Pore-Spanning and Multi-Lamellar Lipid Membranes on Engineered Solid Supports

This dissertation concerns two subjects. The first is a report on the formation of pore-spanning lipid bilayers on 130 nm pores in a Si3N4 film supported on a silicon substrate. These lipid membranes self-assemble via vesicle fusion on organosilane-treated Si3N4, forming solvent-free lipid membranes. Membrane fluidity is verified by fluorescence recovery after photobleaching (FRAP) and electrical impedance spectroscopy (EIS) is used to study the electrical resistance, demonstrating membrane resistance in excess of 1 gigaohm. An array of 40,000 membranes demonstrated high impedance over 72 hr, with reduced impedance indicating rupture of some membranes observed at 77 hr followed by nearly complete rupture at 82 hr. Gramicidin was incorporated in the membranes as a model ion channel, and CaCl2 was used to block the gramicidin to demonstrate that the resulting membrane conductance resulted from gramicidin-mediated ion transport. These highly-stable, biologically-functional pore-spanning membranes open many future possibilities for silicon-based ion-channel devices for applications such as biosensors and high-throughput drug-screening.;The second component of this dissertation reports on the development of a myelin sheath analog based upon a multilamellar bilayer. The myelin sheath is among nature's most fascinating nanoscale assemblies. In spite of its critical role in physiology, several questions on the structure-function relationship of myelin and its components remain unanswered. This is chiefly due to the fact that interactions between the constituents of myelin are particularly difficult to study in intact tissue. The compact, multi- lamellar structure of myelin inhibits or limits access to the interacting membrane surfaces. In addition, characterizing the interaction of purified myelin components has provided only limited information on such things as compositional and environmental effects on myelin structure. Thus, there is a tremendous need to develop novel biomimetic systems that can act as experimental models to help understand this critical component of complex neural systems. The multilamellar bilayer assemblies studied here are formed through controlled layer-by-layer assembly via vesicle fusion. Several methods are used to probe the structure and electrical and mechanical properties of the multilamellar bilayer assembly, namely electrical impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy and fluorescence microscopy.