Spherically confined Brownian suspensions: influence of locally heterogenous structure on diffusion and rheology*

Spherically confined, hydrodynamically interacting colloids provide a framework for understanding biological cells over length and time scales where interparticle interactions and particle motion play central and nontrivial roles in whole-cell behavior. Under different biological conditions, a cell’s overall size, crowding level, and the strength of electrostatic interactions of its constituent molecules can change. Therefore, it is important to understand how each of these changes alters the physics of biological processes that take place inside cells. In this work, we perform dynamic simulations with both Confined Stokesian Dynamics and Confined Brownian Dynamics algorithms. We disentangle the role of entropic and hydrodynamic effects on short- and long-time transport properties of particles under spherical confinement to better understand differences between real life systems under conditions of weak and strong hydrodynamics. Additionally, we find relationships between rheological properties, such as osmotic pressure and viscosity, and the variables volume fraction and particle size within the confinement.