To facilitate diagnosis in remote, low-resource settings, researchers have developed a paper-based device that changes color, depending on whether the patient has Ebola, yellow fever, or dengue. The test takes minutes and does not need electricity to work.
The test uses silver nanoparticles in a rainbow of colors. The sizes of the nanoparticles determine their colors. Therefore, the team uses different sizes of these chemical ingredients for various hues. The researchers attached red, green, or orange nanoparticles to antibodies that specifically bind to proteins from the organisms that cause Ebola, dengue, or yellow fever, respectively. They introduced the antibody-tagged nanoparticles onto the end of a small strip of paper. In the paper's middle, the researchers affixed “capture” antibodies to three test lines at different locations, one for each disease.