Submicron hybrid vesicles consisting of polymer–lipid and polymer–cholesterol blends

Hybrid polymer–lipid and polymer–cholesterol submicron unilamellar vesicles with a diameter of ∼200 nm based on poly(dimethylsiloxane)-block-poly(2-methyl-oxazoline) (PDMS-b-PMOXA) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) were prepared by using the film-hydration and extrusion method. The vesicles were extensively characterized via dynamic and static light scattering (DLS and SLS), dual-color fluorescence cross-correlation spectroscopy (DC-FCCS), cryogenic transmission electron microscopy (cryo-TEM) and atomic force microscopy imaging and force spectroscopy (AFM). The combination of these techniques provides information about the vesicle size, shape and long-term stability as well as the mechanical properties. DC-FCCS proved the formation of hybrid vesicles containing both components. Cryo-TEM and AFM studies revealed that the presence of cholesterol in vesicle membranes leads to a higher packing density resulting in a reduced membrane thickness and a significantly increased bending stiffness compared to pure polymersomes and polymer–lipid vesicles.