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