Angew. Chem. Int. Ed.http://doi.org/fz4rft (2012)

Polymersomes — vesicles formed from the assembly of amphiphilic block copolymers — are known to encapsulate a variety of molecular guests including enzymes, DNA and drug molecules. For biomedical applications, the controlled release of such guests is an important characteristic and, so far, the permeability of their membranes has been be tuned by, for example, altering the chemical structure of the polymeric building blocks or the solution pH. Now, Giuseppe Battaglia, Brigitte Voit and colleagues have shown that pressure-induced changes also affect the permeability of polymersomes. They synthesized a family of pH-sensitive, photo-crosslinkable polymersomes and show that formation of pores within the membrane, and hence the selective release of different-sized dendritic molecules, can be controlled by the shear rate applied to the polymersomes. The crosslinked membrane has a more intrinsic resistance to pore formation. Moreover, by changing the solution pH, the transport of reagents to an enzyme encapsulated within the polymersomes can be controlled, even in the absence of transmembrane proteins.