The Daily Illini
November 17, 2000

Chemistry Professor develops Fast Lead detection Using DNA

by Tom Polansek,

Courtesy of Yi Lu

Professor Yi Lu, director of research, and Jing Li, former graduate student, invented the catalytic lead sensor. This new method is a great advancement in clinical toxicology and will make it easier to detect lead and other metals in the human body. Jing Li graduated from the University with a Ph.D. last June.

Associate professor of chemistry Yi Lu has developed a new method of detecting lead using DNA sensors to return results more quickly and for less cost than the current method.  Exposure to lead can lead to serious neurological damage, including intelligence deficits, trouble with fine motor skills, hearing impairment and seizures.  "Our goal is to detect the lead before it has an effect, like in drinking water," Lu said. "The DNA is very sensitive and gives a reading right on site and in a time-dependent fashion."  Lu said the lead-detecting DNA sensors glow like lightning bugs in the presence of even very small amounts of lead. So far, levels of lead 50 times below the amount considered dangerous have been detected by the sensor.

Lu explained that DNA is fluorescent in its natural state, so he and co-workers applied a "quencher" to the DNA to shut off the fluorescence. Then, the lead-reactive DNA was developed in a way so that when it is put in the presence of lead, the quencher cleaves off and the DNA glows again. The DNA shines more brightly in the presence of increasing lead levels.  Lu and graduate student Jing Li, co-author of the research study, did not know the exact DNA code for lead when they started their experiments six years ago.  The DNA fashioned by Lu is composed of the same material that makes up every human, but the sequence order of the code for lead detection is unique.  Lu is currently working with the college of engineering to develop a portable detection module so that the system can be easily used and marketed to the public. Current lead testing is expensive and time-consuming and requires that a sample of the material is dissolved in liquid and sent off to a lab.  Duane Cole, manager of the eastern division of the Illinois American Water Company, said that lead testing currently takes two weeks from the time that a water sample is collected until the time when a breakdown of its lead content is returned. All collected water samples have to be sent out to the water company's laboratory to be analyzed.  "If the testing is approved by the EPA, and it is a way to get results faster and for less expense, we would be interested," Cole said.

Many future developments in other areas might now be possible because of this breakthrough. Lu hopes that this DNA technology will eventually be used to detect other toxic substances, such as mercury and chromium-6, the chemical that contaminated the water in the movie Erin Brockovich, released in 2000.
Lu referred to this movie to explain the benefits of his system over current technology. In the movie, Julia Roberts' character collects a toxic water sample with her bare hands and then the sample is sent off to an analysis lab for several days before a conclusive result of the toxicity can be returned. With the advancements made by Lu and his team, Roberts' character could have brought a portable detection device system to the actual site with her and received a much quicker and cost-effective result.  Lu also envisions a time when technology for chemical testing will allow researchers to test possibly toxic samples without having to get too close to them.

"It is very dangerous to go test radium at weapons sites, for example," Lu said. "It is possible that we could do remote sensing through optical cables with DNA. We have a lot of hope."  Besides detecting hazardous conditions, DNA can also be used to monitor beneficial minerals, such as calcium.