  We present real-time observations by confocal microscopy of the dynamic
behavior of multilamellar vesicles (MLVs), composed of charged synthetic
lipids, when put in contact with oppositely charged polyelectrolyte (PE)
molecules. We find that the MLVs exhibit astonishing morphological transitions,
which result from the discrete and progressive binding of the charged bilayers
induced by a high PE concentration gradient. Our physical picture is confirmed
by quantitative measurements of the fluorescence intensity as the bilayers bind
to each other. The shape transitions lead eventually to the spontaneous
formation of hollow capsules, whose thick walls are composed of lipid
multilayers condensed with PE molecules. This class of objects may have some
(bio)technological applications.
