Research roundup

13 August 2003

New technique could help speed nanotech commercialization
Engineers at Berkeley have found an innovative way to grow silicon nanowires and carbon nanotubes directly on microstructures in a room-temperature chamber, opening the doors to cheaper and faster commercialization of myriad nanotechnology-based devices.

The researchers were able to precisely localize the extreme heat necessary for nanowire and nanotube growth, protecting the sensitive microelectronics — which remained at room temperature — just a few micrometers away, or about one-tenth the diameter of a strand of human hair.

The new technique eliminates cumbersome middle steps in the manufacturing process of sensors that incorporate nanotubes or nanowires. Such devices would include early-stage disease detectors that could signal the presence of a single virus or an ultra-sensitive biochemical sensor triggered by mere molecules of a toxic agent.

Liwei Lin, associate professor of mechanical engineering, tested the new technique for processing nano-based microelectromechanical systems (MEMS) devices with his graduate students Ongi Englander and Dane Christensen.

The steps used in creating nanowires and nanotubes are essentially the same, though different chemicals and temperatures may be used. The Berkeley researchers, in this case, used a gold-palladium alloy with silane vapor to create silicon nanowires, and a nickel-iron alloy with acetylene vapor to create carbon nanotubes.

The researchers are continuing experiments to fine-tune the temperatures and length of heating time to create desired lengths of nanowires and nanotubes.
— Sarah Yang

Long-held theory of microbial diversity challenged
A new study led by Berkeley researchers has found genetic differences in a sampling of a species of hot-spring-loving microbes from around the world. The findings challenge the prevailing theory of microbial biodiversity, which holds that diversity for microbes is determined not by the extent to which populations are separated geographically, but by environmental factors.

To test this theory, Rachel Whitaker, a graduate student working with professor of plant and microbial biology John Taylor, trekked around the globe to collect samples of a microbe called Sulfolobus islandicus, which thrives in the extreme environments of geothermal hot springs and volcanic vents. Samples were collected from the Mutnovsky Volcano and the Uzon Caldera-Geyser Valley region on the Kamchatka Peninsula in eastern Russia, the Lassen Volcanic and Yellowstone national parks in North America, and the volcanic region of western Iceland.

In all, Whitaker and her colleagues analyzed the DNA of 78 separate cultures of Sulfolobus islandicus, finding small but significant levels of genetic differentiation among populations that live in different areas, despite the fact that they existed in similar ecological conditions.

Moreover, the study shows that genetic differences increased in direct correlation with geographic distance. “If this type of geographic pattern occurs in other microbes, it means the microbial world is even more diverse than we had previously predicted, which is astounding,” says Whitaker.
— Sarah Yang

NIH grant to fund new-generation NMR
The National Institutes of Health has awarded Berkeley nearly $6 million to purchase the most powerful magnet available for studying protein structure — and to push its limits in discovering the structure and dynamics of biomolecules.

The nuclear magnetic resonance (NMR) machine, with wire coils cooled by liquid helium to a few degrees above absolute zero, will put Berkeley researchers and other local scientists at the forefront of efforts to understand how proteins are put together and how they change shape as they do their job. Such understanding is essential if researchers are to tackle diseases and develop drugs to treat them.

The five-year, $5.9-million grant will be run by Berkeley researchers who are part of the California Institute for Quantitative Biomedical Research (QB3).

“One of the central themes in QB3 is using structural biology to understand how biological molecules — proteins, nucleic acids and carbohydrates — carry out their function,” says project leader David Wemmer, professor of chemistry and a faculty scientist at the Lawrence Berkeley National Lab-oratory. “This NMR system will allow us to push the envelope to see what we can learn about protein structures and the dynamics of structures and how they interact with other things.”

The several-ton instrument, a 900 Megahertz NMR that uses a powerful 21 Tesla magnetic field, will be housed in the basement of the campus’s major new research building, the Stanley Biosciences and Bioengineering Facility, begun this spring and scheduled for completion in 2006.
— Robert Sanders