An array of the silicon nanobiochips developed by the McDevitt research team. The bead ensembles in the center of each chip are sensor sites for a saliva diagnostic test that can detect early signs of breast cancer.
The lab-on-a-chip system miniaturizes a test that is traditionally conducted in large labs. Its concept was born more than a decade ago at UT with the help of professors John McDevitt, PhD, and Charles Streckfus. DDS. They were working independently on different elements of saliva-based diagnostics at separate campuses of UT.
At the UT dental branch at Houston, Streckfus was conducting research from a clinical perspective to look for proteins in saliva that would indicate the early stages of breast cancer. Streckfus is a professor of diagnostic sciences.
McDevitt, professor of chemistry and biochemistry at UT's Austin campus, was examining the test's mechanical aspect. This involved developing next-generation diagnostic tools.
About a year ago, the professors began talking about Streckfus's work in saliva diagnostic studies of cancer patients and how McDevitt's group could adapt its sensor to breast cancer diagnosis.
“Through this collaboration, we're beginning to reprogram our miniaturized sensor,” says McDevitt. “We've jointly been developing this effort, but the miniaturized platform that we're using has a longer history.”
Charles Streckfus (left) has been working for a decade to develop the saliva-based cancer diagnostic.
McDevitt likens the test's operation to an automated teller machine system. Its main components are a nanobiochip, which contains the sample, and an analyzer that identifies the proteins. The miniaturized chip is packaged in a structure that is about the size of a credit card (2 × 3.5 in.) but twice as thick. The way in which the test processes samples is straight forward. After a patient spits into a cup, the saliva is transferred onto a card that is fed into an analyzer. About the size of a toaster, the analyzer contains a series of mechanical actuators, optics, and a computer.
The inexpensive test has global potential. It could be used as a primary test in developing nations that don't have mammography centers, or as an adjunct to a mammography in wealthier countries.
Because results are produced in just 15 minutes, the patent-pending test could be conducted during one visit to a doctor's office. It's also expected to minimize the occurrence of false-
positive and false-negative results. The technology could serve as a comfortable alternative to the mammogram, which means that women might opt to be tested more frequently. Regular testing is key to early detection.
The microchip used as a sensor system in a saliva diagnostic test as seen with a scanning electron microscope.
In the future, the test could be used to detect oral and cervical cancer, and even heart disease. Streckfus also suggests that a universal test to detect cancer could be designed with subsets of markers. Theses subsets would provide information about a tumor's location.
The researchers need about another year to identify the specific biomarkers that must go into the final system. “We have some good results on some initial biomarkers, but with the paper [Streckfus] just published, there's a series of about three dozen other candidates that we want to look at carefully,” says McDevitt.
Streckfus's work that examined identifying protein markers in saliva to diagnose breast cancer was published in the January 10, 2008 issue of the journal Cancer Investigation.
After establishing the biomarkers, the group will begin looking for commercial partners. McDevitt estimates FDA approval, manufacturing, and distribution will take about three years. He hopes to have the device on the market in four years.