As awareness of the concept of molecular technology spreads through the
scientific and lay communities, the word "nanotechnology" becomes
ever more fashionable. And, alas, it becomes ever more frequently applied
to something other than its original meaning. The trend reached full flower
recently with a story in Nature (June 5, 1997)—and considerable
related coverage in general media—proclaiming "the first nanomachine,"
a bioelectronic device developed at the Australian Membrane and Biotechnology
Research Institute (AMBRInstitute). See this issue's "Recent
Progress" and "WebWatch" columns for more details.
It was a nice piece of work they did Down Under, but a "nanomachine"
it isn't. "The device harnesses the self-assembly dynamics of the lipid
membrane, and thus provides access to the sensitivity of nanotechnology
using only bench level chemistry," its designers said. This is a significant
development, but not directly on the path toward programmable molecular
assembly.
Associated Press carried another story that further illustrates
the confusion now surrounding the term "nanotechnology. In Ithaca,
NY, researchers at Cornell University carved a guitar out of crystalline
silicon to demonstrate the possibilities of building electromechanical devices
at the nanometric level. Coming just before the 20th anniversary of Elvis
Presley's death, the reports of a "nanoguitar" were well timed,
creating the possibility of Nano-Elvis sightings.
"Building dimensions in nanometers requires a new approach using high-voltage
electron beam lithography. The teeny-weeny musical instrument, dubbed the
nanoguitar, was sculpted out of single crystal silicon," AP reported.
"The strings are each about 50 nanometers wide—the width of about
100 atoms. They could be plucked using the tip of an atomic force microscope."
"I know we can go smaller than this," Cornell Applied and Engineering
Physics Professor Harold Craighead is quoted as saying. "The question
is, how small can we go and still have dependable and measurable mechanical
properties. We are nearing the technological limit where it gets harder
to get smaller than this."
These examples follow a pattern that Foresight Institute has been anticipating
for several years: As the scientific underpinnings of molecular nanotechnology
become better understood within the science community, it becomes more professionally
acceptable for researchers to position themselves as "nanotechnologists."
A first-order consequence will be more widespread confusion about just what
constitutes "nanotechnology." Our recommendation: whenever you
talk to someone about the subject, take the time to provide your definition
of the term, and distinguish "molecular nanotechnology" from the
top-down technologies which sometimes march under the same flag.
Foresight also expects increasing attention to the economic and social issues
which the realization of molecular nanotechnology is expected to bring.
Some of that discussion will embrace Neo-Luddite arguments that nanotechnology
research shouldn't be pursued. Expect this to happen, and understand that
it is part of the process of preparing for nanotechnology, even if it isn't
always comfortable.
Report on Business Magazine, in its June 1997 magazine,
extensively featured Xerox Corp. nanotechnologist Ralph
Merkle in a story entitled, "Beyond the Microchip." Author
Clive Thompson described Merkle's appearance before a conference of microchip
manufacturers last fall in which he described the expected end of Moore's
law as current microchip manufacturing techniques reach their limits.
"If the microchip engineers want to keep increasing computer performance,
they'll need to break out of the box; find totally new ways to create subminiature
chips; write software that thinks in radically different ways," Thompson
wrote. "Otherwise, Merkle thinks, computers won't get faster, memory
won't expand any further and software won't become more powerful. Corporations
of the future would be stuck with the technology of the past."
"When Merkle delivered this message, the engineers stood and cheered."
Foresight Executive Director Chris Peterson is also quoted discussing self-assembly
using chemical reactions as a means to make smaller chips. "We're talking
about designing computer materials the way you design drugs—mixing
molecules together using chemical reactions to create devices," she
is quoted as saying. "All the major chip makers, such as Intel, Motorola
and IBM, have engineers working on this issue," Thompson reports.
The Stewart platform, one of several design
concepts being considered as a basis for a molecular-scale general purpose
assembler, is gaining popularity in the macro world. Fortune
Magazine's May 26 issue writes up "Five Heroes of Manufacturing,"
including New Hampshire-based Hexel Corp., which is marketing a sophisticated
but relatively low-cost programmable machine tool whose design is based
on the Stewart platform. Two other big tool makers, Giddings & Lewis
and Ingersoll, also are bringing "hexapod" machine tools to market,
Fortune reported; two Japanese companies plan to join the fray
soon. Inventor Paul Sheldon, who helped design Giddings & Lewis' device,
has recently filed patents for a three-axis version of the hexapod that
is expected to be simpler and cheaper to build than the six-legged type.
Macro-scale Stewart platforms suffer from a "hot foot" ailment,
Fortune reported. "Heat from motors causes their struts
to stretch a bit when the machines are at work, which can affect the cutting
head's accuracy." Manufacturers are compensating mechanically for strut
expansion. Ralph Merkle has analyzed the positional uncertainty of the tip
of a simple molecular Stewart platform in the face of thermal noise, and
concluded that the Stewart platform performs very well in this respect.
Drexler discusses the design concept in Nanosystems.
In the world of entertainment, the nanotechnology meme spreads rapidly.
Electronic Gaming Monthly reported in April that Activision
has been filming action movie mega-star Bruce Willis (Die Hard, etc.) for
the lead role in a new interactive computer game called Apocalypse. "Willis
plays Trey, a nanotechnologist who recruits you in his battle against a
false prophet named the Reverend. Unfortunately, the Reverend is also a
wiz at nanotechnology, and he uses his skills to create the Four Horsemen
of the Apolcalypse...Plague, Death, War, and the Beast." Will the threat
of deliberate misuse/abuse of nanotechnology first reach general public
awareness through such paths? We'd prefer to think otherwise, but won't
be surprised if it does. After all, science fiction novels conditioned an
earlier generation to the ideas of space flight and nuclear energy.
