Self-assembled DNA liquids
Prof. Omar Saleh, University of California Santa Barbara
Living organisms create a variety of complex materials through self-assembly processes, in which soft biomacromolecules (e.g. nucleic acids, proteins) form functional structures through non-covalent binding interactions. Recently, there has been interest in the self-assembly of liquid droplets of biomacromolecules, frequently called ‘membraneless organelles’ in the biological context, though also termed ‘coacervates’. I will discuss our efforts to study this by exploiting DNA nanotechnology to create DNA particles that phase separate into liquids. Formation of liquids, rather than gel aggregates, depends sensitively on the internal flexibility of the DNA particles. Our engineered system displays unusual properties, including the ability to create several distinct liquid phases in a single solution, then to tailor interactions between the phases. Further, the relatively stiff nature of the constituent DNA strands causes the liquid to be extraordinarily tenuous, with the liquid phase having a DNA volume fraction of only ~2% (the rest being water). This opens the possibility to activate the material by infusion of the liquid with proteins; we use this to create mimics of active structure formation in chromatin.