Elastin-like Polypeptide Diblock Copolymers Self-Assembleinto Weak Micelles.

The self-assembly of synthetic diblockcopolymers has been extensivelystudied experimentally and theoretically. In contrast, self-assemblyof polypeptide diblock copolymers has so far been mostly studied experimentally.We discovered that the theory developed for synthetic diblock copolymerdoes not fully explain the self-assembly of elastin-like polypeptidediblock copolymers, leading us to generalize the theory to make itapplicable for these polypeptides. We demonstrated that elastin-likepolypeptide diblocks self-assemble into weak micelles with dense coresand almost unstretched coronas, a state not previously observed forsynthetic diblock copolymers. Weak micelles form if the surface tensionat the core–corona interface is low compared to that expectedof a micelle with a dense core. The predictions of the theory of weakmicelles for the critical micelle temperature, hydrodynamic radius,and aggregation number of elastin-like polypeptide diblocks are inreasonable agreement with the experimentally measured values. Theunique and unprecedented control of amphiphilicity in these recombinantpeptide polymers reveals a new micellar state that has not been previouslyobserved in synthetic diblock copolymer systems. [ABSTRACT FROM AUTHOR]