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Detection of DNA on nanotubes offers
new sensing, sequencing technologies
Kloeppel, Physical Sciences Editor
photo to enlarge
by L. Brian Stauffer
Strano, professor of chemical and biomolecular engineering,
and Esther Jeng, a graduate research assistant, have
found that DNA-wrapped nanotubes can be used to target
specific DNA sequences.
— Researchers at the University of Illinois at Urbana-Champaign
who recently reported that DNA-wrapped carbon nanotubes could serve
as sensors in living cells now say the tiny tubes can be used to target
specific DNA sequences. Potential applications for the new sensors range
from rapid detection of hazardous biological agents to simpler and more
efficient forensic identification.
In the Jan. 27 issue of the journal Science, chemical
and biomolecular engineering professor Michael Strano and his students
reported that single-walled carbon nanotubes coated with DNA could be
placed in living cells and detect trace amounts of harmful contaminants.
In a paper accepted for publication in the journal Nano Letters, and
posted on its Web site, the researchers report they have taken the technique
a significant step further.
“We have successfully demonstrated the optical detection of selective
DNA hybridization on the surface of a nanotube,” said Strano,
who is also a researcher at the Beckman
Institute for Advanced Science and Technology and at the university’s Micro and Nanotechnology Laboratory.
“This work opens possibilities for new types of nanotube-based
sensing and sequencing technologies.”
In its natural state, DNA is in the double stranded form, consisting
of two complementary strands, each resembling the side of a ladder and
having a specific sequence of nucleotide bases as rungs. Hybridization
refers to the spontaneous binding of two complementary strands through
base pair matching.
By wrapping one strand of DNA around the surface of a carbon nanotube,
the researchers can create a sensor that is targeted for a particular
piece of complementary DNA. When the complementary DNA then binds to
the DNA probe, the nanotube’s natural near-infrared fluorescence
is shifted slightly, and can readily be detected.
“The optical detection of specific DNA sequences through hybridization
with a complementary DNA probe has many potential applications in medicine,
microbiology and environmental science,” said Esther Jeng, a graduate
student at Illinois and the paper’s lead author. “For example,
this system could be used in genomic screening to detect sequences that
encode for genetic disorders, and that are precursors to diseases such
as breast cancer.”
“Optical detection allows for passive sensing of hybridization,
meaning there is no need to pass voltage or current through the system,”
Jeng said. “Furthermore, optics yield high-resolution signals
and require a relatively simple setup. And, because our detection setup
is in solution, we can sense in a natural biological environment.”
Co-authors of the paper with Strano and Jeng are undergraduate students
Joseph Gastala, Anthonie Moll and Amanda Roy. The work was funded by
the National Science Foundation.
note: To reach Michael Strano, call 217-333-3634; e-mail: email@example.com.