Emulsions and Their Applications in High-Throughput Screening of Proteins

Abstract

Emulsions are liquid two-phase mixtures of a continuous phase and a discrete phase. When two liquid phases do not mix thermodynamically at the molecular level, creating an emulsion provides an approach to disperse one phase into another, so a macroscopically homogeneous mixture can be achieved. As a unique material, emulsions find broad applications in a broad range of industries, such as petroleum, food, cosmetics and healthcare. Due to the large surface area of an emulsion, it resides at a high energy state and is therefore unstable. To prevent emulsions from coarsening in industrial use, surfactant molecules are used to coat emulsion surfaces; surfactants introduce repulsion between two approaching drops to reduce merging. More recently, emulsions have also been recognized as a mechanism that cells use to organize intracellular reactions. In this thesis, we will present the following work. In the second chapter, we discuss our work on an observation of a surfactant-free metastable emulsion system. In the third chapter, we study emulsions in cells, which are biomolecular condensates; we measure the mechanical properties of these condensates once they form. We expect the first half of work in this thesis to enhance the understanding of synthetic and biological emulsions. In the last two chapters, we apply emulsions in a synthetic biology application. By creating droplets with precise size and composition control, we perform high throughput screening assays in them to discover enzyme mutants of industrial interests. This method can aid the discovery biomolecules with desired propertiesas, and be used to generate high quality data for protein engineering.