WIKIMEDIA, MARGRETTE DOMWhile existing tests can take anywhere from 5 to 20 minutes and require two steps to complete, a new paper-based diagnostic method, described in a paper published yesterday (March 15) in Science Translational Medicine, takes just 30 seconds to reveal whether a person is type A, B, or O, and a total of two minutes to reveal a whether the person is “positive” or “negative” for Rh factor, all with just one step.

Traditionally, blood typing requires forward typing, in which antibodies found in type A and type B blood are added to a blood sample to test for reactivity, followed by reverse typing, in which serum (cell-free blood) is mixed with the blood type identified in the first test. This stepwise process requires the separation of the serum using a filter—a procedure best carried out in a laboratory setting—and because the steps must be conducted...

The new test, on the other hand, uses a paper strip that is coated in antibodies that recognize antigens found in different blood types, plus a commonly used green dye. When a drop of blood is put on the strip, it is wicked through the different types of antibody, turning squares either teal (if the antigen is present) or brown (if it’s not).

Hong Zhang of Third Military Medical University in Chongqing, China, and colleagues analyzed more than 3,500 blood samples with their paper strip with more than 99.9 percent accuracy, according to the study. In addition to being faster and more cost-effective in traditional settings, the test’s ease of use could prove invaluable for remote areas or war zones, where typically O blood (the “universal donor” type) is given because blood-type testing is impractical, Zhang told New Scientist. “We are expecting that we can see this product in the market within 1-2 years.”

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