A team of researchers has developed a method to test for infectious diseases in 20 minutes using a glowing paper strip, a drop of a patient’s blood, and a digital camera. In developing countries, the low-cost test has a lot of potential for quickly testing for tropical diseases.
The test detects the presence of infectious diseases by looking for specific antibodies in the blood that the body produces in response to viruses and bacteria, for example. Not only is the test a low-cost, quick alternative to costly, time-consuming laboratory measurements in hospitals, but it may also be useful in regularly monitoring the dose of antibody medicines to take corrective measures in good time.
The underside of the paper emits blue-green light as a result of a biochemical reaction. The higher the concentration of antibodies, the bluer the color. A digital camera, such as one found on a cell phone, is sufficient to determine the exact color and, thus, the outcome.
A luminous sensor protein developed at TU/e is embedded in the paper strip. When a droplet of blood falls onto the paper, this protein causes a reaction that produces blue light (known as bioluminescence). For example, an enzyme that illuminates fireflies and certain fish plays a role. The blue light is then converted into green light in a subsequent step. When an antibody binds to the sensor protein, it prevents the second step from occurring. A lot of green indicates a low number of antibodies, while less green indicates a higher number of antibodies.