The test, which is faster than existing whole-blood immunoassays, uses gold nanoshells, tiny optically active gold-coated glass particles that are so small about 700 could fit in the diameter of a human hair.
In laboratory tests at Rice, the nanoshell immunoassay was capable of detecting less than one billionth of a gram of the glycoprotein immunoglobulin G, or IgG, per milliliter of whole blood.
"To our knowledge, this is the first in situ whole-blood immunoassay to report sensitivities on this order in under 30 minutes," said Jennifer West, associate professor of bioengineering and chemical engineering.
Immunoassay technology capitalizes on the characteristic way that antibodies attach themselves to invading pathogens in the body. Antibodies are proteins produced by white blood cells. Their job is to recognize and bind to invading antigens in the body, and they do this with great specificity. Scientists and doctors have discovered numerous ways to harvest these antibodies and use them diagnostically to identify a multitude of different chemicals.
One of these diagnostic applications is the conventional immunoassay, in which a solution that a doctor wants to test, such as blood plasma, is exposed to a tray containing antibodies that bind with a specific antigen under investigation. When the antibodies bind to the antigen, the test changes color. These systems are used to identify and diagnose various conditions ranging from HIV to a heart attack.
Unfortunately, existing technologies haven't produced a fast, reliable whole-blood immunoassay, in part because blood is so viscous and murky that it
Contact: Jade Boyd