Formation and Gelation of Elastin-like Polypeptide Complex Coacervates

Protein liquid-liquid phase separation underlies the formation of membraneless organelles in cells and performs a key role in the assembly process of natural materials such as the assembly of tropoelastin into elastic fibers. Here, we engineered a series of charged elastin-like polypeptides (ELPs) that form complex coacervates, providing a rapid method to concentrate proteins into a fluid state. Compared to coacervates formed from simple coacervation, complex coacervates exhibited greater fluidity, likely due to differences between electrostatic interactions and hydrophobic forces. We designed these ELP’s to further contain crosslinking domains compatible with tyrosinase or transglutaminase and found that crosslinking was enhanced when proteins were in a complex coacervate compared to free in solution. Crosslinking the ELP complex coacervates led to the formation of gels with distinct properties dependent on the nature of the crosslinking. This work expands the design space of ELP hydrogels, offering a novel strategy for forming crosslinked networks from complex coacervates and providing opportunity for future use in tissue engineering and biocompatible biomaterials applications.