Polymersomes: Tough vesicles made from diblock copolymers

Vesicles were made from amphiphilic diblock copolymers and characterized by micromanipulation. The average molecular weight of the specific polymer st udied, polyethyleneoxide-polyethylethylene (EO40-EE37), is several times gr eater than that of typical phospholipids in natural membranes. Both the mem brane bending and area expansion moduli of electroformed polymersomes (poly mer-based Liposomes) fell within the range of Lipid membrane measurements, but the giant polymersomes proved to be almost an order of magnitude toughe r and sustained far greater areal strain before rupture. The polymersome me mbrane was also at Least 10 times Less permeable to water than common phosp holipid bilayers. The results suggest a new class of synthetic thin-shelled capsules based on block copolymer chemistry.