First Biomolecular Motors with Metal Propellers Source: Cornell University November 23, 2000
First biomolecular motors with metal propellers are
reported by Cornell nanobiotechnologists report
Details of the first biomolecular motor with a
nanofabricated propeller, as reported in the journal Science,
11/24/00. (A) Electron microscope photo of nanofabricated nickel post,
80 nanometers wide and 200 nanometers tall; (B) drawing of ATPase
biomolecular motor; (C) electron microscope photo of nanofabricated
nickel propellers, about 750 nm long and 150 nm in diameter; (D)
drawing of assembled biomolecular motor (red) and nickel propeller
(green) on nickel post (grey). Montemagno Research Group/Copyright ©
2000 Science. A high-resolution copy of this photo (1352 x 1120
pixels, 1187K) is available here.
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.
"This technology opens the door to hybrid nanodevices that 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.
by Roger Segelken
607-255-9736
hrs2@cornell.edu
http://www.news.cornell.edu/releases/Nov00/propeller.hrs.html