Biomimetics Research

Following In Nature's Footsteps

By Eric Wagner

Engineers have long used the natural world as inspiration for new materials and structures. In the past twenty years or so, however, their methods for understanding and tools for imitation have become much more sophisticated.

The field is formally known as biomimetics, and Mehmet Sarikaya, a professor of materials science and engineering at the University of Washington, has been at the forefront of the field for two decades.

Now, Sarikaya is the director of a recently established Genetically Engineered Materials Science and Engineering Center (GEMSEC) at the University of Washington (UW) in Seattle. Funding for the center comes from the National Science Foundation as part of its Materials Research Science and Engineering Centers program (NSF-MRSEC; www.mrsec.org). The NSF-MRSEC grant, with matching funds, totals $7.7 million over six years, and can be renewed every six years.

Natural processes have produced materials that have remarkable characteristics. For instance, consider an abalone shell. "It is basically chalk, but the abalone's nacre, or mother-of-pearl, structure has the highest toughness of any ceramic material. You could drive a truck over it and it wouldn't break,” says Sarikaya.

So what is even more amazing in the eye of the engineer is that Nature assembles natural materials at room temperature. And at atmospheric pressure. And in water, no less. "Based on biomimetics,” he says, "we want to do the same thing with proteins."

At the UW, GEMSEC is an interdisciplinary enterprise with ten principal investigators from materials science and engineering, chemical engineering, chemistry, electrical engineering, and microbiology. The center will support research and education that integrates molecular biology with the state-of-the-art nanotechnology to construct materials unachievable through traditional biological or chemical methods alone. The materials, with novel photonic, electronic, or chemical properties, will have potential applications in both practical engineering and medicine.

The center will also establish an international network of laboratories that share common interests in molecular biomimetics and partner with industry and national labs.

The new directions for the center's research are the simple lessons of biology. "We control genetics to produce proteins, but evolve them so they'll work better,” Sarikaya says. "We want to follow Mother Nature's molecular footsteps."

For Sarikaya and colleagues at GEMSEC, proteins are the key. Some proteins ferry material from one part of the cell to another, while others form muscle, hair, or collagen. And some proteins, called DNA binding proteins, continue the cycle of controlling the genes in making more proteins.

Scientists know there are approximately 60,000 proteins in the human body. Sarikaya looks at this exquisitely complicated system and sees engineering possibilities. "We know that Mother Nature is producing all the soft and hard tissues, and uses proteins to accomplish that. So they're extremely versatile things. Our interest is, what else can we have them do for us?”

Their exploration of proteins' potential focuses on three premises. First, that given proteins can be built to molecularly recognize certain materials, such as metals, ceramics, and semiconductors. "We know this is true from viruses,” he says. Proteins attached to the outside of a virus guide it to its cell targets. "So proteins are good at finding their way,” he says. We want proteins to do the same thing with nanomaterials, to synthesize and guide them to form useful structures.

The second premise is self-assembly. This is a common trait not only of proteins, but also of other macromolecules. "If you put the proper components into a stew in the right concentrations,” Sarikaya says, "you will get what you need through self-assembly.”

The third step is where the GEMSEC research will be most important significantly add to the growing pool of molecular tools: "Once the first two are done,” Sarikaya says, "we can change the molecular recognition of the protein, tailor its function by carefully genetically engineering them.”

Sarikaya is excited about the potential uses in nanofabrication, for example, the assembly of very small integrated circuits. Using proteins as tethering molecules to carry nanoparticles, the circuits will essentially self-assemble, or probes made as such will light up as they find their cancerous targets. Already, tethering proteins have been attached to nanoparticles that assemble without direct human manipulation.

Eric Wagner is a graduate student in biology at the University of Washington.

Images:

Top: A scanning electron micrograph image of the growth edge of red abalone shell. The nacre, or mother-of-pearl material of the shell is one of the toughest and strongest material known.

Middle: Dr. Mehmet Sarikaya is Professor of Materials Science and Engineering at the University of Washington, and the director of the Genetically Engineered Materials Science and Engineering Center.

Bottom: Molecular dynamics model of a quartz (crystalline silica glass) binding peptide (genetically engineered at GEMSEC) attached to PIII coat protein of M13 Phage displayed on the surface of quartz crystal in water.

All images courtesy of Mehmet Sarikaya.