Wow, new paper based test can tell your blood group in 30 seconds!

Researchers working at the Third Military Medical University in Chongqing, China have developed a quick and reliable test to know the blood type in seconds and rapidly determine the compatibility of donor and recipient blood samples before transfusion.

A conventional test take 10 or 20 minutes to verify someone’s blood type which is the reason why most emergency departments stock only type O blood, which can safely be given to anyone because it lacks the antigens that trigger immune reactions.

Zhang et al test is paper based and relies on the color changes that occur when immobilized antibodies and bromocresol green dye (BCG) react with blood components resulting in color changes that can be readout visually by naked eyes. The paper was published in Science Translational Medicine on 15 March 2017.

Rapid and accurate blood typing is a key component of managing medical emergencies especially in ER and trauma centers. It has the ability to save lives because of saving precious time and avoiding incompatible blood transfusion.

The rapid test gets over the many longstanding problems of older tests like requiring sophisticated instruments, lengthy procedure, requiring expertise and time consuming.

The test is based on the ability of human serum albumin (HSA) to react with the yellow monoanionic dye bromocresol green (BCG) which results in teal BCG-HSA complex in an acidic environment, whereas whole blood produces a brown complex after reacting with BCG, which is easily distinguished with the naked eye.

The test simultaneously performs both F&R tests using a single POC chip, forward grouping identifies specific antigens on RBCs, whereas reverse grouping detects antibodies in plasma on the basis of RBC agglutination. F&R tests are widely used before matching donor and recipient blood before blood transfusion.   

Schematic of the fast blood-grouping devices
Designs, testing procedures, and results of our (A) ABO forward strip, (B) F&R assay, and (C) ABO and Rh group multiplex antigen assays. I and II represent the forward blood-grouping observation windows; III and IV represent the reverse blood-grouping observation windows. The observation zone is located between the two dotted lines as shown in the platforms of the ABO and Rh group assays (C). A strip without antibody (BCG only) was used for quality control (Q)

Using the BCG bio sensing mechanism, the authors developed three test formats to meet various clinical situations: a fast ABO forward and ABD (ABO and Rh D) test for emergency use, an ABO F&R format and an ABO/Rh format (A/B/D/C/c/E/e) for routine clinical tests, and a rare group format for specialized applications.

For quick blood grouping 15 μl of fresh or anticoagulated whole blood was dropped onto the sample zone and incubated for 20 s to allow all specific RBCs to bind to the immobilized specific IgM antibody. Then, 30 μl of elution buffer was introduced to elute the nonagglutinated RBCs and plasma, followed by a color change in the detection zone within 30 s. F&R assay and ABO/Rh group assay required a little more blood and 2 minutes’ time.

The team performed the test on 3550 human blood samples, the strip was more than 99.9% accurate, and only took 30 seconds to complete.

A machine learning method was developed to eliminate the human error and get consistent results and reproducibility by reading the colorimetric assay readouts.

When commercially available it can be of use in resource limited areas, war zones and in emergencies where seconds also matter to save lives. It can be of developed into cost effective universal blood grouping method. 

The full article titled " A dye-assisted paper-based point-of-care assay for fast and reliable blood grouping"  in Science Translational Medicine.