Storage of mechanical energy in DNA nanorobotics using molecular torsion springs

DNA nanostructures are increasingly used for the realization of mechanically active nanodevices and DNA-based nanorobots. A fundamental challenge in this context is the design of molecular machine elements that connect the rigid structural components and are powered in an effective way. Here we investigate a pivot joint that enables rotational motion of a nanorobotic arm and show the storage and release of mechanical energy by winding up and relaxing the joint that functions as a molecular torsion spring. Using electrical manipulation of the nanorobotic arm and simultaneous observation via single molecule fluorescence microscopy, we study the mechanical properties of various joint designs. Brownian dynamics simulations suggest that breaking of stacking interactions is a major contributor to enthalpic energy storage.