Fluid dynamics alters liquid-liquid phase separation in confined aqueous two-phase systems

Area of Science:

• Biophysics
• Materials Science
• Chemical Engineering

Background:

• Liquid-liquid phase separation (LLPS) is fundamental to cellular organization and biotechnological applications.
• Controlling droplet morphology in aqueous two-phase systems (ATPS) enables advancements in single-cell analysis, drug delivery, and tissue engineering.
• Previous models often neglect fluid dynamics, potentially misrepresenting phase separation behavior.

Purpose of the Study:

• To develop a computational model of LLPS in ATPS that incorporates fluid dynamics.
• To investigate the influence of buoyancy, surface tension, and shear flows on phase separation dynamics and morphology.
• To provide a more accurate understanding of ATPS evolution for optimizing microparticle production and biological applications.

Main Methods:

• Developed a computational model simulating finite viscosity fluid dynamics with thermally induced phase separation.
• Included buoyancy and surface-tension effects in the model.
• Compared model predictions with experimental data for gelatin-polyethylene glycol mixtures.

Main Results:

• Fluid dynamics significantly alter the evolution and equilibrium of phase separation.
• Buoyancy drives ATPS towards energy-minimizing crescent shapes, contradicting models that neglect fluid dynamics.
• Shear flows can accelerate particle formation by a factor of ten.
• Neglecting fluid dynamics leads to inaccurate predictions of minimum-energy droplet shapes.

Conclusions:

• Accurate modeling of ATPS requires incorporating fluid dynamics, particularly buoyancy.
• The developed model enhances understanding of microparticle formation and ATPS behavior in biological and industrial settings.
• This work facilitates optimization of manufacturing processes for structured microparticles and improves insights into cellular compartmentalization.