Biology aiding nanotech researchers

By SCOTT R. BURNELL, UPI Science News  |  Dec. 16, 2002 at 9:19 AM
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ARLINGTON, Va., Dec. 11 (UPI) -- The latest avenue in nanotechnology, the science of manipulating matter at the atomic or molecular scale, involves harnessing biological structures and processes, scientists said Wednesday at a conference.

The National Science Foundation sponsored the event at its headquarters to highlight ongoing nanotech research the agency is funding. The work occurs at the nanometer scale -- a nanometer is to an inch what an inch is to 400 miles.

One project, run by the University of Texas at Austin, looks to improve on natural nanoscale processes such as those that build seashells out of calcium carbonate, said Angela Belcher, a professor of chemistry and biochemistry at the university.

"We want to extend that to other parts of the periodic table," Belcher told the conference. "We want to evolve organisms to live with and work with other kinds of inorganic materials."

The project is working with viruses that can be engineered to stick to various elements, Belcher said. Experiments already have proven the process will work with germanium, cobalt, an iron-platinum compound and other materials, she said, adding the virus "glues" are even selective enough to tell the difference between different forms of iron oxide.

The viruses can grow in sheets, creating a flexible surface holding nanoparticles of various materials, Belcher said. This could lead to flexible computer displays, while removing the viruses after a nanostructure is formed could expand its usage into conditions where biological materials fail.

Crystallized proteins also hold great promise as nanostructure templates, said Vicki Colvin, director of Rice University's Center for Biological and Environmental Nanotechnology in Houston. At least 1,000 protein patterns are already known, more than what's available with polymers or other methods, she told the conference.

Many of the crystal structures have high percentages of water in them, an ideal setup for nanotech materials chemistry, Colvin said. Some of them are fragile, however, and would need a chemical "two by four" to do the job, she said.

"If we can stabilize these biomolecular lattices, we'll then have a much more robust system for the chemistries we want to do," Colvin said.

Once the crystals are formed, however, they can be remarkably stable, according to Colvin, even in the face of dehydration and temperatures reaching 120 degrees Celsius (248 degrees Fahrenheit). Experiments have shown some metals bind to the structures, then induce other elements to coalesce into wires and other useful objects, she said.

These developments are opening up a multitude of possibilities for nanotech researchers, said Barbara Baird, a professor of chemistry and chemical biology at Cornell University in Ithaca, N.Y., and director of the school's Nanobiotechnology Center. The biological approach lets scientists build from the bottom up, instead of whittling away at large pieces of matter, she told United Press International.

"These indications show it's already beginning to work at least as well as what we can do now, and maybe take us into areas we couldn't go before, taking advantage of nature's tools," Baird said.

Unlike science-fiction's "living nanobots," Baird said, viruses and proteins are not capable of reproducing in the inorganic structures being built. Scientists are aware of such concerns, she added, but today are still unable to "alter the biological structures successfully in the first place for this to happen."

Nanoscience also is interested in DNA, but not for the genetic data encoded in the double-helix structure, said Nadrian Seeman, a chemistry professor at New York University in New York City.

The molecule, only 2.5 nanometers wide, is being investigated more for the relative ease with which scientists can alter its chemical pattern for architectural tasks, Seeman told the conference.

The molecule is fairly rigid in lengths shorter than 50 nanometers, Seeman said, and multiple strands can be combined to increase its stiffness. Scientists can synthesize artificial, repeatable DNA sequences that will automatically assemble into geometric building blocks, he said.

Theoretical and experimental work has resulted in cubes and more complicated eight-sided structures, Seeman said. Researchers have also succeeded in engineering "markers" that protrude from the DNA structures to aid in measuring the final results, which could include creating nanoscale patterns to control deposition of inorganic material, he said.

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