Potential of mean force of DNA guided assemblies past Debye-Hückel regime

Many of the bioinspired systems make use of biopolymers such as polypeptides or DNA. The latter is widely used in self-assembled systems, from colloidal crystals to origami construction. In these systems, salt is commonly required to screen the electrostatic repulsion between the strands. In the classical Debye-Hückel picture, salt ions are point particles and the screening distance is a decreasing monotonic function of salt concentration. This picture breaks down at moderate salt concentrations, where the behavior becomes non-monotonic. In this talk, we will show results for potential of mean force of DNA grafted colloids obtained through multiscale molecular dynamics. In this picture, the highly charged DNA causes non-trivial behavior at moderate salt concentrations ($c\sim 0.3 - 0.7$M), namely increase of repulsion for non-complementary DNA strands while repulsion decreases for complementary strands. We will show spatial cluster distribution as function of size and charge as well as implications for experimental systems.