Salt Dependent Characteristics of DNA droplets*

We investigate the salt-dependent behavior of self-assembled, liquid droplets of DNA. The droplets are composed of four-armed DNA nanostars. Each arm terminates in a palindromic sticky end that allows the nanostars to bind to each other, creating self-assembled networks. Inserting a single stranded gap before each sticky end increases the flexibility of the nanostar-nanostar connections. This flexibility makes network rearrangement more accessible and causes the DNA network to condense into liquid droplets. We examine the sedimentation of liquid droplets and compare it to droplet size to determine DNA volume fraction within the droplets. The volume fraction of DNA within the droplets increases with salt concentration, consistent with a screening effect. We discuss models of this behavior, and compare our results to other biomolecular coacervate systems.