytic Particle Uptake into Giant Unilamellar Vesicles using Photonic Force Microscopy — •Nicolas Schudell and Alexander Rohrbach — Lab for Bio- and Nanophotonics, University of Freiburg

Particle binding and possible particle uptakes are ubiquitous in cell biology starting and controlling a manyfold of processes. In particular, the immunological process of phagocytosis, the engulfment of a solid particle by a cell, eliminates debris and pathogens by a yet unknown amount of physical and chemical energy. The complex uptake mechanism and the different forces involved in it are only partly understood. In order to unveil the mechanistic principles, GUVs are used as a simplistic biomimetic model of a cell. They allow to investigate the important role of the lipid membrane during particle uptake. Here, we use a Photonic Force Microscope (PFM), based on optical tweezers and ultrafast 3D tracking, to approach an 1 um trapped latex bead to an immobilized GUV, until the uptake occurs. The PFM allows quantifying the position fluctuations of the trapped particle during the uptake process in 3D and with nanometer precision. Thereby, we are able to record force and energy profiles, as well as changes in the viscous drag and stiffness of the membrane. A Helfrich energy model for global and local deformation was developed for the comparison with our experimental data.