05/08/2022
Ad Spijkers
Inspired by iconic Dutch windmills and biological motor proteins, researchers at Delft University of Technology in the Netherlands have created a self-configuring, flow-driven turbine from DNA. It converts energy from an electrical or salt gradient into usable mechanical power. The results offer prospects for the development of active robotics at a nanoscale.
Turning turbines have been the powerhouses of human societies for millennia. From the windmill and the waterwheel in the Netherlands to the most advanced off-shore wind turbines that power the future of renewable energy. Spinning motors, driven by flow, are also common in biological cells.
"An example is FoF1-ATP synthase, which produces the fuel cells need to work. However, artificial construction at the nanoscale has remained elusive. Until now", says Dr Xin Shi, postdoc in Prof Cees Dekker's laboratory at TU Delft's Bionanoscience department.
The flow-driven nanoturbine developed in Delft is made of DNA material. The structure is placed on a minuscule opening in a thin membrane. The DNA bundle, only 7 nm thick, then organises itself into a kind of turbine by means of an electric field. This rotor then turns with more than 10 s-1.
DNA origami
The scientists have been trying to build rotating nanomotors artificially for seven years. They use a technique called DNA origami, in cooperation with Technical University of Munich. This technique uses the interactions between complementary DNA base pairs to build 2D and 3D nano-objects.
The nanomotors get their energy from a water and ion flow created by an electrical voltage, or even simpler: by different salt concentrations on the two sides of the membrane. The latter is one of the most common sources of energy in biology, powering several critical processes, such as cellular fuel production and cell locomotion.
The achievement is a milestone, as it is the first time a flow-driven motor has been developed at the nanoscale. When the researchers first saw the rotations, they were puzzled: how could such simple DNA rods show such beautiful, constant rotations?
Clever design
In consultation with the Max Planck Institute for Dynamics and Self-organization in Göttingen (50 km north-east of Kassel) the puzzle was solved. The German scientists modelled the system and revealed the fascinating process of self-organisation. The DNA bundles deform into spiral motors, which then connect to the flow of liquid through the nano hole.
But the significance of the work does not stop with the simple motor itself. The technique and physical mechanism behind it give a whole new direction to building synthetic nanomotors. Flow-driven nanomotors are a surprisingly virgin territory for scientists and engineers. They still know little and what they have achieved about building such nanomotors. This is given the age-old knowledge about building their macro-scale counterparts and the crucial roles they play in life.
In the next step, the researchers used the knowledge they had gained to achieve the next major result: the first rationally designed turbine at the nanoscale. The Delft researchers started with a simple wind turbine, but are now able to recreate wind turbines as small as 25 nm, the size of a single protein in a body. And they have shown that these nanomotors can perform work. The direction of rotation could also be set by the designed spiral.
Steam engine
In addition to a better understanding and replication of motor proteins such as FoF1-ATP synthase, the results offer new perspectives for the development of active robotics at the nanoscale. Shi: "What we have demonstrated here is a motor at the nanoscale that can transfer energy and perform work. You could make an analogy with the invention of the steam engine in the 18th century. Who could have predicted then how it would fundamentally change our societies? We are now in a similar phase: the possibilities are endless, but there is still much work to be done."
The scientific publication can be found here.
Photo: TU Delft, Cees Dekker Lab / SciXel