Researchers create nanotubes that change colors, form 'nanocarpet' and kil...( de. Remarkably in addition to being ab...)

de. Remarkably, in addition to being able to kill cells, the resulting reaction mixture had the ability to self assemble into beautiful nanotubes of uniform structure. After searching for what was forming the tubes, the researchers discovered that synthesis of a secondary salt and diacetylene, thereby creating a lipid molecule, also resulted in production of absolutely pure self-assembling nanotubes, all having the same diameter (89 nanometers) and wall thickness (27 nanometers). By comparison, a human hair is about 1,000 times wider.

When dried from water and other solvents, and under magnification, these nanostructures look much like a heaping serving of Kraft macaroni or ziti pasta. Incredibly, when coaxed with simple processing, the tubes align into the more formal pattern of a nanocarpet. Just like any rug, a backing, also self-assembled from the same material, holds it all together. The nanocarpet measures about one micrometer in height, approximately the same height as the free-form nanotubes.

"This alignment of nanotubes in the absence of a template is an accomplishment that has eluded researchers," said Dr. Russell, who also is a professor of chemical and bioengineering at the University of Pittsburgh School of Engineering.

"To our knowledge, the remarkable self-assembly of this inexpensive and simple lipid is unprecedented and represents an important step toward rational design of bioactive nanostructures. In addition, because they form within hours under room-temperature conditions, the significant costs of synthesizing carbon nanotubes can be reduced," explained Sang Beom Lee, Ph.D., research assistant professor of bioengineering in the School of Engineering, who is listed as first author.

To test the nanostructure's potential as a biosensor and antimicrobial, the authors conducted studies using the water-based nanotubes. Normally a neutral color, when exposed to ultraviolet light the nanotubes changed to a permanent deep
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Contact: Lisa Rossi
RossiL@upmc.edu
412-647-3555
University of Pittsburgh Medical Center
24-Sep-2004

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