WE ARE all aware of atoms. All matter in the universe – including our bodies – are made of atoms. But most of us have never seen an atom. However, due to the advances in technology, the world of atoms has opened up to us as humans.
The voyage into the world of atoms is fascinating. When we get to this microscopically small world, we find new kinds of forces, quantum effects, new possibilities and different optical, electrical and magnetic behaviour. And after many years of research, it now seems that molecular machines made of atoms could change the future. Molecular machines (nanites or nanomachines) are molecular components that produce “quasi-mechanical movements (output) in response to specific stimuli (input).”
In 2016, Fraser Stoddart of Northwestern University in Evanston in the US, Jean-Pierre Sauvage of the University of Strasbourg in France, and Bernard Feringa of the University of Groningen in the Netherlands received a Nobel Prize in chemistry for their pioneering work in the development on nanoscale machines – one thousandth of the width of a human hair. Each of them developed groups of molecules with moving parts that they could control remotely, despite their minute size. In doing so they made numerous future applications of these molecular machines in medicine, computing and engineering possible.
The foundational work by these scientists was done over decades. Already in 1983 Sauvage and his team in France made a molecular machine formed from two interlinked molecular rings, called catenanes. The molecular machines functioned by the rotation of one of the rings with the help of a copper atom that acted as an on-off-switch.
Several years later in 1991, Stoddart and his fellow scientists developed “molecular shuttles”, called rotaxanes, consisting of a molecule with a ring mechanically locked onto an axle that could be guided remotely to different points along the molecular axle by random thermal motion. He further succeeded in the production of molecules that work just like human muscles by extending and contracting dramatically. Later, Stoddart developed a molecular elevator that can move up and down between two stages.
Feringa designed numerous molecular machines that can rotate, since 1994. One well-known example is a molecular version of a four-wheel drive car. He also developed a rotating molecular motor that was able to drive the rotation of a rod 10 000 times larger than the motor.
The importance of the breakthrough of these scientists was, among others, the control of movement. Several scientists and engineers have built on their work and developed innovative products, such as a molecular “pistons”, “clutches”, “windmills”, “elevators”, “wheelbarrows”, and “nanocars”.
Unfortunately, just because a molecule looks like a macroscopic piston or elevator, does not mean that the molecule can necessarily perform a similar function at the molecular level. Matter behaves very differently at different scales. Scientists, therefore, realised that machines need to be designed according to the environment they are intended to operate in.
In the past few years much more useful machines have been made. James Tour and his team from Rice University in Houston in the US, in 2017 made a molecular machine that could drill through cell membranes. The use of molecular machines with short peptide addends allow doctors to deliver drugs directly to a particular location in a patient’s body. In the case of the treatment of cancer, it will limit the therapeutical drugs to a very specific area ensuring precise targeting of cancerous cells and a reduction in side-affects.
The potential is huge that molecular machines will change most things in terms of material design. This is not such a strange idea, since living things use bio-molecular machines to fulfil many tasks. More recently, research started to focus on molecular machines that can make molecules. In biology, for example, ribosomes are bio-molecular machines that assemble proteins. They build molecules called amino acids in a specific sequence to create a vast array of amazing materials, from keratin in our fingernails to the Y-shaped proteins or antibodies of our immune system.
Over the years, Professor David Leigh and colleagues from the University of Manchester in the United Kingdom, have discovered fundamental ways to control molecular-level dynamics and topology such as the synthesising of interlocked molecular architectures, molecular machines, molecular ratchet machines, molecular knotting, molecular assemblers, molecular robotics and molecular weaving.
According to Leigh “the best way to appreciate the technological potential of controlled molecular-level motion is to recognise that nanomotors and molecular-level machines lie at the heart of every significant biological process.”
Nature has chosen this solution to achieve complex task performance for a very good reason. Our ability “to build artificial structures that can control and exploit molecular-level motion, and interface their effects directly with other molecular-level substructures and the outside world,” will in future potentially impact every aspect of functional molecule and materials design.
There is little doubt that molecular machines made of atoms that are carefully constructed molecule by molecule from new materials, could open numerous possibilities for new innovative uses. Based on the rapid advances of the past few years, we are getting close to the essential role played by biological machines in numerous cellular processes. Perhaps Richard Feynman was correct when he said: “What I cannot create, I do not understand.”
Professor Louis CH Fourie is an extraordinary professor at the University of the Western Cape.
*The views expressed here are not necessarily those of IOL or of title sites.
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