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(Reprinted from Foresight Update 27:5.
Foresight Update is a publication of the Foresight
Institute. ? 1997 by the Foresight Institute. Reprinted by permission.)
(Issue 2; posted February 20, 1997; archived March 6)
The International Business Communications conference on "Biological Approaches and Novel Applications for Molecular Nanotechnology" was held December 9-10, 1996, in San Diego, Calif. The conference, attended by about 120 researchers and business leaders, focused on the areas of nanosystems technology outlined in welcoming remarks by conference chairperson Allen J. Bard of the University of Texas at Austin: (1) fabrication, (2) characterization, (3) connections to the outside world, and (4) near term applications, particularly in the areas of sensors, electronic devices, and photodevices.
Within these clearly defined areas of focus, 20 speakers and 6 poster presenters covered a wide array of technological approaches. This article summarizes briefly a portion of the interesting work presented.
The results presented at this conference were for the most part focused on near term applications of nanometer scale technologies, rather than upon the complex molecular machinery and general molecular manufacturing capabilities that will come later, and which are the focus of Foresight Institute's efforts. Nevertheless, the excellent work presented is well worth our attention. Some of these research efforts offer potential direct paths to the construction of complex molecular machinery; others would appear to contribute to the long term goals only indirectly via the development of infrastructure and the success of industries committed to developing molecular scale technologies. It is also worth considering that the rapid and varied development of these technologies brings the possibility that capabilities useful for the development of molecular manufacturing may come from unexpected directions.
The Monday morning session was largely devoted to scanning probe microscopy. Dr. Bard described his work with scanning probe electrochemical (SECM) methods for fabrication and characterization of nanostructures. Although SECM is not capable of atomic scale resolution, applications to the fabrication of micrometer and sub-micrometer scale structures by electrochemical deposition and etching were presented. John T. Thornton of Digital Instruments presented a wide range of applications of tools made by his company to the study of biological samples. This includes using mechanical force to induce conformational changes in certain proteins such as bacteriorhodopsin. Dr. Kong Gay Loh of TopoMetrix Corporation presented the use of his company's tools for novel applications, including thermal conductivity characterization of polymers and near field optical microscopy of individual fluorescent molecules.
Prof. William A. Goddard III of the California Institute of Technology addressed the use of atomistic molecular dynamic simulations to understand and design nanosystems. He excited the audience by predicting that the protein fold prediction problem for sequences up to 50 amino acid residues (such a polypeptide would have 1,023 possible configurations) would be solved within the coming year, either by a hierarchical folding strategy he described or by similar efforts of others.
The topic for the afternoon session was programmable self-assembly systems. Dr. Devens Gust of Arizona State University described his work with complex organic molecules that mimic photosynthetic electron transfer, and how these can be used to design molecular optoelectronic switches. Ned Seeman of New York University presented his recent work on the construction of nanoscale topological structures using designed DNA molecules. He described progress toward making the angles in such constructions less floppy by incorporating double crossover DNA molecules in triangles constructed of DNA.
Dr. Michael Heller of Nanotronics, Inc., and Nanogen, Inc., and his collaborator Prof. Sadik Esener of UC San Diego gave two presentations of the very elegant work of their groups in using DNA to make micrometer-scale patterns on silicon surfaces, and their designs to use DNA to control the assembly of molecular electronic and photonic nanostructured materials. Among the most visually impressive demonstrations presented at the conference were videos of their technique of electric field-assisted assembly of DNA structures. Fluorescence-tagged DNA oligonucleotides in solution were made to hybridize to specific regions of a silicon chip containing complementary DNA oligonucleotides orders of magnitude faster than they otherwise would by imposing an electrical bias on that specific region of the chip. By manipulating where the bias was applied, DNA molecules could be made to desert their complementary partners on one section of the chip and to bind to another such section in several seconds.
Professor Donald E. Bergstrom of Purdue University presented a wide range of options to modify the characteristics of DNA by incorporating novel bases synthesized via organic chemistry, and by modifying the nucleic acid backbone. Even more interesting were his methods to attach DNA molecules to rigid small organic molecules so that DNA complementarity can be used to guide the assembly of small molecules into various larger nanoscale structures. Dr. Roger Cubicciotti of Biotechnology Development Associates expanded upon the theme of DNA directing the formation of larger structures by proposing the use of specially evolved DNA sequences to form molecular switches and other molecular devices by binding each of two specific functional molecules, such as a donor and its associated receptor molecule, and then positioning these two molecules with respect to each other to elicit the desired function.
The second day of the conference was more heavily focused on micromachinery-based approaches and applications. Dr. Gregory T.A. Kovacs of Stanford University presented an excellent and entertaining overview of methods in micromachining, and Dr. Thomas G. Thundat of Oak Ridge National Laboratory described a wide range of applications of micromachined sensors. Dr. Thomas Neumann of the University of Washington and Dr. Gil U. Lee of Naval Research Laboratory each discussed different applications of micromachined devices to measuring the forces exerted by specific individual molecules. Dr. Dennis M. Newns of IBM proposed a field effect transistor based upon the Mott transition in a molecular layer. Dr. Harry Stylli of Aurora Biosciences Corporation presented a miniaturized system for high throughput screening for use in drug discovery. Dr. Nir Kossovsky of Heisenberg Principles, Inc., described their "aquasome" technology for preventing biomolecules adsorbed to ceramic particles from denaturing.
The last three talks focused on molecular electronics and photonics. Dr. David Beratan of the University of Pittsburgh described theoretical studies of tunneling of electrons through DNA and proteins. Prof. Robert R. Birge and Jack Tallent, both of Syracuse University, described the rich applications of bacteriorhodopsin, both the natural molecule and several specially designed mutations, to holography and to three-dimensional optical associative memory devices.
Jim Lewis constructs and maintains the Web sites of the Foresight Institute and the Institute for Molecular Manufacturing. He has coedited two books on nanotechnology.
Endlinks
MIT's Technology Review - Ralph Merkle introduces and predicts advances in molecular technology. A more technical version of the article is also provided.
Advances in Anti-Aging Medicine - Ralph Merkle discusses some possible medical applications of nanotechnology.
Foresight Update - Gregory Fahy on biological molecular nanotechnology.
DNA Nanotechnology in Ned Seeman's Laboratory - Nanotechnological applications of DNA.
Usenet newsgroup - sci.nanotech.
