UI researcher: Cells could be super sensors

Study focuses on detecting toxins – and giving warning

Don Cropek says he and his colleagues are trying to put a human on a chip.

One with a heart, cardiovascular and nervous systems, a kidney and a liver. Not to mention a gastrointestinal tract.

Unlike you and other folks, the array would consist of only a small amount of cells. But enough to mimic the way your body reacts to the presence of toxins – that is to say, badly – and at very low levels, making for a highly sensitive sensor system.

The U.S. Army Construction Engineering Research Lab chemist recently outlined one experiment using cells to detect water contamination. The researchers at the Army lab in Champaign and the University of Illinois aren't even much worried about detecting what the contaminants are at this point.

They're using the cell-based sensors to try to pick up the presence of toxic materials, whatever they are. The cells signal a toxic assault by giving off a specific flavor of oxygen, which can be detected to provide a warning.

"We can say there's something in that water that's toxic to cells," Cropek said recently. "We're not trying to say what it is. We're just trying to detect that."

That kind of limited "toxicity sensor" could be sufficient in some situations, a soldier testing water in the field, for example.

"He doesn't necessarily care what's in there, he only cares if it can kill him or not," said Cropek, whose research focuses on using biomaterials for detecting on a molecular scale substances of interest to the Defense Department, such as chemical weapons or explosives.

CERL and UI researchers also are trying to get heart cells to line up in tiny channels on a chip and fashion a cellular fiber that actually beats like a heart.

The idea is that changes in the beat in response to the presence of toxins may be readable, making for a mechanical rather than chemical sensor, Cropek said.

Cropek collaborator Irene MacAllister, also a CERL researcher, highlighted another test employing thyroid cells to detect minuscule amounts of perchlorate in drinking water, which affects the thyroid gland and can be a risk for pregnant women and their fetuses and for newborn children.

Cropek emphasized that a lot of those ideas are mostly conceptual at this point.

But he's already won awards for work employing DNA molecules in sensors designed to identify lead and uranium traces in less than a couple minutes and with parts-per-trillion accuracy. Cropek has collaborated with UI Professor Yi Lu on that research.

Lu, a UI chemistry professor, co-founded a company, DzymeTech, to bring lead test kits to market, with the idea that homeowners and home inspectors could use them to check for lead in paint or water.

In addition to finding a place in environmental monitoring in general, the technology could benefit Army testing and remediation efforts involving lead and uranium in particular, said Dana Finney, spokeswoman for the lab. Known as CERL, the lab researches ways to better build, operate and maintain military facilities, among other things. Many of its developments find uses in civilian life as well.

Cropek also works with UI researchers Tulika Dalavoy, Mark Shannon and Jonathan Sweedler and former UI Professor Paul Bohn, now at Notre Dame, along with researchers at Colorado State, Columbia, Cornell, Harvard and MIT. Besides MacAllister, CERL researchers Thuy Bui, Puneit Dua and Bharathi Pamidighantam are part of his team.

Despite their broad interest in cell-based sensors, they're not done with DNA. Cropek said they are looking at DNA aptamers, strands selected or engineered to bind or react to specific targets, for use in detecting explosives.

Unlike lead or uranium, the presence of explosives residue doesn't appear to cleave DNA molecules to provide a signal that can be used in a sensor. But explosives might be identifiable by tracking shape changes in the ribbon-like molecules as a result of the explosives' presence.

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