The Phase Behavior of Supported Lipid Bilayer Mixtures and Cell Membranes Imaged By Secondary Ion Mass Spectrometry

Abstract

Supported lipid bilayers have been used as a tool to study the biophysical properties of model membranes with defined compositions. Special attention has been given to the role of cholesterol on the phase behavior of lipid membranes, in particular, to the formation of lipid rafts and complexes. Common techniques used to elucidate the phase behavior of binary and ternary lipid bilayers (i.e. fluorescence and atomic force microscopy) have been limited by their inability to provide direct information on the spatial composition of membranes. Secondary ion mass spectrometry (NanoSIMS) has proved to be a powerful tool for imaging the lateral organization of lipid bilayers with a spatial resolution in the order of tens of nanometers. In this study, a NanoSIMS is used to image lipid bilayers containing isotopically-labeled cholesterol. Additionally, human cell membranes are also imaged.