Aug. 14, 1998 Technique Could Be Used Some Day For Inexpensive, Rapid Manufacture Of Molecule-Sized Computer Technology -- NYU Chemist Nadrian C. Seeman and Colleagues Report Findings In August 6th Issue Of Nature
A team of researchers led by New York University chemist Nadrian C. Seeman, in collaboration with California Institute of Technology computer scientist Erik Winfree, has developed a simple, predictable and highly precise process for causing molecules in solution to assemble themselves into two-dimensional crystals with pre-programmed topographic features. Such molecular self-assembly presents a 'bottom-up' approach to the fabrication of objects specified with nanometer precision.
The work of Seeman's team, which is reported in the August 6th issue of Nature, is regarded as a significant advance in nanotechnology -- scientists' efforts to control the detailed structure of matter on the finest possible scale. For decades, scientists have struggled to develop reliable techniques for arranging groups of molecules into orderly structures.
The research of Seeman's team may have practical implications for engineers attempting to develop molecule-sized computer technology. The work may also lead to advances in the determination of the structures of biological molecules.
Seeman's team worked with synthetic DNA double-crossover (DX) molecules. The researchers exploited the key chemical feature of DNA -- its ability to associate with and recognize other DNA molecules by sequence-specific base-pairing. Genetic engineers make use of this feature by constructing DNA with single-strand overhangs or "sticky ends" able to bond to complementary base sequences and bring two DNA molecules into proximity.
Visualized with atomic force microscopy, the crystals fabricated by Seeman's team were found to conform with their intended design. One set of crystals had an A-B repeating structure of DX molecular units, where the B units possessed modifications visible as stripes. The other set had an A-B-C-D structure, where only the D units possessed the modifications. Both sets had evenly-spaced stripes at predicted separations; the stripes in the A-B-C-D structure were twice as far apart as in the A-B structure, demonstrating the accuracy of the molecular recognition.
The authors of the Nature article, entitled "Design and self-assembly of two-dimensional DNA crystals" are as follows: Erik Winfree, Computation and Neural Systems, California Institute of Technology; Furong Liu, NYU Department of Chemistry; Lisa A. Wenzler, NYU Department of Chemistry; and Nadrian C. Seeman, NYU Department of Chemistry.
Nadrian C. Seeman was born in Chicago in 1945. Following a BS in biochemistry from the University of Chicago, he received his Ph.D. in biological crystallography from the University of Pittsburgh in 1970. His postdoctoral training, at Columbia and MIT, emphasized nucleic acid crystallography. He obtained his first independent position at SUNY/Albany, where his frustrations with the macromolecular crystallization experiment led him one day to the campus pub. There, he realized that the similarity between 6-arm DNA branched junctions and the periodic array of flying fish in Escher's 'Depth' might lead to the rational approach to crystallization described here. He has been trying to implement it ever since, for the last ten years at NYU. Further information is available at http://seemanlab4.chem.nyu.edu.
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