College of LAS « Illinois


A Colorful Sensor for Lead Paint

Detecting the presence of hazardous lead paint could become as simple as pressing a piece of wet paper against a wall and watching its color change, thanks to a new biosensor an LAS chemist built from DNA and tiny gold particles.

The United States banned lead paint in 1978, but it's still found in millions of aging homes across the country. That poses risks to young children, who sometimes ingest enough lead to cause brain damage. Lab tests to detect lead paint are accurate, but the portable test kits used by building inspectors sometimes fail to detect lead, or indicate it's there when it's not.

"Our sensor can overcome those shortcomings," says Yi Lu, a LAS professor of chemistry.

To build the novel biosensor, Lu and graduate student Juewen Liu first designed a special piece of DNA called catalytic DNA that binds lead but leaves other metals untouched. When there's no lead present, a second piece of DNA called substrate DNA helps corral the gold particles into a big clump, which turns them blue. But when lead is around, the catalytic DNA snips the substrate DNA, which prevents the particles from clumping and turns them red.

Unlike other lead sensors, this one can be tuned to accurately measure both diluted and concentrated samples. Lu recently received a grant from the U.S. Department of Housing and Urban Development to test the sensor in American homes.

October 2003