The University of Arizona Alumnus / Spring 2008
PUTTING PEOPLE FIRST: Making Endowed Chairs a Priority
Linda PowersCollege of Engineering
Thomas R. Brown
Endowed Chair for Bioengineering
Life in the Fast Lane
by Ford Burkhart
Photos by Jacob Chinn
make many tests at once. “Just imagine: we can test everything en masse.”
On a battlefield, an instant blood test for HIV and hepatitis could hasten a direct transfusion and save a soldier’s life. A University of Arizona professor has designed just such a test.
And a better device to test for signs of life in an extreme environment like outer space would help NASA search for extraterrestrial life. She’s made one of those too.
All in a day’s work for Linda Powers, who holds the UA’s Thomas R. Brown Chair for Bioengineering. Beyond those stunning accomplishments are even more challenges that fuel her efforts to expand the horizons of medical diagnostics. Her tools may help the world cope with the emerging threats from SARS, bird flu, and anthrax — threats that will require super-fast tests for hazardous microbes or pathogens.
One day, the devices that spin off from her research may protect airport and border checkpoints, enhance the work of pharmaceutical companies, and speed the tests of water quality around the world.
This work is unfolding on the frontiers where biology, medicine, and engineering converge. Powers’ intricate techniques capture molecules — those belonging to pathogens or other biochemicals — and then use them in a broad range of nanoscience devices to instantly rule in, or out, the presence of similar molecules.
The military applications of her work are clearly the most compelling.
“Imagine a soldier is dying, and a buddy says, ‘Take my blood and save my buddy,’” Powers says. With her blood test, “Now, you can make that decision within minutes. That’s just one example of why we are so interested in using this technology.”
With the old blood tests, it can take 24 to 48 hours or longer to get results, especially if separate tests are done for the 15 or 20 common blood-borne threats like HIV or hepatitis B.
“There are some microbes that are not pathogenic, some that are. Checking on all the possibilities can require a battery of different tests,” Powers says. “It would be cumbersome outside a lab, a huge screening process.”
What seems to excite her most is the chance to make many tests at once. “Just imagine: we can test everything en masse,” she says, spelling out one of her favorite French terms, meaning “in a group.”
Powers’ enthusiasm is catching, and she regards outreach as one of the main responsibilities of her endowed chair. “You have to take a leadership role,” she says. “I try to use my position to help guide young people, both students and faculty, to become successful.”
She works with other faculty women in engineering to mentor them through the minefields of a university or corporation. “Women have many challenges in common — running a family, responsibilities for children, dealing with male peers. I believe we can help each other.”
She also works through a group called Women in Science and Engineering, or WISE — and yes, some men do attend, she adds — setting up coffee-house chats with faculty experts to discuss global problems that will shape the future.
“I want students to ask themselves, ‘What can I do as a scientist or engineer that will affect our global problems?’ If you combine your talents and interests, your job is exciting and you make contributions that you may not anticipate. Maybe the student will combine engineering with a love of scuba diving in a search for alternate fuels.”
Or they might, as does Powers, combine science and engineering with exploration of extreme environments in a search for life forms.
Powers, who has appointments in both the Department of Molecular Biophysics and the Department of Electrical and Computer Engineering, organizes branches of her research at three major labs scattered around the campus. One is in BIO5’s Thomas W. Keating Bioresearch Building.
“The UA,” she says, “is perfect for interdisciplinary work. There are no ‘glass’ walls like you might find at so many places.”
A Harvard Ph.D. in biophysics, Powers has helped scientists start small businesses. Her own venture, MicroBioSystems, now based in Utah, will soon make Tucson its home.
She says her company’s mission reflects some parallels with the spirit of Thomas R. Brown, the entrepreneur whose family endowed her chair. The firm tailors technology for specific uses and acts as a go-between for academics and the business world.
“Undertaking the development of a business is daunting. Fortunately, the UA has an incubator which provides much-needed help. But there are always problems with a new high-tech business and it is difficult to bridge the gap between industry and universities. It’s not so simple to work within a university.”
In fact, she’s an artist at making the complex seem doable.
Her world of high-tech sensors is, in a way, an extension of a very simple notion by coal miners who took a canary into a mine. If the canary samples the air and dies, there’s an invisible peril, methane gas, and it’s best for the miners to respond, fast.
In Powers’ sensors, the canary is replaced by a sampling system with an ingenious way of sampling an environment for pathogens.
To survive in human bodies, pathogens must be smart. They need minerals and can’t just go shopping for atoms of iron. So they find them in the pantry of their host, namely us. Our bodies have iron, but it is carefully hidden, because free iron is toxic. The wily pathogen knows exactly where to look: inside the body’s iron-packaging device, a molecule called a heme (pronounced “heem”). In a heme, the iron atom can be safely stored. The hungry microbe will grab the whole heme and use the iron atom as food.
Knowing these habits of the pathogen, Powers’ team sets a trap. It captures a pathogen in the blood, urine, or spit, in any context, with a clever kind of sensor. The heme becomes the trap, dangled on the end of a nanotether where a passing microbe in a drop of blood would bump into it and bond with it. Wash off the blood and you have captured a pathogenic microbe.
The principle applies not just to blood tests but to testing a sample of soil, rock, or ice in a Mars-like extreme
environment. Working with the NASA Spaceward Bound program, Powers has already gleaned important information, and her tests may someday be adopted for a future Mars mission.
Powers has performed her surrogate outer-space tests in the Mohave Desert in the American Southwest and in Chile’s Atacama Desert, the driest place on earth. Her team takes portable field units equipped with instruments — filled with engineering marvels like optics, algorithms, and control systems — to sample rocks and soil to determine if there is “something living” there.
The first test involves shining light on the surface and analyzing the light that comes back, a test that can distinguish live or dead cells and spores, a dormant form of microbes. If that test is positive, then in a second test researchers wipe a surface on top of a rock, then shine a certain light on it to indicate whether it has captured microbes suggestive of life. The Atacama Desert supports very little life as we know it, she says, but the Mohave Desert has significant levels.
Powers has pushed ahead with NASA’s Jet Propulsion Laboratory on instruments that also will distinguish the chemical composition of rocks.
Another application is in water quality. For example, if you built a new house and needed to drill a well, the state would take a sample of the water and test it. Up to 48 hours later you’d get the results. The delay is itself a cost. And the old tests don’t cover every possible pathogen.
“With our method,” she says, “the cost is pennies and the answers are nearly instantaneous — within minutes.”
One significant medical application is to determine diseased tissue in the eye, for conditions like glaucoma, cataracts, and various kinds of infections.
Her lab is already tackling some of these problems.
Over the horizon are more dreams, Powers declares. “I would like to develop, test, and deploy a cheap diagnostic for HIV, TB, and malaria, for field use in Third-World countries,” she says, “and just for pennies.”
And while she’s at it, she’d like to achieve one more landmark: “Finding clear evidence that extraterrestrial life exists, or has existed, using our technology.”
An endowed chair has to aim high.
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