Unjamming of Multiphase DNA Liquids in 2D

Living systems have evolved the ability to modulate mechanical properties across multiple scales by coupling biochemistry to physical mechanisms that can adapt, reconfigure, and strengthen in response to changes in the mechanical environment. For example, inside cells, biological condensates assemble and coarsen even in complex, crowded environments, and on the multicellular scale, tissues undergo a jamming phase transition from fluid to solid. Recently, we discovered a simple model material made up of dense packings of multiphase droplets composed of DNA nanostar liquids. The prototissue exhibits unique dynamics: the same species droplets coalesce, but different droplet species repel each other like hard spheres due to excluded volume interactions. Experiments show that the packing undergoes a solid-to-liquid unjamming phase transition. We examine this phase transition using Brownian dynamics simulations of multicomponent liquid droplets. We find that the sharpness of the unjamming transition depends strongly on biomolecular diversity and stoichiometry. The investigation of these multicomponent model materials may aid in linking hard sphere jamming to more biologically relevant systems, such as tissue mechanics and biological condensate coarsening in complex environments.