Artificial protein block polymer libraries bearing two SADs: effects of elastin domain repeats.

We have generated protein block polymer EnC and CEn libraries composed of two different self-assembling domains (SADs) derived from elastin (E) and the cartilage oligomeric matrix protein coiled-coil (C). As the E domain is shortened, the polymers exhibit an increase in inverse transition temperature (T-t); however, the range of temperature change differs dramatically between the EnC and CEn library. Whereas all polymers assemble into nanoparticles, the bulk mechanical properties of the EnC are very different from CEn. The EnC members demonstrate viscolelastic behavior under ambient conditions and assemble into elastic soft gels above their T-t values. By contrast, the CEn members are predominantly viscous at all temperatures. All library members demonstrate binding to curcumin. The differential thermoresponsive behaviors of the EnC and CEn libraries in addition to their small molecule recognition abilities make them suitable for potential use in tissue engineering and drug delivery.