Graphene-based transistors could soon help diagnose genetic diseases.*
|Figure: Schematic of a graphene-based field-effect transistor (left) and
an atomic force microscopy image of graphene covered with
single-stranded probe DNA (right).
Researchers in India and Japan have
developed an improved method for using graphene-based transistors to
detect disease-causing genes.
Graphene field-effect transistors (GFETs) can detect harmful genes
through DNA hybridization, which occurs when a ‘probe DNA’ combines, or
hybridizes, with its complementary ‘target DNA.’ Electrical conduction
changes in the transistor when hybridization occurs.
Nobutaka Hanagata of Japan’s National Institute for Materials Science
and colleagues improved the sensors by attaching the probe DNA to the
transistor through a drying process. This eliminated the need for a
costly and time-consuming addition of ‘linker’ nucleotide sequences,
which have been commonly used to attach probes to transistors.
The research team designed GFETs that consist of titanium-gold
electrodes on graphene—a one-atom-thick layer of carbon—deposited on a
silicon substrate. Then they deposited the DNA probe, in a saline
solution, onto the GFET and left it to dry. They found that this drying
process led to direct immobilization of the probe DNA on the graphene
surface without a need for linkers. The target DNA, also in saline
solution, was then added to the transistor and incubated for four hours
for hybridization to occur.
The GFET operated successfully using this preparation method. A
change in electrical conduction was detected when the probe and target
combined, signaling the presence of a harmful target gene. Conduction
did not change when other non-complementary DNA was applied.
DNA hybridization is usually detected by labelling the target with a
fluorescent dye, which shines brightly when it combines with its probe.
But this method involves a complicated labelling procedure and needs an
expensive laser scanner to detect fluorescence intensity. GFETs could
become a cheaper, easier to operate, and more sensitive alternative for
detecting genetic diseases.
“Further development of this GFET device could be explored with
enhanced performance for future biosensor applications, particularly in
the detection of genetic diseases,” conclude the researchers in their
study published in the journal Science and Technology of Advanced
Arun Kumar Manoharan, Shanmugavel Chinnathambi, Ramasamy Jayavel and Nobutaka Hanagata
“Simplified detection of the hybridized DNA using a graphene field effect transistor”
Science and Technology of Advanced Materials, 2017; 18:1, 43-50.
For further information please contact:
Nanotechnology Innovation Station, National Institute for Materials Science, Tsukuba, Japan
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