Weak molecular interactions promote dynamic hierarchical structures

In nature, hierarchical structures, such as protein assemblies inside and outside cells, often dynamically reorganize and display unique functions at different times. Two of us recently created a synthetic system with such capability, using peptide–DNA supramolecular nanostructures that can organize reversibly into hydrogel networks containing bundles of twisted fibers. Here we present a study of the underlying mechanism of this system based upon coarse-grained simulations. Notably, we demonstrate that weak inter- and intra-fiber interactions promote hierarchical order by enabling large-scale redistribution of DNA-containing monomers, a phenomenon not permitted in conventional materials that crosslink at predetermined “linker sites.” We explore the desired energy scales of the cohesive interactions, and provide insights that permit realization of similar dynamic hierarchical behavior in other supramolecular materials. Lastly, we explain the twisted morphology of the fiber bundles, which turns out to originate from kinetic arrest rather than from DNA chirality.