This talk will cover work in my laboratory over the past decade on the molecular design of genetically encoded stimulus responsive elastin-like polypeptides (ELPs). Below a characteristic inverse transition temperature (Tt), ELPs –peptide polymers composed of VPGXG repeats– are soluble in aqueous solution, but when the temperature is raised above their Tt, they desolvate and undergo phase separation. We have exploited ELPs to create stimulus responsive nanostructures via three approaches. In the first approach, we have designed diblock ELPs with two ELP blocks with different hydrophobicity’s that self-assemble into spherical micelles with an increase in temperature above the critical micellization temperature of the diblock polymer. I will introduce the concept of “blockiness’’ in block copolymer design and demonstrate how it can be used to tune the morphology of self-assembled nanostructures. In a second approach, we have encoded multiple copies of hydrophobic residues with the sequence (VPGXG)n(XGG)8 where X = W, Y, or F and show that these highly asymmetric amphiphiles self-assemble into rod-like micelles depending on the specific hydrophobic residue. Finally, we have recently shown many of the canonical self-assembling peptides in peptide amphiphiles (PAs) can act as sites for in vivo myristoylation. By appending these peptides at the N-terminus of an ELP, we can recombinantly synthesize fatty acid modified ELPs that can be programmed to exhibit combined and synergistic properties of both ELPs and Pas, such as thermal responsiveness and hierarchical self-assembly.

Self-assembly of stimulus responsive biohybrid polymers

253rd National Meeting (2017)

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