Influence of Side-Chain Molecular Features on Aqueous Coacervation of Multifunctional Homopolypeptides

Three different series of amino acid side-chain functionalized homopolypeptides were prepared as variants of previously reported α-helical, coacervate-forming cationic polypeptides. Studies of the physical behavior of these polypeptides in aqueous media in the presence of multivalent counterions enabled a better understanding of the molecular requirements for coacervate formation of side-chain functionalized homopolypeptides. Variation in lengths of side-chain amino acid or linker segments in cationic α-helical polypeptides was found either to prohibit coacervate formation or to allow adjustment of the phase transition temperature. A series of charge-reversed, anionic amino acid side-chain functionalized homopolypeptides were also prepared and found to be α-helical and able to form coacervates similar to analogous cationic homopolypeptides. These results illustrate the ability to predictably tune coacervation properties via molecular adjustment of side-chains in homopolypeptides and show that amino acid side-chain functionalized homopolypeptides can be used as a general platform for development of biomimetic, coacervate-forming polymers.