Shear-driven motion of supported lipid bilayers in microfluidic channels.

In this work, we demonstrate how a lateral motion of a supported lipid bilayer (SLB) and its constituents can be created without relying on self-spreading forces. The force driving the SLB is instead a viscous shear force arising from a pressure-driven bulk flow acting on the SLB that is formed on a glass wall inside a microfluidic channel. In contrast to self-spreading bilayers, this method allows for accurate control of the bilayer motion by altering the bulk flow in the channel. Experiments showed that an egg yolk phosphatidylcholine SLB formed on a glass support moved in a rolling motion under these shear forces, with the lipids in the upper leaflet of the bilayer moving at twice the velocity of the bilayer front. The drift velocity of different lipid probes in the SLB was observed to be sensitive to the interactions between the lipid probe and the surrounding molecules, resulting in drift velocities that varied by up to 1 order of magnitude for the different lipid probes in our experiments. Since the method provides a so far unattainable control of the motion of all molecules in an SLB, we foresee great potential for this technique, alone or in combination with other methods, for studies of lipid bilayers and different membrane-associated molecules.