Temperature-Dependent Complex Coacervation of Engineered Elastin-like Polypeptide and Hyaluronic Acid Polyelectrolytes

Coacervates have enormous potential due to their diverse functional properties supporting a wide number of applications in personal care products, pharmaceuticals, and food processing. Normally, separation of coacervate phases is induced by changes in pH, ionic strength, and/or polyelectrolyte concentration. This study investigates the microphase separation and coacervate complex formation of two natural polyelectrolytes, elastin-like polypeptides (ELPs) and hyaluronic acid (HA), as simple models for biological coacervates. These complex coacervates are formed over a wide range of stoichiometric molar charge ratios without the presence of salt or changes in pH and are primarily induced by changes in temperature. Unlike pure ELP solutions, the ELP/HA coacervates result in well-formed spherical particles after the temperature-induced phase transition. We also note that the formation of these complex coacervates is reversible with low hysteresis. We have demonstrated via fluorescent imaging and dynamic light...