Biocomposite Research at UT:
Nature's Way of Making Technology
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A research team from The University of Texas at Austin is engaged in pioneering research that involves binding living materials -- proteins from bacteria, viruses, and DNA strands -- to inorganic materials such as semiconductor and metal particles. These hybrid materials, called electronic biocomposite materials, might be used in building nanoscale electronic devices. The UT scientists are paving the way for development of a host of technological marvels -- potential building blocks for transistors, wires, connectors, sensors, and computer chips far smaller than anything manufactured so far. Biocomposite materials exist in nature in the form of such substances as shell and bone. By studying and copying the processes that nature uses to create these inorganic materials, the scientists are creating new materials to build electronic components. 
"Nature has amazing control over forming materials like shells and bones, but never 'moved on' to electronically important materials like semiconductors," says Dr. Angela M. Belcher of UT Austin's Department of Chemistry and Biochemistry and the Texas Materials Institute. Belcher, the lead author of a research paper on the subject in Nature magazine (June 2000) and the leader of the UT team, explains that "in my group, we focus where nature left off. We are learning from nature, learning how nature makes materials and applying this to other systems." These new biocomposite materials could result in smaller computer chips and other electronic components that are faster and cheaper. Experts have been predicting that the electronic industry is reaching the limits of miniaturization, which is why the field of nanotechnology has been declared a national research priority by the federal government. Nanos is the Greek word for "dwarf," and nanotechnology refers to the construction of highly miniaturized devices. 
Angela Belcher's Biomolecular Materials Group includes graduate students, undergraduates, postdoctoral fellows, and a host of collaborators from her department, from physics and engineering at UT, and fellow scientists from New York University and the University of California at Santa Barbara. Belcher has been featured in a Forbes magazine cover story (July 2001) and in newspapers across the country. In the fall 2000, she traveled to the White House to accept the Presidential Early Career Award for Scientists and Engineers, the highest honor bestowed on this group by the U.S. government. Belcher and graduate student Sandra Whaley have been isolating viruses containing proteins that can recognize and combine with gallium arsenide, silicon, indium phosphides, and zinc selenide. Their team has identified proteins at the ends of viruses that can differentiate between similar semiconductor alloys and bind to the ones the scientists prefer. "We are the only group using this approach," says Belcher. When the living proteins bind to the inorganic particles chosen by the scientists, the proteins in the viruses will automatically assemble the particles into desired patterns. In effect, the living organisms "grow" uniform components. Belcher draws a rough comparison to a car putting itself together on an assembly line, although she points out that the assembly line process is primitive in comparison with the precision that the viruses can achieve. "A lot of organisms can make materials better than we can manufacture them," she says. Belcher believes that any commercialization of products resulting from this research will be some years away. The next research step will be working with the materials to try to integrate them into electronic devices. This new field of biocomposites appears to overturn some of the basic concepts most people understand about a natural world divided into animals, vegetables, and minerals. Actually, the dividing lines between what is considered biological and what is considered mineral have always been fuzzier than is commonly assumed. 
"Biocomposite materials have been in existence for millions of years. We, ourselves, are biocomposite materials," says Belcher. All mammals produce tough, flexible bone and cartilage. Marine invertebrates surround themselves with protective shells. Whales have mouths full of baleen, which strongly resembles plastic and was once used for "whalebone" corsets. Human bodies contain bones, teeth, fingernails, and hair that are biocomposites. Biocomposites also have mechanisms in place to self-correct. "If something happens to one of our bones, a lot of times we can fill it in and correct it," says Belcher. "If we have a problem with our DNA, we have mechanisms to correct it." Angela Belcher graduated from the University of California-Santa Barbara (UCSB) in 1991 with a degree in creative studies, emphasizing biochemistry and molecular biology. She earned her Ph.D. in chemistry doing interdisciplinary research on organic and inorganic interfaces (connections) and biomaterials. Belcher switched to postdoctoral research in UCSB's department of electrical and computer engineering and the Center for Quantized Electronic Structures. She did her Ph.D. work on seashells, finding that a shell, which is 98 percent inorganic and 2 percent protein, is an excellent example of the link between inorganic and biological materials. Realizing that mollusks have "perfect control" over the growth patterns of their shells, she thought: "Wouldn't it be great to have that kind of control over the kinds of materials that nature hasn't worked with?" Belcher says, "If you look at the periodic table, you'll see that natural biological minerals are made out of calcium, barium, iron, silica, and phosphates -- that's it. So there's this whole other part of the periodic table that biology doesn't use to make materials. We are trying to genetically engineer proteins to be able to make structures out of everything else." She says her group is, in effect, "doing evolution" in their lab. They are evolving proteins to interact with materials that have important electronic properties and magnetic structures. 
Trying different virus and semiconductor combinations, the researchers went through 100 million viruses before identifying the ones that worked best with the desired materials. Only proteins that bound themselves tightly to the semiconductor survived the experiment and were cloned by her group. "Viruses were chosen by whatever material they naturally 'stuck' to the best and, consequently, only tend to 'stick' to that particular material," Belcher explains. Still, she says, the process was something akin to having scientists round up 100 million people, all with different house keys, and trying to get them to unlock the same door until the right key was found. "We used evolutionary tools to select proteins that can control these technologically important materials, with the goal of building next-generation devices," she says. Angela Belcher's work cuts across the three fields of inorganic and materials chemistry, molecular biology, and electrical engineering. "We are a multi-disciplinary lab. We do it all," she says. "This project would not have worked without the ability to use all three approaches. I would not have been able to come up with this idea had I not studied in all these fields." The work of the UT Austin research team was supported by a DuPont Young Investigator Award presented to Belcher; a grant from the Army Research Office and Defense Advanced Research Projects Agency; the National Science Foundation; the Robert A. Welch Foundation; and faculty start-up funds provided by the University. The research is taking place primarily at UT's Department of Chemistry and Biochemistry and the Texas Materials Institute. In addition to receiving the prestigious Early Career Award for Scientists and Engineers, Angela Belcher has been honored with the 2000 Beckman Young Investigator Award, the 2000 IBM Faculty Partnership Award, the 1999 DuPont Young Investigator Award, the 1999 Army Research Office Young Investigators Award, the 1997 Outstanding Graduate Student Award in Chemistry given by the University of California, and the 1996 Outstanding Chemistry Graduate Student Award given by the American Institute of Chemists. By Mary Lenz, from Focus on Science magazine (summer 2000)
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