CPOS Seminar: Investigating Confined Thermodynamics of Liquid-Liquid Phase Separation using Electrochemistry

Speaker: Nick Watkins, PhD - Elings Postdoctoral Fellow, Department of Chemistry and Biochemistry, Sepunaru Group, UC Santa Barbara

Liquid-liquid phase separation, or coacervation, is a general phenomenon that describes the separation of two immiscible aqueous phases. In biological systems, coacervation of biomolecules, such as mRNA, can occur in response to stimuli such as heightened stress levels or increased small-molecule substrate concentrations. The coacervate phase is often formed by the association of poly-cationic and -anionic molecules and exhibits altered properties from the bulk (e.g. a change in pH, small-molecule enrichment or exclusion, depletion of water) in order to facilitate a response. An aspect of particular interest is the enabling or acceleration of chemical transformations by coacervates, thus posing the hypothesis that the first proto-enzymes were coacervate droplets. In our work, we are using the well-defined electrochemical redox probe ferri/ferrocyanide to investigate how reactant confinement into the coacervate alters the thermodynamics of a reaction. Furthermore, we extend our investigation to the electrochemistry of biologically-relevant flavin mononucleotide, a precursor to FADH, to understand how the effects of confinement can be magnified in multi-proton and -electron transfer reactions. From these data, we look to provide more context for how the solvation environment within the confines of the coacervate facilitates lowered reaction barriers and therefore accelerated reaction rates.