Researchers enlist DNA to bring carbon nanotubes' promise closer ...( A team of researchers from DuPont an...)

A team of researchers from DuPont and Lehigh University has reported a breakthrough in the quest to produce carbon nanotubes (CNTs) that are suitable for use in electronics, medicine and other applications.

In an article published in the July 9 issue of Nature, the group says it has developed a DNA-based method that sorts and separates specific types of CNTs from a mixture.

CNTs are long, narrow cylinders of graphite with a broad range of electronic, thermal and structural properties that vary according to the tubes' shape and structure. This versatility gives CNTs great promise in electronics, lasers, sensors and biomedicine, and as strengthening elements in composite materials.

Current methods of producing CNTs yield mixtures of tubes with different diameters and symmetry, or "chirality." Before the tubes can be used, however, they must be disentangled from a mixture and "purified" into separate species of CNTs of the same electronic type.

"A systematic method of purifying every single-chirality species of the same electronic type from a synthetic mixture of single-walled nanotubes is highly desirable," the DuPont-Lehigh group wrote in Nature, "but the task has proven to be insurmountable to date."

The Nature article is titled "DNA sequence motifs for structure-specific recognition and separation of carbon nanotubes." Its authors are Ming Zheng, Xiaomin Tu, Anand Jagota and Suresh Manohar. Zheng and Tu are scientists with DuPont Central Research and Development. Jagota is a professor of chemical engineering at Lehigh. Manohar is a graduate student in chemical engineering at Lehigh.

In 2003, a team of scientists from DuPont, MIT and the University of Illinois at Urbana-Champaign developed a new method of separating metallic CNTs from semiconducting CNTs using single-stranded DNA and anion-exchange chromatography. The scientists reported their discovery in Science. The team was led by Zh
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