title: Electroformation of Giant Unilamellar Vesicles: Investigating Vesicle Fusion versus Bulge Merging.
abstract: Partially ordered stacks of phospholipid bilayers on a flat substrate can be obtained by the evaporation of a spread droplet of phospholipid-in-chloroform solution. When exposed to an aqueous buffer, numerous micrometric buds populate the bilayers, grow in size over minutes, and eventually detach, forming the so-called liposomes or vesicles. While observation of vesicle growth from a hydrated lipid film under an optical microscope suggests numerous events of vesicle fusion, there is little experimental evidence for discriminating between merging of connected buds, i.e., a shape transformation that does not imply bilayer fusion and real membrane fusion. Here, we use electroformation to grow giant unilamellar vesicles (GUVs) from a stack of lipids in a buffer containing either (i) nanometric liposomes or (ii) previously prepared GUVs. By combining different fluorescent labels of the lipids in the substrate and in the solution, and by performing a fluorescence analysis of the resulting GUVs, we clearly demonstrate that merging of bulges is the essential pathway for vesicle growth in electroformation.
authors.affiliation: Institut Charles Sadron, Université de Strasbourg, UPR22-CNRS , 23 rue du Loess, 67034 Strasbourg, France.|Programa de Pós-Graduação em Química, Instituto de Química, Universidade Federal do Rio Grande do Sul , Porto Alegre 90040-060, Brazil.
authors.forename: Yasmine Miguel Serafini
authors.initials: YM
authors.lastname: Micheletto
authors.affiliation: Institut Charles Sadron, Université de Strasbourg, UPR22-CNRS , 23 rue du Loess, 67034 Strasbourg, France.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Marques
authors.affiliation: Programa de Pós-Graduação em Química, Instituto de Química, Universidade Federal do Rio Grande do Sul , Porto Alegre 90040-060, Brazil.
authors.forename: Nádya Pesce da
authors.initials: NP
authors.lastname: Silveira
authors.affiliation: Institut Charles Sadron, Université de Strasbourg, UPR22-CNRS , 23 rue du Loess, 67034 Strasbourg, France.
authors.forename: André P
authors.initials: AP
authors.lastname: Schroder