STATIC TIME-OF-FLIGHT SECONDARY-ION MASS-SPECTROMETRY IMAGING OF FREEZE-FRACTURED, FROZEN-HYDRATED BIOLOGICAL-MEMBRANES

The study of cell membrane lipid and steroid composition and distribut ion is important for the understanding of membrane dynamics and functi on. Here we present efforts to chemically image phospholipid distribut ions on a submicron scale on freeze-fractured and frozen-hydrated lipo somes and red blood cells using time-of-flight secondary ion mass spec trometry. Sample preparation by freeze fracturing of membranes is desc ribed. Fragments representative of phospholipid headgroups are found t o be localized on both liposomes and red blood cells. In addition, the cholesterol molecular ion [M+H] is localized on liposome surfaces. (C ) 1998 John Wiley & Sons, Ltd.