Fabrication of a Membrane Interferometer Containing Electrodes

Abstract

Despite the advantages of supported lipid membranes, one remaining problem has been the incorporation of membrane proteins, as membrane proteins tend to lose their functionality near a surface. To address this limitation but retain the advantages of a nearby surface, we have developed a system where a lipid bilayer is separated a few hundred nanometers from an atomically flat mirror (Ganesan and Boxer, PNAS, 2009, vol. 106, p. 5627). This mirror allows the use of Fluorescence Interference Contrast Microscopy (FLIC) and Variable Incidence Angle-FLIC (VIA-FLIC), two surface characterization techniques that precisely locate the height of fluorescent objects relative to the silicon surface with nanometer resolution. Both FLIC and VIA-FLIC have been used to measure changes in curvature of the bilayer in response to osmotic perturbations of the solution above the bilayer. Current work focuses on changing the architecture of the substrate to allow access to the volume both above and below the bilayer. These changes to the substrate will enable concurrent electrical and optical measurements of voltage-gated membrane proteins, as well as increased control over osmotic balance. Progress towards this goal will be described.