May 3, 2012
Blood Test Spells Out Blood Types
Connie K. Ho for RedOrbit.com
Researchers at Monash University recently developed a paper-based device that writes blood type as text and can be used by emergency-response teams in humanitarian disasters.
The study, published in the journal Angewandte Chemie, describes how the sensors uses the ABO system, categorizing blood types as A, B, AB, or O and positive or negative. The system designates which antigens are in the blood (i.e. A blood has A antigens, B blood has B antigens, and blood type O has no antigens).
Lead researcher Professor Wei Shen of Monash University was inspired to create the device after watching the film, Harry Potter and the Chamber of Secrets. In one scene, Harry writes a question on a paper about the Chamber of Secrets and the paper responds with an answer in writing.
"The movie shows that you can have a text result, and that's where the idea comes from," Shen stated in an abc.net.au article.
Shen believes that the blood test can come in handy, as sometimes mistakes made during blood test interpretation can have serious consequences.
"We found that more than 80% of the population“¦ could not interpret the result even if the result from a perfectly functioned blood typing assay was presented to them," commented Shen in an article by the BBC article. "But with a device that can spell out the patient's blood type in written text, people will know their blood type easily."
The team found that the paper-based blood test device they developed was comparable to the ones used in hospitals, with theirs being cheaper, faster, and easier to use.
"We have tested 99 samples and so far we have found it has the same accuracy as the mainstream blood typing tests," Shen told abc.net.au.
With such user-friendly capabilities, the groundbreaking device could be used in developing countries as well.
"Studies show that errors are linked mostly to incorrect registration of the results to the blood sample, or human error," Shen told BBC News. "In developing regions and remote areas, mainstream technologies are not available, and non-mainstream methods are used. Misinterpretation of assay results by less-trained health personnel is likely to be a major worry."
The tool is made of a small, square-shaped paper-based sensor that has a layer of water-repellant coating, except for four areas on the surface that are shaped in different blood letter types. For example, one area is shaped in the letter “A,” another area shaped in the letter “B,” and another area has the “minus” sign. These areas can absorb liquid and contain antibodies to interact with blood cells, clumping based on the type of blood it is.
So, when blood type B is dropped on the paper, it will fill the part of the paper that has antibodies responding to blood type B, creating a letter “B” on the paper. The letter is readable even when the sensor has water on it. Since blood type O has no antigens, the researchers filled that area with antigens that were opposite to antigens A and antigens B. If the blood sample was not O, then the antigens would fill it and it would make an “X” mark. However, if the blood sample was blood type O, when the paper was washed with saline liquid, the researchers would be able to see that there was an X marked in white with a red letter O left, signifying that the blood sample was blood type O.
"The major novelty is in the ease of reading the strip by spelling out the letters for specific blood types,” explained Dr. John Brennan, the Canada Research Chair in Bioanalytical Chemistry, in an interview with BBC. "I think that there are places where such strips might be used, such as rapid response scenarios - battlefield casualties, automobile accidents, etc - where rapid blood transfusion is required. In such cases an unambiguous readout such as that provided by these strips would be important."