Single Molecule Analysis of Biomembrane Heterogeneity

Abstract

The biological membrane is a complex and dynamic structure that participates in many important cellular functions. As such, model membranes are frequently employed to study membrane structure and its relationship to function. In this dissertation, a defocused single molecule analysis technique will be presented and applied to explore several questions of biomembranes structure. First, the role of cholesterol in inducing domain separation in Langmuir-Blodgett films will be investigated as cholesterol is an important lipid raft component. Next, the role of the hybrid lipid POPC will be evaluated in forming and stabilizing small domains to aid in explaining how lipid rafts, which are 10 – 200 nm in diameter, are stable in the complex biological membrane. Two alternative models for membrane structure, spin-coated supported lipid bilayers and droplet interface bilayers, will be presented and evaluated for their unique properties. Finally, a preliminary study for using droplet interface bilayers to investigate important biological problems will be suggested. Through these studies, we will demonstrate the utility of model membranes and defocused single molecule analysis for investigating biomembranes structure.