Lamellarsomes: metastable polymeric multilamellar aggregates

We report the formation of disperse metastable multilamellar aggregates (lamellarsomes) with size ranging from hundreds of nanometres to hundreds of micrometres. Lamellarsomes are formed by the spontaneous self-assembly of amphiphilic block copolymers in water. Their internal lamellar structure is analysed in detail by transmission electron microscopy by means of fast Fourier transform analysis (FFT) and show features of lyotropic lamellar phase normally stable at high copolymer concentration. These lamellarsomes, although metastable, have long lifetimes and can encapsulate hydrophilic molecules in their enclosed aqueous volumes. Furthermore, the metastable nature of lamellarsomes is shown to modulate release of the encapsulated cargo through the generation of more permeable unilamellar vesicles, on application of mild osmotic shock.