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ORNL DNA biochip provides answers in matter of minutes

 

OAK RIDGE, Tenn., Dec. 10, 1997 — Within a couple of years, patients may have their test results for the AIDS virus, cancer, tuberculosis or other diseases before they leave the doctor's office.

A new "DNA biochip" developed by Tuan Vo-Dinh and colleagues at the Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL) could revolutionize the way the medical profession performs tests on blood. Instead of a patient having to wait several days for results from a laboratory, they are virtually immediate with the matchbox-sized biochip. And it requires less blood with no sacrifice in accuracy.

We're really excited about the possibilities offered by the biochip," said Vo-Dinh, a Life Sciences Division group leader who has developed several technologies with medical applications. "We've already successfully demonstrated the concept of the DNA biochip. Our next step is to extend the capabilities of the chip, including into environmental applications."

In addition to time savings, the DNA biochip eliminates the need for radioactive materials used as labels and common in many medical tests. This greatly reduces cost and potential health effects to technicians and lab workers handling samples and performing tests. It also reduces disposal costs because chemically labeled blood must be handled according to strict regulations.

To be useful for detecting compounds in a "real-life" sample, a biosensor must be extremely sensitive and able to distinguish between, for example, a bacteria, virus or another chemical or biological species. ORNL's DNA biochip does that, according to Vo-Dinh, who explained that the biochip mimics a living system's sophisticated recognition capability.

Unlike other biosensors based on enzyme and antibody probes, the DNA biochip is a gene probe-based biosensor. Gene probe-based biosensors offer excellent selectivity and sensitivity, making them important diagnostics tools for genetic diseases and infectious species.

"The DNA biochip opens a new world of diagnostics based on genetics," Vo-Dinh said. Non-DNA-based probes, such as the enzyme or antibody probes, look for antibodies or enzymes that occur in the presence of certain diseases or infections, so they provide only an indirect method of detection.

The development of non-radioactive gene probe biosensors required the integration of three major elements. ORNL researchers had to develop bioreceptor probes, luminescence or other techniques for optical detection and an electro-optic integrated circuit system on a single chip for biosensing.

"Our overall goal was to develop miniaturization technology that can be used to produce microchip biosensor devices," Vo-Dinh said. "Our next step is to extend the capability of the chip so it can detect hundreds of genes."

Prototyping could be done within about six months; Food and Drug Administration approval could take about a year and clinical trials could begin in another year, Vo-Dinh said. If everything goes smoothly, the DNA biochip could be in use in about two years.

Assisting in the development of the biochip integrated circuit were Nance Ericson and Alan Wintenberg of the laboratory's Instrumentation and Controls Division. The application and evaluation of the biochip technology also involved researchers Narayana Isola, J.P. Alarie and Guy Griffin of the Life Sciences Division.

The biochip is a spin-off of a 1994 Laboratory Directed Research and Development-funded project to develop advanced biosensors. The initial research led to the Surface-Enhanced Raman Gene (SERGen) Probe. The SERGen Probe simultaneously provides a simple, rapid and inexpensive test for the detection of multiple sequence-specific DNA fragments. Additional funding was provided by DOE's Office of Health and Environmental Research.

ORNL, one of DOE's multiprogram research facilities, is managed by Lockheed Martin Energy Research Corporation.


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