Graphene is pretty amazing stuff. Just a couple of months ago, we heard about how the one-atom thick sheets of bonded carbon atoms had been used to create the strongest pseudo-electric magnetic fields ever sustained in a lab – and that was just the latest use that had been discovered for it. Now, word comes from Harvard University and MIT that graphene could be used to rapidly sequence DNA.
Researchers at Harvard drilled a few-nanometers wide hole, known as a nanopore, in a sheet of graphene. That sheet was stretched over a silicon-based frame, and inserted between two liquid reservoirs. When those reservoirs were filled with water, the graphene sheet was the only barrier between the two bodies of water. At less than one nanometer in width, graphene is the thinnest material known to be able to separate two liquid compartments from one another. That’s actually not too surprising, as it’s also the strongest known material.
Graphene is also electrically-conducive, so when a current was applied to the sheet, it attracted ions in the water toward it. As the ions passed through the nanopore, they registered as a continuous electrical signal. When long DNA chains that had been added to the water went through the opening one-by-one, they blocked the flow of ions, resulting in a change in the electrical signal. The exact nature of those changes allowed the researchers to determine the size of each DNA molecule, and to identify their individual nucleobases, which are the letters of their genetic code.
There are still some hurdles to overcome, such as controlling the speed at which the DNA strands pass through the nanopore, but the scientists believe it could lead to rapid, low-cost DNA sequencing. “We were the first to demonstrate DNA translocation through a truly atomically thin membrane. The unique thickness of the graphene might bring the dream of truly inexpensive sequencing closer to reality,” said Harvard’s Prof. Daniel Branton. “The research to come will be very exciting.”
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