Lay summary

Self-assembly of amphiphilic block copolymers in aqueous media is a powerful tool for the development of new, soft materials that are able to express well-defined functions. Here we plan to synthesize new amphiphilic ABC triblock copolymers with an inert, electrically neutral and water- soluble block A and a responsive block C. Structural changes of the self-assembled superstructures will be induced by external triggers and followed in situ. For example, a reversible membrane inversion in ABC triblock copolymer vesicles could indicate thermodynamic stability of such partices. In addition the potential of these systems as triggered release devices for bioactive compounds will be evaluated.

Specific interactions at block copolymer membranes will be systematically studied in solution and at surfaces using recently introduced Ni-NTA functionalized block copolymers. It is expected that the dense array of binding sites at membrane surfaces can induce the formation of highly ordered arrays of his-tagged proteins. Such arrays could find interest as tools in structural biology for membrane protein characterization or as new devices for biosensing. The experiments will serve as a basis to synthesize, characterize and compare also selective binding of folate and mannose terminated polymers that might be interesting for targeted delivery of drugs.

In addition block copolymer vesicles will be used as compartments for the generation of covalently crosslinked hydrogels in their inner aqueous cavity. It is expected that the hydrogels act as a mimic of the cytoskeleton of biological cells and will modify the structure and the mechanical behavior of the vesicles. Responsive hydrogels can be used to trigger structural changes in the system, that will be followed in situ and that could also be used for initiating release of encapsulated materials. Moreover hydrogels will be modified with anchor sites for transmembrane proteins. We expect that successful protein binding to the inner gel will significantly affect the lateral mobility of the proteins in the polymer membranes. First experiments with polymer vesicles loaded with actin filaments would help to take the systems one step further towards a cell mimetic system.

Channel protein equipped block copolymer vesicles (‘nanoreactors’) in solution and at surfaces provide a nanometersized compartmentalization that will be used to study enzymatic reactions down to a single enzyme level. Of particular interest will be to evaluate the effects of spatial confinement and/or molecular crowding inside the nanoreactors on the activity of the encapsulated enzymes.