Gold-DNA Combination May Lead To New Ways To Detect Diseases

August 22, 1997

Evanston, Ill. --- Researchers at Northwestern University have combined gold and DNA in an innovative way that should lead to new techniques for detecting many

types of diseases. Screening for genetic and pathogenic diseases -- that is, those transmitted through heredity and those transmitted by microorganisms -- may be done using the new material, according to one of its inventors, Chad A. Mirkin, professor of chemistry at Northwestern.

Research results reported in today's issue of Science magazine show that the procedure has a consistently high level of accuracy. "This process is likely to be faster, cheaper and more selective than existing diagnostic tools," Mirkin said. The new material is a probe made up of gold nanoparticles combined with oligonuceotides, strands of artificial DNA. Placing strands of a target DNA into a solution of the gold-DNA probes induces a chemical reaction that can be seen as a change in color from red to blue if genes linked to a particular disease are present. This color change can be readily sen en n the presence of bodily fluids such as urine or saliva.

Currently, diagnosis of such diseases frequently requires the use of radioactive phosphorus or sulfur tracers in the probes. This requires specially trained personnel, creates disposal problems and uses material with short shelf lives. Using the new gold-DNA probes eliminates those problems, because no radioactive materials are used, and the solution is stabilized to give it the longer shelf life needed for a useful diagnostic tool.

The new findings expand on earlier research by the Northwestern group, which develped the process for tailoring the optical, electrical, mechanical and structural properties of the gold-DNA combination material. Nanoparticles have a diameter one-billionth of a meter, so small they can't be seen with conventional microscopes.

Mirkin, a materials chemist, and his colleague, Robert Letsinger, chemistry professor emeritus, have been developing the technique for several years. Letsinger is a pioneer in the fabrication of artificial DNA. In addition to Mirkin and Letsinger, co-authors of the Science paper are post-doctoral assistant Robert Elghanian and graduate students James J. Storhoff and Robert C. Mucic.

In addition to medical diagnosis, the new material could be used for analysis in forensics, mass screenings for pathogens in clinical or laboratory settings and detection of biological weapons, Mirkin said.

Northwestern University

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