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The Nobel Prize in Chemistry 2016 is awarded to Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard L. Feringa for their development of molecular machines that are a thousand times thinner than a hair strand.
Definition: A molecular machine, or nanomachine, is any discrete number of molecular components that produce quasi-mechanical movements (output) in response to specific stimuli (input). The expression is often more generally applied to molecules that simply mimic functions that occur at the macroscopic level.
How molecules became machines How small can you make machinery? This is the question that Nobel Laureate Richard Feynman, famed for his 1950s’ predictions of developments in nanotechnology, posed at the start of a visionary lecture in 1984. One possible way would be to build a pair of mechanical hands that are smaller than your own, which in turn build a pair of smaller hands, which build even smaller hands, and so on, until a pair of miniscule hands can build equally miniscule machinery. This has been tried, said Feynman, but without great success. Another strategy, in which Richard Feynman had more faith, would be to build the machinery from the bottom up. Nanotechnology - the creation of structures on the scale of a nanometer, or a billionth of a meter - has been a field of fruitful research for a couple of decades. In this next wave of research, scientists are learning how to construct tiny moving machines, about one-thousandth the width of a strand of human hair.
Sauvage produced the first breakthrough in this effort in 1983, when he succeeded in producing two ring-shaped molecules linked by an easily manipulated mechanical bond. This was the first time chemists had manufactured a molecule that could be manipulated in this way.
In 1991, Stoddart reinvented the wheel on a microscopic scale. The machine was eventually used to build a “molecular abacus” that could store information.
Feringa built on both of these breakthroughs to create the world's first molecular motor, a tiny spinning blade that rotates continually on an axis, in 1999. That molecule was developed into a “nanocar,” whose four wheels rotate to move the microscopic structure forward along a plane, like a minuscule car with four-wheel drive. Feringa also showed that the molecule could be used to rotate a glass rod thousands of times larger than the motor itself.
Classification of Molecular machines: Molecular machines can be divided into two broad categories; synthetic and biological.
Synthetic machines: Operating on a scale a thousand times as small as the width of a human hair, these “machines” are specially designed molecules with movable parts that produce controlled movements when energy is added.
Examples of synthetic molecular machines
Molecular motors are molecules that are capable of unidirectional rotation motion powered by external energy input. A number of molecular machines have been synthesized powered by light or reaction with other molecules. A molecular switch is a molecule that can be reversibly shifted between two or more stable states. The molecules may be shifted between the states in response to changes in e.g. pH, light, temperature, an electric current. Molecular tweezers are host molecules capable of holding items between its two arms. The open cavity of the molecular tweezers binds items using non-covalent bonding including hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, p-p interactions, and/or electrostatic effects. Examples of molecular tweezers have been reported that are constructed from DNA and are considered DNA machines.
The construction of more complex molecular machines is an active area of theoretical research. Whereas biology has perfected its machines over billions of years of evolution, chemists keen to imitate these structures are just getting started.
Biological molecular machines: Biology uses them for absolutely everything – from harvesting energy from the sun to the way that we see, with proteins being the most complicated of the lot. Scientists have taken to calling them machines because, just like those designed by humans, they produce mechanical motion in response to an input, allowing them to perform a task.
Example of biological molecular machines The most complex molecular machines are proteins found within cells. These include motor proteins, such as myosin, which is responsible for muscle contraction, kinesin, which moves cargo inside cells away from the nucleus along microtubules, and dynein, which produces the axonemal beating of motile cilia and flagella. These proteins and their nanoscale dynamics are far more complex than any molecular machines that have yet been artificially constructed.
Potential: Compared with the machines that changed our world following the industrial revolution of the nineteenth century, molecular machinery is still in a phase of growth. However, just as the world stood perplexed before the early machines, such as the first electric motors and steam engines, there is the potential for a similar explosive development of molecular machines. In a sense, we are at the dawn of a new industrial revolution of the twenty-first century, and the future will show how molecular machinery can become an integral part of our lives.
They could one day go to work in the human body: Chemists hope that one day these mini machines could be developed so they can deliver drugs within the human body directly to cancerous cells or target a specific area of tissue to medicate. When it’s perfected, this method should greatly reduce the damage treatment such as chemotherapy does to a patient’s healthy cells.
They could event detect disease before it show any symptoms: Recent research into molecular machines has suggested that as well as killing cancer cells or transporting molecules for medical reasons, they could one day lead to the design of a molecular computer which could be placed inside the body to detect disease before any symptoms are exhibited.
They may one day be used to build new materials, operate microscopic sensors and create energy-storage mechanisms too tiny to be seen with the naked eye. Some labs have already succeeded in using molecular machines to produce tiny peptide assembly lines and more-resilient plastics (including a film that can endure being beaten by a hammer).
So, 32 years after Feynman’s visionary lecture, we can still only guess at the thrilling developments ahead of us. However, we do have a definite answer to his initial question – how small can you make machinery? At least 1,000 times thinner than a strand of hair.
By: Dr. Vivek Rana ProfileResourcesReport error
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