Wednesday, April 04, 2007

Sandia handheld instrument assesses dental disease in minutes

Further uses may include faster diagnosis of breast and prostate cancer, easier measurement of animal serum in vaccines, and rapid detection of biotoxins
Sandia researcher Amy Herr prepares human saliva samples for analysis that will be conducted using Sandia’s lab-on-a-chip clinical diagnostic instruments Sandia researcher Amy Herr prepares human saliva samples for analysis that will be conducted using Sandia’s lab-on-a-chip clinical diagnostic instruments. (Photo by Randy Wong)
Download 300dpi JPEG image, “saliva.jpg,” 376KB (Media are welcome to download/publish this image with related news stories.)

ALBUQUERQUE, N.M. — Who would have guessed that when the Star Trek medical diagnostic tool known as the tricorder makes its appearance in real life, the first user might be . . . your dentist.

According to a paper in the March 27 issue of PNAS (the Proceedings of the National Academy of Sciences), a recently completed pilot study conducted with the University of Michigan shows that a Sandia National Laboratories handheld device determined in minutes — from a tiny sample of saliva alone — not only if a patient has gum disease but quantitatively how advanced the disease is.

“The gold standard for any medical test is when instruments are used to examine human patients,” says Sandia researcher Amy Herr. “The pilot study allowed us to compare our results to accepted clinical measurements. Then we could statistically validate both the periodontal disease biomarker and the new microfluidic instrument.

“We achieved faster and more reproducible results because we combined steps that ordinarily require time-consuming manual handling by many people, into a single automated device.”

Using a disposable lab-on-a-chip cartridge, the device makes use of a molecular sieve made out of a polyacrylamide gel. The location of the sieve in the microfluidic chips is determined using photo-lithographical methods adapted from the semiconductor industry. The gel is porous, with very small openings. A low electrical current (measured in micro-amps) is passed through the gel and a process called electrophoresis moves charged proteins through it. The gel has a gelatin-like consistency and, by permitting the easy passage of smaller molecules and slowing the passage of larger ones, quickly separates proteins contained in the saliva. Prior to this separation, the proteins are brought into contact with specific antibodies chosen on their ability to bind to the biomarkers. The antibodies are pre-labeled with fluorescent molecules attached to them. Interrogation by laser of these combined molecules — fluorescent antibody and fluorescent antibody bound to the biomarker — determines the amount of biomarker present, indicating the degree of periodontitis.

Read the entire press release by clicking here.



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