(482e) Imaging Lipid Distribution within Lipid Membranes Using Nanoscale Secondary Ion Mass Spectrometry

Imaging the lateral distributions of cholesterol, specific lipid species, and proteins is in the plasma membrane at the 50 ? 200 nm lateral resolution that is relevant to membrane organization is currently a major challenge. Though the distributions of membrane proteins can be unambiguously visualized by immunogold labeling and transmission electron microscopy (TEM), our understanding of how lipids and sterols are organized in the plasma membrane and the forces that drive this organization is poor. We previously demonstrated that the distributions of two isotopically labeled lipids within phase-separated model lipid membranes can be imaged and quantified with a lateral resolution of 100 nm using a nanoscale secondary ion mass spectrometry (nanoSIMS) approach. NanoSIMS performed with the NanoSIMS 50 (Cameca Instruments) reveals the elemental and isotopic composition in a sample with a lateral resolution as high as 50 nm. By incorporating a distinct stable isotope into each lipid species of interest, the isotopically enriched secondary ions produced during nanoSIMS analysis encode for component identity. Here we discuss the application of nanoSIMS to imaging the lipid and cholesterol distribution within more complex biological membranes.