Nanotechnology breakthrough: DNA turbine changes direction with salt

The researchers wanted to mimic these natural turbines using DNA origami, which uses DNA strands to fold into complex 3D shapes. They designed a rotor with a diameter of 25 nanometers and eight blades that can be right-handed or left-handed. The rotor is attached to a rigid rod and placed in a nanopore, a tiny hole in a membrane that creates a strong water flow when an electric field or a salt gradient is applied.

"We used our nanoturbine to drive a rigid rod up to 20 revolutions per second," says Xin Shi, the study's lead author. "What is fascinating is that the direction of rotation can be reversed by changing the salt concentration in the solution. This is because the salt ions interact differently with the DNA blades depending on their handedness, creating an asymmetry that affects the torque on the rotor."

This phenomenon is unique to the nanoscale and has not been observed before. It is explained by molecular dynamics simulations performed by the group of Aleksei Aksimentiev at the University of Illinois and theoretical modeling by Ramin Golestanian at MPI Göttingen. The researchers believe that this discovery opens up new possibilities for nanotechnology, as it could enable the design of nanomachines that can switch between different functions or modes by changing the salt concentration.

DNA origami nanomachines

One potential application is drug delivery, where DNA origami nanomachines could carry drugs to specific targets in the body and release them by changing their shape or motion. Another possibility is biomimetics, where DNA origami nanomachines could mimic natural molecular motors and perform transport, synthesis, or sensing tasks.

The research was supervised by Cees Dekker, who collaborated with Hendrik Dietz from the Technical University of Munich. They had previously developed a DNA origami nanorotor that could spin continuously in one direction using electrical or salt gradients. The new nanoturbine is an improvement over the previous design, allowing more control over the rotation and integration with other nanomachines.

"We have demonstrated the fundamental principles of propelling a nanoscale rotor using water and salt in nanopores," says Shi. "This year's breakthrough, driven .by rational design, marks the next phase of our journey. The foundational principles from our previous paper, combined with the innovations in this one, set the stage for the future of biomimetic transmembrane machines, with the potential to harness energy from salt gradients, a vital energy source employed by biological motors."

The study was published in the journal Nature.