Molecular machines – science fiction?

Written by Science

Professor David Leigh from University of Manchester stood in front of the Newcastle University audience on Tuesday 8th October. He held a bright pink napkin in his right hand and placed it inside the left fist. We all could see it was gone as soon as he opened his hand. That was one of many magic tricks presented to the open Daedalus lecture’s audience in the Boiler House that day.

The topic of his lecture, molecular machines, might seem to be a concept closer to magical science fiction than reality. The thought of building a shuttle or a car only a few nanometres wide might be unimaginable, and certainly was no longer than 50 years ago, when supramolecular chemistry got recognized. The Nobel Prize was awarded to J. M. Lehn, D. J. Cram and C. J. Pedersen in 1987 and first thoughts about artificial molecular machines started to form in chemists’ heads.

So what do we mean by the term “molecular machine”? It is an assembly of molecules able to perform mechanical-like movement. An example of a “molecular machine” is Rotaxane. This molecule consists of two elements not bonded to each other: a ring and an axle capped on both ends. Just like in our macroworld: the parts could not be separated without breaking one of the bonds, but they are two separate items. With the aid of so-called weak interactions, the ring can be held on one end of the axle and then, in response to a specific signal (i. e. visible light), be moved it to the opposite end. That is how a light-controlled molecular machine can be constructed.

In fact, the example depicted above – the molecular shuttle – was one of the first molecular machines prototyped by Professor J. F. Stoddard in 1991. In 2016 himself, J. P. Sauvage and B. L. Feringa were awarded the Nobel Prize in Chemistry for the design and synthesis of molecular machines. Since the first attempts of creating the machines, designs became more advanced. The possibilities seem to be endless and the examples vary from molecular motor to a nanocar. However, the technology is relatively new and more research is needed before using it in real-life applications.

Professor Leigh’s group is one of many teams in the world exploring possibilities and limitations of molecular machines. During the lecture he presented some of the concepts his group researches, such as nanomotors, molecular assemblers and molecular robotics in an incredibly engaging way, supported by visuals and, of course, magic tricks. He emphasised the fact that humans did not invent molecular machines. All biological functions depend on molecular motion and many of them on biological machines like ATP synthase or ribosomes. They are incredibly complex and not yet understood, therefore it is crucial to investigate into biological systems in order to design better artificial assemblies.

Research in molecular machines is in a brand new realm of science, there is still a lot to be discovered. With that in mind, the question professor Leigh left his audience with might cause a deep reflection  – How will the technology look like 40 years from now? I’m afraid we can’t even imagine.

Last modified: 18th October 2019

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