Sliding tubules: adding additional degrees of freedom to anneal self-assembled DNA origami structures*

Self-assembly of structures that have complex geometries, such as open crystalline lattices, shells, or tubules, requires subunits with valence-limited interactions to correctly orient the subunits within the structure. However, valence-limited interactions can limit subunit mobility within an assembly, preventing them from annealing out of off-target structures. Introducing new degrees of freedom can alleviate these kinetic traps. In this talk, I will describe how we apply these ideas to reduce polymorphism in self-assembled tubules. We assemble tubules from DNA origami subunits with specific interactions and binding angles. Despite targeting a single tubule geometry, thermal fluctuations allow a variety of tubule types to form. Since subunits lack mobility, tubules cannot relax to equilibrium even as they grow and accumulate internal elastic stress. To overcome this challenge, we tweak the interactions to create sliding modes within the assemblies. We find that these new modes allow the tubules to anneal towards the target structure. These results show how including additional degrees of freedom can promote annealing towards equilibrium, thereby reducing polymorphism as we strive to make more complex structures.