(English) Robot surgeons and artificial life: the promise of tiny machines

The 2016 Nobel Prize in chemistry has been awarded for the design and synthesis of the world’s smallest machines. The work has overtones of science fiction, but holds huge promise in fields as diverse as medicine, materials and energy.

All grand endeavours start small.

This is especially true of efforts to develop nano-scale machines (1,000 times smaller than the width of a human hair), which are always destined to remain tiny however big our ambitions for them grow.

It’s difficult to trace the development of molecular machines to one person or scientific step.

But a 1959 lecture by the celebrated physicist Richard Feynman is as good a point as any.

His talk, given at an American Physical Society meeting in California and titled Plenty of Room at the Bottom,  , laid the conceptual foundations for nanotechnology.

In it, he also anticipated one of the most widely discussed applications for molecular machines – in nano-robotic surgery and localised drug delivery.

“Although it is a very wild idea, it would be interesting in surgery if you could swallow the surgeon,” Feynman told the audience.

“You put the mechanical surgeon inside the blood vessel and it goes into the heart and ‘looks’ around. It finds out which valve is the faulty one and takes a little knife and slices it out.”

This concept didn’t take long to appear in science fiction, including the 1966 film Fantastic Voyage,  in which a submarine crew are miniaturised and injected inside the body of a scientist in order to save him.

Fifty years on, we haven’t succeeded in turning this particular fiction into reality. But the promise is still very much alive. It is hoped, for example, that tiny mechanical delivery systems could one day be injected into the body to deliver toxic chemotherapy drugs directly to the tumour, without harming healthy tissues.

But, as one of the three 2016 chemistry laureates, Sir Fraser Stoddart, told the BBC: “This doesn’t happen overnight; it takes a very long time and hundreds of very talented postdocs.”

At the time Richard Feynman was thinking about manipulating matter at tiny scales, chemists were already laying the groundwork.

In the 1950s and 60s, they were trying to link chemical ring-shapes together in chains, in a bid to come up with new advanced molecules. But early progress faded as scientists struggled to produce enough of these molecules to justify the complex methods.

“One of the biggest challenges these days is fighting antibiotic resistance developing in bacteria,” said Tibor Kudernac, who completed his PhD under the guidance of Ben Feringa, and is now an assistant professor at the University of Twente in the Netherlands.

“This could be one way – to activate the antibiotics only for transient amounts of time when they need to be active in our bodies. But by the time they leave our bodies, they would already be inactive.”

Another use might be in light-driven molecular actuators, which convert energy into mechanical motion. These could have uses in the field of soft robotics, which eschews metals for lightweight, flexible materials.

“If you need to manipulate fragile or sensitive objects – including humans’ internal organs in the future – you don’t want a robotic arm grabbing on them. You would rather have a very soft touch. Molecular-based systems are ideal for these kinds of future applications,” Dr Kudernac told the BBC News website.

A longer-term aim is to mimic some of the biological machinery inside the cell, such as that used when cells divide.

This could potentially find uses in the burgeoning discipline of synthetic biology, which aims to redesign life, or even build artificial organisms.

“One of the main characteristics of life is cellular division. We would really like an artificial cell that can self-divide,” said Dr Kudernac.

“We have no idea how to do this in synthetic systems, so that is the next challenge. We can use these artificial cells to learn how life came about, but also to synthesise complicated chemical compounds.”