Cells are complex, multi-compartmentalized entities of matter enclosed with a variety of membrane-bound organelles ranging from the microscale (µm) down to the nanoscale (nm) in diameter. These structures intermingle in a crowded aqueous phase known as the cytoplasm, within which diffusion deviates from Brownian motion. Understanding the concept of “cell crowding” and the impact on intracellular mobility can enable controlled diffusion within cells for improved drug delivery and other medical applications. The eukaryotic cytoplasm is a biphasic poroelastic (fluid and solid interaction) medium, containing a fluid phase (cytosol with water and soluble proteins) and a solid phase (cytoskeleton and other organelles).