First Biomolecular Motors With Metal
Propellers Can Live Inside Cells,
Cornell Nanobiotechnologists Report
ITHACA, N.Y. -- Nanobiotechnologists at Cornell University have
built and pilot-tested the first biomolecular motors with tiny metal
propellers.
Success in fabricating and operating hybrid organic-inorganic
nanodevices the size of virus particles is reported by the Cornell team
of biophysicists and engineers in the Nov. 24 issue of the journal
Science.
Fueled by adenosine triphosphate (ATP, the so-called energy of
cellular life) and spinning nickel propellers at eight revolutions per
second, molecular motors made of ATPase enzyme are said to herald
a new generation of ultrasmall, robotic, medical devices:
"nanonurses" that move about the body, ministering to its needs, for
example, or "smart pharmacies" that detect chemical signals from
body cells, calculate the dose and precisely dispense drugs.
"With this demonstration, we believe we are defining a whole new
technology," said Carlo D. Montemagno, associate professor of
biological engineering and leader of the molecular-motor mechanics.
"We have shown that hybrid nanodevices can be assembled,
maintained and repaired using the physiology of life."
Montemagno credited Cornell graduate student Ricky K. Soong with
assembling the propeller-equipped nanodevices and noted that patent
applications are in place for the relevant technologies.
Other Cornell authors of the Science report, titled "Powering an
Inorganic Nanodevice with a Biomolecular Motor," are research
associates George D. Banchand and Hercules P. Neves; graduate
student Anatoli G. Olkhovets; and Harold G. Craighead, professor of
applied and engineering physics and director of the Cornell
Nanobiotechnology Center. Nanobiotechnology is the relatively new
enterprise to merge living systems, including products of genetic
engineering, with fabricated nonliving materials, such as silicon, at
the "nano" scale, where a nanometer (nm) equals one billionth of a
meter. The Cornell molecular motors have propellers about 750 nm
in length and 150 nm in diameter (whereas viruses range from about
17 nm to 1,000 nm wide).
The little metal propellers were made at the Cornell Nanofabrication
Facility using a sequence of techniques, including electron gun
evaporation, e-beam lithography and isotropic etching. Thin coatings
of attachment chemicals, described in detail in the journal article,
encouraged the propellers essentially to self-assemble with molecules
of ATPase, which were produced from genetically altered Bacillus
bacteria. Mounted on 200-nm-high pedestals and immersed in a
solution of ATP and other chemicals, some of the biomolecular
motors spun their propellers for two-and-a-half hours.
But before the nanodevices take flight, "We need to achieve a higher
level of site occupancy," said Montemagno, noting that "only" five of
the first 400 propeller-equipped motors worked. Some propellers
came loose and flew off. Some motors apparently dropped off their
test pedestals and others never took their places in the first place.
Eventually, the Cornell nanobiotechnologists would like to engineer
biomolecular motors to run on light energy, with photons instead of
ATP. They also plan to add computational and sensing capabilities to
the nanodevices, which ideally should be able to self-assemble inside
human cells.
Cornell scientists are learning to clean away caustic chemicals left
over from the nanofabrication processes with inorganic materials so
that delicate living molecules are not hindered. Then there is the
clumping problem: "These machines are as small as virus particles,"
Montemagno said. "It's hard to prevent them from clumping together.
Remember, this is all new for us -- and for everyone else in this line
of work."
The experiments were funded by the National Science Foundation,
Defense Advanced Research Projects Agency, Department of Energy,
Office of Naval Research, National Aeronautics and Space
Administration and the W.M. Keck Foundation of Los Angeles.
Related World Wide Web sites:
Video image sequences nanopropellers rotating on biomolecular
motors can be viewed as movies at:
http://falcon.aben.cornell.edu/News2.htm after expiration of
publication embargo.
o Montemagno research group: http://falcon.aben.cornell.edu
o Cornell Nanobiotechnology Center: http://www.nbtc.cornell.edu
Editor's Note: The original news release can be found at
http://www.news.cornell.edu/releases/Nov00/propeller.hrs.html
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