Fig. 1.

Images of giant unilamellar vesicles (GUVs) of DSPC/DOPC/chol reveal compositions where immiscible phases coexist, and other regions where no phase separations are apparent. GUVs were labeled with fluorescent dyes (16:0, Bodipy)-PC (green) and C20:0-DiI (red), both at 0.1 mol%, and observed at 23°C. Examples of GUV appearance are shown in images A, B, C. (A) Open circles indicate uniform fluorescence over the entire GUV observed for both dyes; (B) Filled circles, round domains that show complementary brightness of the two dyes; (C) Filled squares, red domains with clearly angular and linear features are surrounded by green, or else small islands of green are observed within a red background. GUVs with separated domains that show combinations of round and linear features are indicated by triangles. Most experiments used gentle hydration to prepare GUVs, which thus contain 10 mol% PG. But no difference in phase behavior was found for GUVs without PG prepared by electroswelling. Each image is color-merged from the simultaneously collected fluorescence emission from C20:0-DiI and (16:0, Bodipy)-PC using the Leica Confocal software. Images were constructed from confocal microscopy z-scans in 1-μm increments. Scale bars are 5μm.