Driving biomolecular droplets through polymer meshes

Abstract

Biomolecular condensates are commonly thought as being formed through phase separation from a dilute bulk phase. However, inside cells, biomolecular condensates reside in crowded environments or dense polymer meshes (e.g., cytoskeleton or nucleoskeleton plus chromatin). To characterize the effects of such dense polymer meshes, here we used optical tweezers to trap and drive biomolecular droplets through the meshes formed by a synthetic polymer, Ficoll70. The movement of solid polystyrene beads requires the displacement of Ficoll70 chains and thus encounters the full viscous resistance.