The University of Washington Student Newspaper Friday, February 21, 1997

News

UW researchers imitate life with new science Science I Natural processes are being used as the blueprints for humanity to create new technologies and materials Kevin Hall Daily Staff

Nature is providing the lesson plan for a relatively new field of science at the UW.Biomimetics - literally, imitation and mimicry of life or of living things - is a new branch of science that lies at the interface of biology and the physical sciences.The study lends itself to collaboration among many different disciplines of science. For instance, one project may include researchers from genetics, biochemistry, engineering or biology, to name a few. It incorporates materials and techniques drawn from naturally made substances into man-made processes and materials. Scientists hope this blending may one day lead to stronger, more cost- and energy-efficient products that are ecologically sound.Dr. Mehmet Sarikaya, a UW associate professor of materials science and engineering, is one leading research expert in biomimetics. He has worked on different applications in bioengineering for about the past eight years. "Nature, for the last 500 million years, has been developing various different biological structures that are perfected. We want to learn from these and be able to design and process new technologies from them," Sarikaya said.One possible new technology Sarikaya has been exploring is an impact-resistant armor better structured than contemporary armors found on tanks and shields. The new armor is modeled after the ancient design of the abalone shell. Along with Ph.D. candidate Dan Frech, they have discovered the intricate micro-architecture that makes up the shell's mother-of-pearl appearance.Called nacre, it's composed of 98 percent calcium carbonate or chalk and 2 percent organic matter. The shell is twice as tough as the toughest of any ceramic material ever produced by man."Nacre is a structure usually found on the inner portions of the mollusk shells, in which the structure resembles brick-and-mortar organization," Sarikaya said.The layers of brick and mortar, which compose 98 percent of the shell, are composed of hexagonal-shaped "bricks" of aragonite crystal, with each compounded layer only one-thousandth of a millimeter thick. The "mortar" makes up the other 2 percent and is composed of polysaccharoids and proteins.What Sarikaya and Frech hope to find by studying the minute, intricate structure is how it forms in water and at room temperature, conditions nature uses to produce its minor miracles of the physical world."I don't think it's possible to make this kind of a structured ceramic composite material currently by industrial means," Frech said. "That's why we're studying the natural processes, to see how the formation takes place, and to see if we can utilize some of the principles to make our own materials which will be far superior by this kind of a mechanism to current structural ceramics," he added.The work done on the abalone shell is leading to interest from the paint, paper and composite materials industries. They are interested in possibly using the hexagonal shape of the crystals to revolutionize the current shape and size of the filler particle industry.No technique currently exists to produce hexagonal, platelet-shaped particulate materials. Researchers are trying to find the mechanisms behind the biomineralization of the abalone shell, or how it forms its individually shaped crystals. Another area of biomimetics that Sarikaya and others are looking at is a magnetic bacterium that exists in freshwater and saltwater swamps, lakes and other bodies of water.What makes the bacteria interesting is its ability to utilize a function called magnetotaxis, or navigation via the earth's magnetic fields. Other higher animals such as dolphins and bees are already known to use this capability.Small particles of iron oxide exist within highly organized segments of the bacteria that enable it to move about freely and locate food near the magnetized centers of the earth. A "magnetic moment" occurs within the bacteria telling it which way to move by its sensing the magnetism driving it.Sarikaya explained, "There is no technique currently that allows you to form these highly organized magnetic particles. This could lead the way to better suited magnetic storage disks in our computers."Deer antlers are also intriguing to the biomimeticist because they resemble bone, and may contain the information for humans to one day replicate them for use as bone replacement and regeneration.Sarikaya noted, "The deer shed their antlers every year and grow a new set of them annually. They grow fast, too - almost an inch a day during the summer months."By contrast, our bones grow very slowly and even quit growing after about 35 years of life. By studying bone and antler formation in deer, we could learn more about how we might be able to, in the future, grow bone that fast."Two other areas that Sarikaya raised as possibilities for future research are spider silk and deep-sea sponge spicules.Researchers already know that spider silk is an extremely strong material, comparable to steel cables. What they want to find is how to make a polymeric synthetic material that is of similar quality and strength to spider silk, and how to make it reusable and recyclable, like a spider does when it consumes its own webbing. "These biogenic materials, materials produced from organic matter and living creatures, are amazing examples of nature's power and prowess," Sarikaya said.Graduate student Nathan Kohler was intrigued by Atlantic sponges and the tiny strand-like fibers or spicules that protrude outward from the creature.The spicules are used by the sponge to trap and collect sunlight and transfer the light to the inside of the sponge where green algae exist to produce food for the creature."The spicule is acting like an optical fiber here," Sarikaya stated. "[Kohler] has begun research to find out whether these silicon spicules are better than current optical fibers and how they are made by the sponge. If they are better, than the next step is to figure out how," he added.Sarikaya not only hopes to help with developing new inorganic materials, but to one day see revolutionary scientific processes such as genetically engineered materials come about."You manipulate an organism's genetics to produce a material like soft tissue, muscle or maybe spider's silk. You do that by genetically altering the organism's cells that affect the growth of these and other materials," he explained.Sarikaya said his research was assisted with the expertise of Dr. Richard Humbert, a bacterial geneticist, and professors Clement Furlong, a medical geneticist, and James Staley, a microbiologist.Current challenges facing biomimetics scientists include how these biogenic materials, materials created by living creatures, are created at room temperature and also how they are made in water. Most man-made materials are produced under extreme conditions of high temperature and pressure."These are major questions that need to be answered," Sarikaya said.Materials sciences are located in Roberts and Wilcox Halls.

Copyright © 1997 The Daily of the University of Washington

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