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Linda Griffith: Growing Model Bodies

Angela Belcher: Harnessing Viral Power

Ram Sasisekharan: Complex Sugars Complicate Biology

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Angela Belcher: Harnessing Viral Power

Letting Nature Do the Work

Millions of molecular machines exist in nature. Magnetotatic bacterium in the ocean make small, single domain magnets, which are used for navigation. Abalone shells secrete proteins and ions to create strong shells made from calcium carbonate or chalk. Both are genetically controlled and produced at ocean temperatures from non-toxic materials.

What if scientists used the successful processes nature has developed through natural selection to create new materials, such as energy sources? Angela Belcher, associate professor of materials science and engineering and biological engineering, wants to know. Her vision is a symbiotic harmony between nature and laboratory.

"We're all working together to see if we can understand how nature makes materials and convinces organisms to work with materials that they haven't already worked with before," she says. "We're going to force organisms to live with semiconductor materials and ... electronic materials so that they can start to use them and process them."

Growing Energy Sources

Belcher hopes to grow nanomaterials, that, among other qualities, self-assemble, self-correct, generate little waste, grow at room temperature and pressure, grow and recycle their own template, grow to a desired length and diameter and stop, span multiple length scales (from nano- to macro-levels), and are inexpensive. Sounds ambitious, but biology, as Belcher points out, has already figured out how to master many of these properties.

"My dream is to have a material that's genetically controllable and genetically tunable. I'd like to have a DNA sequence that codes for the production of any kind of material you want," she says. "You want a solar cell, here's the DNA sequence for it. You want a battery, here's the DNA sequence for it." Her lab has already produced the first virus-assembled nanoelectrode and virus-assembled battery, created in collaboration with professors Paula Hammond and Yet-Ming Chiang. The battery reached the theoretical capacity for energy density with the material they created and, by putting it on a flexible surface, Belcher weaves these into soldiers' uniforms to try to lighten their loads. Now, her lab seeks to develop a virus-based transistor.

Viruses and Yeast Provide Raw Materials

Belcher bombards a semiconductor wafer with non-toxic viruses to see which react, looking for one with the chemical functionality matching the material. Once found, the virus is inserted into a bacterial host, which replicates millions of copies. The viruses act as a scaffold and are coded to grow semiconductor particles along their length. The results are breakthrough alternative energy sources. Viruses can also form liquid crystals for LCDs and possibly be used in laser technology, solar cells, and magnetic storage. Belcher's lab has also spun virus fibers, much like a spider spins a web, to create optical fibers and biodetectors.

Yeast can also create semiconductor materials. One of Belcher's graduate students, Asher Sinensky, is developing a yeast-based spray that finds defects in semiconductors, optically revealing defects with a fluorescent signal. One possible application is to find instrumentation flaws in the field, perhaps by spraying an airplane wing pre-flight to detect potential safety hazards. The researchers use the same yeast found in beer and bread, a cheap, scaleable material. "Instead of Budweiser, we think of it as Nanoweiser," Belcher says.

...go on to Part III: Ram Sasisekharan: Complex Sugars Complicate Biology