The combination of block copolymers and phospholipids to form giant hybrid unilamellar vesicles (GHUVs) does not systematically lead to "intermediate" membrane properties.

In this work, the elasticity under stretching as well as the fluidity of Giant Hybrid Unilamellar Vesicles (GHUV) has been studied. The membrane structuration of these GHUVs has already been studied at the micro and nanoscale in a previous study of the team. These GHUVs were obtained by the association of a fluid phospholipid (POPC) and a triblock copolymer, poly(ethyleneoxide)-b-poly(dimethylsiloxane)-b-poly(ethyleneoxide). Although the architecture of triblock copolymers can facilitate vesicle formation, they have been scarcely used to generate GHUVs. We show, through micropipette aspiration and FRAP experiments, that the incorporation of a low amount of lipids in the polymer membrane leads to a significant loss of the toughness of the vesicle and subtle modification of the lateral diffusion of polymer chains. We discuss the results within the framework of the conformation of the triblock copolymer chain in the membrane and in the presence of lipid nanodomains.