What do Dutch windmills and biological motor proteins have in common?
Both structures rely on flow-driven rotary motors to produce energy, and both provided inspiration to researchers from Delft University of Technology (TU Delft) in creating tiny synthetic rotary nanomotors from DNA.
Using a technique known as “DNA origami”, which builds 2D and 3D nano-objects from interactions between complementary DNA base pairs, the researchers were able to build a structure of DNA of only 7 nanometres thick, docked onto a nanopore (a tiny opening in a thin membrane).
Under the influence of a flow – such as that coming through the nanopore – this bundle of DNA self-assembles “into a rotor-like configuration and begins a sustained rotary motion of more than 10 revolutions per second”, says Dr. Xin Shi, first author of the publication in Nature Physics, at TU Delft.
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The flow itself can be produced through an applied electric field or simply by having different concentrations of salts on either side of a cell membrane (a key energy source in biological processes).
Exactly why the DNA rods were able to self-organise and rotate in this way was a bit of a mystery to the research team, until models of the system revealed the evolution of chirality (“handedness” or unique directionality) in the bundles of DNA which couple to the nanopore flow.
Understanding the coupling between flow and rotor self-organisation is, in itself, is a major discovery with important ramifications for future research of flow-driven nanoturbines – whether robotic or biological in nature. “You would be surprised how little we knew about building such flow-driven nanoturbines, especially given the millennia-old knowledge we have on building their macroscale counterparts, and the critical roles they fulfill in the life itself”, says Shi.
The research team has already taken new steps with their nanorotors, creating Dutch windmill-inspired multi-armed rotors, but, says Shi, “this time with a size of only 25 nm, the size of one single protein in your body.”
Armed with the ability to control the rotation direction of the rotors, the team hope to investigate energy production via active nanorobotic engines based on some of the more common motor proteins in the body.