Hydrodynamic shear dissipation and transmission in lipid bilayers

Significance Lipid bilayers constitute the matrix of cellular membranes and synthetic vesicles used in drug delivery. This self-assembled structure is only a few nanometers thick but provides an effective barrier between aqueous fluids. The response of lipid bilayers to shear stresses induced by surrounding fluid flows can trigger biophysical processes in cells and influence the efficacy of drug delivery by synthetic vesicles. Here, we use optical tweezers to apply and measure local hydrodynamic shear stresses on both sides of a freestanding lipid bilayer. With this method, we determine the rheological properties of bilayers and capture a previously unreported phenomenon when the intermonolayer friction is so low that the monolayers slip past each other and hydrodynamic shear is not transmitted through the bilayer.