Nature is a veritable machine shop. In the cells and structures of every living organism lie motors, pumps, assembly lines, tiny vehicles, and other far more sophisticated versions of the machinery we have created for ourselves to do work.
Now we’re mimicking nature’s 4 billion years of evolution to manufacture on the scale of atoms. Chemistry typically takes a brute force approach to make molecules: mix and isolate compounds, add catalysts and chemicals, then wait until the right chemicals have formed. It’s difficult and inefficient compared to the elegant molecular machines that biology has designed to manufacture its exotic compounds for life.
Now, scientists are taking the cue. Individual molecules are being designed to serve as primitive nano-machines whose shape and properties allow them to venture out into a chemical solution, or living cells, and repeatedly perform tasks. Eventually, it is hoped, these new molecules will lead to more efficient and cost-effective manufacturing systems at the atomic level.
One of the latest breakthroughs, published this month in the journal Nature is a nanorobot that grabs six amino acids, similar to how robotic arms manipulate parts in car factories, and reassembles these in a sequence known as a peptide. The team, drawn from the universities of Manchester and Edinburgh in the U.K., relied on a structure similar to a molecular axle with a ring threaded on it--known as a rotaxane--to let a molecular machine travel along the axle, grab each amino acid and then chain them together.
The machine, says David Leigh of the University of Manchester and co-author of the study, is a very primitive version of the ribosome, the protein manufacturing center of the cell, and is the first step to start making a machine that can manufacture complex custom molecules such as the drug penicillin. But for now, it is barely functional compared to the speed and sophistication of its biological inspiration. Leigh’s team needed 12 hours and a billion squared molecular machines (that’s 1 with 18 zeros) to make just a few milligrams of peptide. Compared to the ribosome, the artificial machines take hours instead of seconds, can only make simple proteins, and destroy the underlying molecule in the process.
Yet scientists are making rapid progress. In the last few years, synthetic molecular machines are starting to adapt mechanical principles from rotors, gyroscopes, scissors, wheelbarrows, and cars, as well as cribbing off the blueprint proved by nature by using the principles of biochemistry and physics.