Rate-dependent dynamics of cellular membranes probed by laser tweezers and optical displacement sensing

摘要

In this study, we investigated nanomechanical properties of cell membranes in response to elongation at different rates. Membrane nanotubes (tethers) were pulled at different pulling rates by an optically-trapped fluorescent microsphere as the pulling probe. The force relaxation responses of the membrane tethers were recorded and analyzed for low (1 μm/s) and high (100 μm/s) pulling rates. The force relaxation response of membrane nanotubes exhibited a bi-phasic behavior including fast and slow relaxation processes at low and high pulling rates. The fast and slow force relaxation time constants were 0.388±0.21 s and 11.74±3.35 s, in response to pulling rate of 1 μm/s, respectively and significantly decreased at higher pulling rates. These reductions in the time constants are suggestive of reduced viscous effects and weakened adhesions between the membrane and the cytoskeleton during rapid pulling.