Taking lessons from nature

Weeds: By studying the pollination of plants, researchers hope to develop a super-glue to be used in the assembly of machine parts.

October 08, 2001|By Jon Van | Jon Van,SPECIAL TO THE SUN

The next generation of super-fast computers might be developed by scientists studying the sex life of a weed.

At the University of Chicago, scientists are developing a new type of super-small, super-strong glue that might prove a powerful aid to a wide array of new technology. A team of botanists, physicists and chemists is working on this new class of adhesion agents that can bond very tiny components in a way that could lead to self-assembly of tiny machine parts.

The project illustrates the new direction research is taking, where scientists look to nature for the latest technologic breakthroughs. And "teamwork' is the watchword.

Breaking down the boundaries that have long marked different fields of science is so vital to modern research that the University of Chicago's new $180 million research center, which soon will begin construction, is designed to encourage team science.

Like many discoveries, the super-glue project began with curious people asking the sort of straightforward questions that 6-year-olds often concoct to baffle their parents - how do plants mate with their own species?

The answer: With all the pollen that blows through the air and is moved around by insects, it is common for pollen grains from a dozen species to land on a plant's female receptors. But only the pollen from the same species will stick and fertilize, while the foreign pollen will fall off.

A few years ago a team of plant biologists led by Daphne Preuss set out to learn how this works.

"We wondered what happened when the wind blows and insects walk around," said Preuss, an assistant professor of molecular genetics and cell biology. "We demonstrated that the wrong stuff rubs off easily, while the right stuff sticks tight, and we wanted to measure it."

Preuss discussed her quandary with David Grier, a physicist, who recruited one of his students to look at the problem.

"We have a tradition here of being interested in ordinary things: like why does coffee leave a ring when it forms a stain, and why does paper crumple?" Grier said. "So Daphne's problem was very appealing intellectually."

Looking at a weed related to the mustard plant Arabidopsis thaliana, the Chicago team put pollen and unpollinated pistils together and pulled them apart, using apparatus of their own design and measuring the forces required. The scientists washed and buffed and generally massaged the pollen and pistils in various ways to determine how the cells were able to stick together with such strong adhesion.

"If these surfaces were just sticky, they'd attract all sorts of filth," Grier said. "The surfaces aren't sticky. They're waxy and inhospitable for adhesives - except for pollen grains of the same species. Mustard sticks to mustard, but petunia doesn't."

The scientists concluded that molecules on the surface of the pistil grab onto molecules on the surface of the pollen to form a strong bond. The molecules involved are unlike any that scientists have studied. Milan Mrksich, an associate professor in the department of chemistry, joined the team and is screening experiments to identify the molecules at work.

"We chemists are constantly learning from biology," said Mrksich. "Here we can learn how to cold-weld parts together."

The scientists expect that once they find the lock-and-key combination for the Arabidopsis plant, they'll be able to find similar molecules used by other plants to do the same job of uniting pollen and pistil. Nature must have designed unique binding agents for every different plant species, the scientists expect.

"If these glues are very specific and there are many, many pairs of them, it should be possible to use them to create microstructures," Mrksich said. "Little machines could self-assemble if you equip the components with the right molecules that will bond together."

Grier said he hopes to use this idea to fabricate optical switches that could be used in a new generation of photonic computers . Mrksich envisions using the glue to build different classes of bio-chips.

Cooperation among scientists from different fields is essential to modern research for several reasons, said Robert Zimmer, the University of Chicago's research vice president.

Technology advances have given scientists in most realms the opportunity to study things on a very small scale - in nanometers or billionths of a meter. At that scale, many biologic phenomena can be understood as complex problems in physics or chemistry, he said.

Scientists also have computers that enable them to analyze vast amounts of data and delve into a level of complexity once out of reach.

"The nano-scale issue, the complexity issue and the computational issue are three generic developments allowing whole new sets of interactions among chemistry, physics and biology," Zimmer said.

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