Substrate-Membrane Interactions: Mechanisms for Imposing Patterns on a Fluid Bilayer Membrane

A variety of new techniques are emerging that require the use of a patterned substrate to impose micropartitions on a supported fluid bilayermembrane. The barrier-forming characteristics of aluminum oxide, indium-tin oxide (ITO), chrome, and gold patterns on silica substrates have been examined. All four materials form effective barriers to lateral diffusion within the supported membrane; however, two distinctly different mechanisms were observed. Aluminum oxide inhibits vesicle fusion, thus restricting membrane formation to the exposed silica surface. In contrast, vesicles will fuse with ITO, chrome, and, to some extent, gold; however, the resultingmembrane is effectively immobile over the time scale of several hours. These materials partition the supported membrane by selectively immobilizing membrane that adsorbs to their surface. The twomechanisms ofmembrane partitioning described here provide additional flexibility in the design and application of micropatterned membranes.