In this thesis we investigated intra- and extra-cellular dynamics with the help of optical tweezers and confocal imaging.

Firstly, we measured in vivo diffusion inside endothelial cells by tracking lipid granules and compared the results to in vitro diffusion of polystyrene beads in wormlike micelles.

Furthermore, we studied F-actin dynamics in, and curvature sensing of, a receptor and its ligand on artificially pulled membrane tethers.

Force measurements between a cell and an approaching optically trapped bead were conducted in order to probe the endothelial cell's glycocalyx.

Finally, investigations of force generation by living cells embedded in 3D matrices, conducted in Alexander Dunn's lab at Stanford University, are described in the last chapter.