Devices made with cheap strips of paper have outperformed two other testing methods in detecting malaria infection in asymptomatic people in Ghana — a diagnostic advance that could accelerate efforts to eliminate the disease, researchers say.
Deceptively simple in appearance, the devices facilitate chemical reactions between a drop of blood and molecules embedded into paper layers and rely on sophisticated, but portable, instrumentation to make the diagnosis: a mass spectrometry measurement of the final product — in positive cases, a malaria-specific antigen that triggers the immune system.
Researchers created a 3D automation process of storing antibodies and ions in the device and added a multipronged molecule to amplify the compound signal for detection by mass spectrometry, but the device fabrication process is still manual. Sheets of paper composing the device’s layers — coated with waxy sections that keep blood from seeping through — are printed individually and pressed together with double-sided tape. Twenty-five devices fit onto the 8 × 12-in. sheets.
Once applied, the blood is separated into four chambers — two acting as positive and negative controls — and induces chemical reactions as it passes through the layers. The chemists designed ionic probes to tag antibodies that extract the antigen from the blood and place it permanently onto the paper within about 10 minutes. Following a buffer wash, the strips are peeled apart and waved in front of a handheld mass spectrometer. (Image credit: NIAID)
For more information, visit here .
