(14d) Rapid Actuation and Tunable Control of DNA-Based Mechanisms

Precise robotic motion is ever-present within our cells in dynamic proteins like ATP synthase and kinesin. Functioning much like macroscopic machines, these proteins have multiple components and defined motion paths. Engineers across many disciplines use inorganic- and bio-materials to create nano- and micro-robots with similar functionality. Structural DNA nanotechnology enables researchers to design and build DNA-based structures with nanometer-scale spatial control by employing well understood DNA base pairing and nucleic acid synthesis methods. Our early work contributed to a library of DNA devices with controllable motion pathways, primarily using DNA handles and strand invasion to bind or displace reconfigurable components with timescales of minutes or longer. Here, we present two strategies for actuating DNA-based mechanical devices in near real time. First, we demonstrate an approach using a simple modification to existing devices that adds a network of weak binding sites on complementary components for environmentally controlled rapid actuation. A network of weak DNA handles is activated by increasing cation concentration, which raises the avidity of the network to join the two components. Likewise, reconfiguration is quickly reversible in decreased salt conditions. Second, we present an innovative method for real-time actuation using a magnetic stimulus. Micron-scale rigid arms couple magnetic beads to nanoscale devices for direct manipulation through an externally applied magnetic field. This level of spatiotemporal control over DNA devices can serve as a foundation for real-time manipulation of molecular systems.