Active Controlled and Tunable Coacervation Using Side-Chain Functional alpha-Helical Homopolypeptides

We report the development of new side-chain amino acid-functionalized alpha-helical homopolypeptides that reversibly form coacervate phases in aqueous media. The designed multifunctional nature of the side-chains was found to provide a means to actively control coacervation via mild, biomimetic redox chemistry as well as allow response to physiologically relevant environmental changes in pH, temperature, and counterions. These homopolypeptides were found to possess properties that mimic many of those observed in natural coacervate forming intrinsically disordered proteins. Despite ordered alpha-helical conformations that are thought to disfavor coacervation, molecular dynamics simulations of a polypeptide model revealed a high degree of side-chain conformational disorder and hydration around the ordered backbone, which may explain the ability of these polypeptides to form coacervates. Overall, the modular design, uniform nature, and ordered chain conformations of these polypeptides were found to provide a well-defined platform for deconvolution of molecular elements that influence biopolymer coacervation and tuning of coacervate properties for downstream applications.