The ELISA biochemical test -- one of the most widely used clinical, food safety, and environmental tests -- normally takes hours or even days to perform manually. Using a specially designed CD, engineers performed the test automatically, and in only one hour.
The patent-pending technology involves mixing chemicals inside tiny wells carved into the CD surface. The spinning of the CD activates the tests.
In a recent issue of the journal Analytical Chemistry, the engineers report that the CD successfully detected a sample of rat antibody -- a standard laboratory test -- using only one-tenth the usual amount of chemicals.
This first demonstration paves the way for CDs to be used to quickly detect food-borne pathogens and toxins, said L. James Lee, professor of chemical and biomolecular engineering at Ohio State. The same technology could one day test for human maladies such as cancer and HIV, using a very small cell sample or a single drop of blood.
Lee estimated that the first commercial application of the concept is at least two years away.
"This study shows that the technology is very promising, but there are challenges to overcome," he said. "We have been working on designing special valves and other features inside the CD, and better techniques for controlling the chemical reactions."
"When we work on the micro-scale, we can perform tests faster and using less material, but the test also becomes very sensitive," he explained. As chemicals flow through the narrow channels and reservoirs carved in the CD, interactions between individual molecules become very important, and these can affect the test results.