Madhvacharyula, A. S.; Li, R.; Swett, A. A.; Du, Y.; Simmel, F. C.; Choi, J. H.

Structural designs inspired by physical and biological systems have been previously utilized to develop advanced mechanical metamaterials. These are based on the clever geometric arrangement of their building blocks, resulting in enhanced mechanical properties such as shape morphing and auxetic behavior. Until now, the benefits from such designs have yet to be leveraged at the nanoscale. Here, we use the DNA origami method to realize a nanoscale metastructure exhibiting mechanical frustration, the mechanical counterpart of the well-known phenomenon of magnetic frustration. We show that this DNA metastructure can be precisely controlled to adopt either frustrated or non-frustrated mechanical states, each characterized by a distinct free energy profile. Switching between the states is achieved by engineering reconfigurable struts into the structure. Actuation of the struts causes a global deformation of the metastructure. In the non-frustrated state, strain can be distributed homogeneously throughout the structure, while in the frustrated state, strain is concentrated at a specific location. Molecular dynamics simulations reconcile the contrasting behaviors of the two modes and provide detailed insights into the mechanics. Our work demonstrates how combining programmable DNA self-assembly with mechanical design principles can overcome engineering limitations encountered at the macroscale, enabling the development of dynamic, deformable nanostructures with tunable responses. These may lay the foundation for mechanical energy storage elements, nanomechanical computation, and allosteric mechanisms in DNA-based nanomachinery.