Those interested in technical progress along the path toward nanotechnology
that leads through engineered proteins and designed polymers will find a
great deal of research of interest at the Web site of The Scripps Research
Institute. Only a few of the relevant research groups are featured here
(others can be accessed from the above home page).
The research group of Prof. Charles L. Brooks, III uses theoretical and computational methods to study protein folding and self-assembly. One current project made use of molecular dynamics to describe the thermodynamics of folding of a 48-residue protein fragment "based upon a first principles atomic level description of the protein and solvent environment." Another computational chemistry group with a substantial Web site on the molecular dynamics of protein and DNA molecules is the group of Prof. David A. Case. Highlights of their Web site include a summary of their research, and a gallery of structures of protein and DNA complexes determined in solution using NMR. Various software aids for very specialized aspects of molecular modeling can also be accessed from their welcome page.
The more experimentally focused research of M. Reza Ghadiri, who
will be one of the instructors at the Tutorial on Critical Enabling Technologies
for Nanotechnology this November, focuses on the design of artificial
proteins and catalysts. Of particular interest to nanotechnologists is the
beautifully illustrated page on nanotubes produced by the self-assembly
of cyclic peptides. The page explains key features of the cyclic peptides
that make self-assembly into a designed structure feasible, and how the
properties of the nanotube can be changed according to the design of the
cyclic peptide. Other research targeted towards the rational
design of artificial enzymes includes the use of the binding of metal ions
to peptides to control the folding of peptides into a three-helix bundle,
and the formation of a self-replicating molecular system in which
a helical peptide acts as a structural template to guide the assembly of
two constituent fragment peptides into the proper orientation to form the
original template peptide structure.
Lawrence Berkeley National Lab's Materials Sciences Division has made available on their Web site brief reports of research pointing toward nanotechnology. Some offerings from their Molecular Design Institute:
"Catalytic Atomic Force Microscopy", work from 1994 by P.G. Schultz and P. McEue that used a platinum-coated AFM tip to catalytically modify nanometer-scale patches of surface, converting azide group to amino groups. Their Web site contains an additional article on this research. [See also Jeffrey Soreff's report in Update 22.]
"First Nanotubes Made of Boron Nitride" reports work from 1995 by Alex Zettl, Marvin Cohen and Steven Louie resulting in the synthesis of nanotubes greater than 200 nm long and 6 to 8 nm outer diameter, composed of hexagonal arrays of boron and nitrogen atoms, much as carbon nanotubes are composed of hexagonal arrays of carbon atoms, but with more uniform structural and electronic properties than was the case with contemporaneous carbon nanotubes.
"Nanocrystal Structures Built on a DNA Scaffold" describes the 1996 work of Paul Alivisatos and Peter Schultz in using DNA base-pairing to position nanometer-scale gold particles with respect to each other. They hope to generalize this into a method of making larger, more complex three-dimensional structures to atomic precision. [See also Jeffrey Soreff's report in Update 27.]
Other relevant articles can be found in the Berkeley Lab archives by searching for key words such as "nanotechnology" or "protein folding".
Functioning nanomachine described on Web
This past June a team of Australian scientists unveiled a novel and exciting biosensor that has been billed as the world's first functioning nanomachine. It is not a nanomechanical device and not clearly on the road to molecular manufacturing, but rather an electronic device, an application of nanotechnology to a potentially huge biosensor market done by coupling biological molecular machinery and clever chemistry to electronic technology. A synthetic membrane adsorbed to a gold electrode controls the passage of an electric current via ion channels that open or close depending upon whether or not specific receptor molecules have bound their ligands, thus creating a very elegant and sensitive sensor for the ligand molecule. The accomplishment was described in a paper in Nature [see this issue's "Recent Progress" column], and also on several Web sites. A brief description of the device and how it works is available in a CSIRO media release, and in an article in the Sydney Morning Herald. A more technical description has been made available by the Cooperative Research Centre for Molecular Engineering and Technology at the University of Sydney. An easy to understand but very detailed and beautifully illustrated Web site on the project has been presented by the Australian Membrane and Biotechnology Research Institute. This site will satisfy both specialists and lay readers.
The Journal of the British Interplanetary Society (JBIS) has announced a special issue on "From Microsystems to Nanotechnology—Applications to Spaceflight". It is planned to cover micromechanics, microengineering, top-down and bottom-up (i.e. molecular) nanotechnologies, and the emerging micro-to-nano integration technologies, with a view to their applications to space science and technology.
The goals of the special issue are (1) putting together micro- and nanotechnologies to foster their integration toward new concepts of nanostructuring and new products, and (2) stimulating the applications of emerging micro-to-nano integrated components, devices, and systems to space applications.
Research and review papers submitted to this project should deal with the design, construction, and operation of micro- and nano-devices and systems, such as nanosensors and microactuators, MEMS, micro/nano integrated devices, molecular manufacturing, molecular electronics, nanocomputers, and nanosatellites.
Papers up to about 14,000 words can be accepted; the preferred size is 5,000-11,000 words. Authors receive 50 free offprints of their paper. Contributions are due by October 31, 1997, and are to be forwarded to: Dr. Salvatore Santoli, International Nanobiological Testbed, via A. Zotti 86, I-00121 Rome, Italy. Tel/fax +39.6.5613439, email intitsnt@uni.net. For instructions on manuscript preparation, contact JBIS directly at fax +44.171.820.1504.
