click to enlarge These are transmission electron microscope images of a nanopore in graphene. The original pore on the left grows considerably under the influence of the electron beam. The image on the right is the spore after four minutes at 800 C. Pores either shrink or grow depending on the temperature and electron beam irradiation.

Engineers at the University of Texas at Dallas
have used advanced techniques to make the material graphene small enough to
read DNA.

Shrinking the size of a graphene pore to less
than one nanometer—small enough to thread a DNA strand—opens the possibility of
using graphene as a low-cost tool to sequence DNA.

“Sequencing DNA at a very cheap cost would
enable scientists and doctors to better predict and diagnose disease, and also
tailor a drug to an individual’s genetic code,” says Moon Kim, professor of
materials science and engineering and senior author of an article published in Carbon.

The first reading, or sequencing, of human DNA
by the international scientific research group known as the Human Genome
Project cost about $2.7 billion. Engineers have been researching alternative
nanomaterials materials that can thread DNA strands to reduce the cost to less
than $1,000 per person.

It was demonstrated in 2004 that graphite
could be changed into a sheet of bonded carbon atoms called graphene, which is
believed to be the strongest material ever measured. Because graphene is thin
and strong, researchers have searched for ways to control its pore size. They
have not had much success. A nanoscale sensor made of graphene could be
integrated with existing silicon-based electronics that are very advanced and
yet cheap, to reduce costs.

In this study, Kim and his team manipulated
the size of the nanopore by using an electron beam from an advanced electron
microscope and in-situ heating up to 1,200 C temperature.

“This is the first time that the size of the
graphene nanopore has been controlled, especially shrinking it,” says Kim. “We
used high-temperature heating and electron beam simultaneously, one technique
without the other doesn’t work.”

Now that researchers know the pore size can be
controlled, the next step in their research will be to build a prototype
device.

“If we could sequence DNA cheaply, the
possibilities for disease prevention, diagnosis, and treatment would be
limitless,” Kim says. “Controlling graphene puts us one step closer to making
this happen.”

Source: University of Texas at Dallas