A tiny turbine made from DNA looks like a windmill and is hundreds of times smaller than most bacteria. It rotates when immersed in salty water and could be used as a molecular machine for speeding up chemical reactions or transporting particles inside cells.
at Delft University of Technology in the Netherlands and his colleagues created the turbine after being inspired by a rotating enzyme that helps catalyse energy-storing molecules in our cells. They wanted to build a molecular machine that could similarly do work, like adding energy to biological processes or moving other molecules, without having to be repeatedly pushed or manipulated in some way.
To create the turbine, the team used a technique called DNA origami in which DNA molecules were loaded onto scaffolds and stuck into a twisted shape. The final structure had an axle and three windmill-like blades. At 25 nanometres in size, it is roughly 2000 times thinner than a human hair.
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When immersed in salty water, the nanoturbine rotated at about 10 revolutions every second due to electromagnetic interactions between salt ions and the DNA. This autonomous movement was exactly what the researchers were after.
鈥淭his is not that different than an engine you have in your car,鈥� says Dekker. 鈥淵ou put in gasoline, you get mechanical work. With the nanoturbine, you add the salt mixture, you get mechanical work, namely rotations.鈥� The researchers also found that they could power the turbine by exposing it to electric voltage or having flowing water turn it much like wind turns a windmill.
The nanoturbine could be used as a tiny propeller for transporting particles. This could be useful for moving drugs within small blobs of fat inside cells, for example. Its rotation could also be used to combine molecules more forcefully in a reaction.
at the Technical University of Munich in Germany says that making the nanoturbine 鈥渇rom scratch鈥� and seeing it in action is a technological achievement. 鈥淐reating a nanoturbine was in the minds of many scientists in the past and this is the first-time demonstration that it actually works.鈥�
However, the analogy between large and tiny turbines isn鈥檛 exact, says at the University of Maine. He says that nano-sized objects experience relatively more friction as they move through fluids and that they are always at the mercy of random thermal fluctuations, so their overall behaviour is difficult to control. Molecular machines must be designed for conditions specific to the nanoscale, says Astumian.
Dekker says that he and his colleagues may have encountered new nanoscale phenomena as they aren鈥檛 certain why the direction of the nanoturbine鈥檚 rotation changes when the water is saltier. They are investigating this with the help of detailed computer simulations. The nanoturbine could be a probe for new physics of the tiny, says Dekker.
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