Significance: Folding DNA into complex 3D shapes (DNA origami) has emerged as a powerful method for the precise design and fabrication of self-assembled nanodevices. Current efforts have focused largely on developing static objects or structures with small movements and/or unspecified motion paths. Here we establish a basis for developing DNA-based nanomachines by creating dynamic mechanisms with well-defined motion. We demonstrate the design of nanoscale 1D, 2D, and 3D motion by integrating concepts from engineering machine design with DNA origami nanotechnology.

Recent and future advances enabling the design of mechanical properties and dynamic behavior of DNA nanostructures will greatly expand the functional scope of DNA-based devices.

DNA nanotechnology has enabled complex nanodevices, but the ability to directly manipulate systems with fast response times remains a key challenge. Current methods of actuation are relatively slow and only direct devices into one or two target configurations. Here we report an approach to control DNA origami assemblies via externally applied magnetic fields using a low-cost platform that enables actuation into many distinct configurations with sub-second response times. The nanodevices in these assemblies are manipulated via mechanically stiff micron-scale lever arms, which rigidly couple movement of a micron size magnetic bead to reconfiguration of the nanodevice while also enabling direct visualization of the conformation. We demonstrate control of three assemblies—a rod, rotor, and hinge—at frequencies up to several Hz and the ability to actuate into many conformations. This level of spatiotemporal control over DNA devices can serve as a foundation for real-time manipulation of molecular and atomic systems.

Wet-dry cycling on the early Earth is thought to have facilitated production of molecular building blocks of life, but its impact on self-assembly and compartmentalization remains largely unexplored. Here, we investigate dehydration/rehydration of complex coacervates, which are membraneless compartments formed by phase separation of polyelectrolyte solutions. Solution compositions are identified for which tenfold water loss results in maintenance, disappearance, or appearance of coacervate droplets. Systems maintaining coacervates throughout the dehydration process are further evaluated to understand how their compartmentalization properties change with drying. Although added total RNA concentrations increase tenfold, RNA concentration within coacervates remains steady. Exterior RNA concentrations rise, and exchange rates for encapsulated versus free RNAs increase with dehydration. We explain these results in light of the phase diagram, with dehydration-driven ionic strength increase being particularly important in determining coacervate properties. This work shows that wet-dry cycling can alter the phase behavior and protocell-relevant functions of complex coacervates.