The formation of lipid-based hollow, spherical nanocapsules is reported. Polymerizable phospholipids equipped with divinylbenzoyl functionality in their headgroup region are synthesized to explore their polymerization behavior in vesicles. Polymerizable phospholipids alone or as mixtures with phosphatidylcholine produced vesicles as an aqueous dispersion and produced stable nanocapsules upon polymerization at room temperature. These structures survived lyophilization and a redispersion cycle and maintained their structural integrity in nonaqueous solvent. Vesicles were used for encapsulating enzymes in their hydrophilic cores.