Enzyme kinetics in salt resistant complex coacervate emulsions*

Research in protocells has burgeoned in recent decades due to their fundamental importance in the origin of life and their latent technological potential. Complex coacervates formed by liquid-liquid phase separation of charged macromolecules can be simplistic protocellular models with a distinct interface, spontaneous biomolecular sequestration, and chemical conversions within macromolecularly crowded environments. While the bulk material properties of such coacervates are well understood, this knowledge is yet to be applied towards tailoring protocell design. A major limitation was the long-term stabilization of the liquid-liquid interface, which we previously demonstrated using comb-polyelectrolytes (cPEs). In this talk, we demonstrate that this approach is generic and works with distinct polymer characteristics and salt identities, over a wide range of concentrations. We show improved salt resistance of droplets, tunable by cPE concentration and an expansion of the two-phase window. Furthermore, enzyme mediated reactions yielding bioluminescent molecules delineating reaction kinetics within coacervates will be shown. Finally, the effect of coencapsulation of enzymes on kinetics in cascading reactions within optimized protocellular characteristics will be presented.