Controlling the dynamics of artificial nucleic acid condensates*

Living cells regulate many of their vital functions through membraneless compartments that phase separate (condense) dynamically in response to different types of stimuli. Taking inspiration from Nature, artificial condensates that can adapt to stimuli could promote the development of "living" biomolecular materials. I will discuss our work toward developing artificial biomolecular condensates whose dynamics of formation and dissolution can be controlled through chemical reactions or external inputs. To build condensates we use nucleic acid molecules folding into star-shaped (nanostar) subunits, that interact through specific complementary domains leading to the formation of phase separated droplets. We have demonstrated how condensate formation can be controlled by modulating the valency of nanostars through strand hybridization and strand displacement. Further, we have developed strategies to initiate condensation using light as a stimulus, making it possible to fine-tune the growth rate of condensates depending on the irradiation dose. Our experimental results are supported by coarse grained simulations illustrating the role of valency in determining the capacity of subunits to phase separate.