Rapid and easily identifiable blood typing on microfluidic cotton thread-based analytical devices

In this study, we present a novel swing-elution-based method to achieve rapid, cost-effective, and easily identifiable blood typing assays. Specifically, the method aims to swing the microfluidic cotton thread-based analytical devices (μCTADs) in PBS solution to effectively elute free red blood cells (RBCs) and allow large agglutinated RBCs to remain to precisely determine the blood type. In order to ensure an easily identifiable blood typing assay, fast swing mode needs to be used, and the elution time is evaluated to be >50 seconds. The created μCTADs have been used to successfully classify ABO and RhD blood types in 56 blood samples. Finally, in order to enhance the convenience and portability of blood typing, a blood-typing chip that utilizes a PBS liquid bridge to effectively elute the free RBCs is designed and fabricated based on the above swing-elution principle. Compared with the traditional wicking-elution methods that rely on the wicking effect to weakly elute the RBCs, our method possesses a stronger elution effect to remove the free RBCs inside the inter-fiber gaps or adhered to the fiber surface, resulting in effectively enhancing the identifiability of the elution results and minimizing user interpretation error. Given the simplicity of the blood typing method, we believe that our blood typing method has great potential to be widely applied in resource-limited and developing regions.

Detection of weak D with a fully automated solid-phase red cell adherence system

BACKGROUND

Microplate agglutination methods (MAMs) and column agglutination technology are widely employed for red cell typing and can be automated. Some tests, however, such as detection of weak D, require manual testing. The possibility of detecting weak D by a solid-phase RBC adherence (SPRCA) test was studied in a fully automated system.

STUDY DESIGN AND METHODS

The results of 2609 blood samples, characterized as being D- or with a incomplete agglutination reaction, were analyzed for the presence of the weak D phenotype. The 2609 samples were tested by a weak D tube test (antiglobulin method) and a weak D-test with the new SPRCA method. When weak D was detected, which D epitope was involved and whether it was associated with a partial D phenotype were determined.

RESULTS

Weak D was detected in 60 (2.3%) of the 2609 samples. The 60 samples that were weak D by the tube test were also weak D+ with the new automated SPRCA test. The sensitivity and specificity for the new weak D typing method were 100 percent, when compared with the standard weak D manual test.

CONCLUSIONS

These results support the possibility of performing weak D detection with a SPRCA fully automated system. These preliminary results are encouraging, showing good sensitivity and specificity of the test. Detection of weak D will permit full automation of blood typing.

A novel microplate agglutination method for blood grouping and reverse typing without the need for centrifugation

BACKGROUND

Current agglutination tests and solid-phase adherence methods, employed as the techniques for RBC typing and antibody screening, require centrifugation and washing steps. This report describes a novel agglutination method for forward and reverse grouping that is based on the formation of an RBC monolayer on a microplate without the need for centrifugation and washing.

STUDY DESIGN AND METHODS

In a comparative study, 2225 samples from healthy regular blood donors were tested for ABO, Rh (D, C, c, E, and e), K, and reverse grouping, in parallel, by the new microplate agglutination method and a commercially available blood testing system, which served as a reference method.

RESULTS

In the case of forward grouping, 0.37 percent of samples tested were false negative in the new method and 1.35 percent tested false negative in the reference blood testing system. In addition, the reverse grouping reference method showed 0.4 percent false-positive and 2.6 percent false-negative results. In contrast, the new method gave false-positive results in only 0.09 percent and false-negative results in 0.67 percent of the cases tested.

CONCLUSION

These results, as well as the possibility of adapting this method to a fully automated system, suggest that our novel agglutination method could be an important contribution to the field of immunohematology.