Micro-engineered liquid-liquid interfaces for assembly of macromolecules

Abstract

Liquid-liquid interfaces play an important role in self-assembly in biological systems. The ability to adsorb and desorb molecules from such interfaces will determine the dynamics of these assembly processes. Traditional synthetic liquid-liquid interfaces are often formed between aqueous solutions and oils. The relatively high interfacial tension and the consequent high adsorption energy make desorption of micron-sized particles and large macromolecules unlikely, without a high energy input. With a significantly reduced interfacial tension, these particles and molecules will exhibit faster dynamics with a milder perturbations. Besides, the adsorption dynamics, the shape of low-interfacial-tension interfaces will also change more readily, giving rise to non-spherical structures characterized by many protrusions. In this talk, I will discuss the use of aqueous two-phase systems to control the assembly of both particles and biomacromolecules. I will describe how aqueous phase separation can give rise to hierarchical multiple droplets, and demonstrate how biomacromolecules and particles can be directed to form stable capsules with large number of protrusions. By tuning the interfacial tension without introducing surfactants or changing temperature, we can control the morphologies of these aqueous two-phase droplets, which show behaviors that are significantly different from the water-oil counterparts, but resemble their biological counterparts. While these observations cannot fully explain the wide variety of structures in biological systems, they may shed light on some underlying mechanisms of aqueous assembly in nature.