Low-cost assay would be a boon in remote areas, war zones, and emergency departments by providing fast and reliable blood typing without the need for specialized clinical lab equipment, and by reducing demand on type-O blood supplies
Such an inexpensive, simple-to-use assay would be game changing for pathology groups and clinical laboratories since traditional tests to classify blood into blood groups remain time consuming and labor intensive despite recent advances.
Changing Colors Reveal Blood Type
“In our proof-of-concept experiment, we used the rapid reaction between albumin and BCG [bromocresol green dye] to substantially reduce the analytical time without compromising specificity and sensitivity,” the researchers wrote in the study.
Dye-assisted paper-based test strips use immobilized antibodies and green dye for rapid and reliable blood grouping. A visual readout that changes colors reveals the different blood types. A teal square appears if an antigen is present, while a brown square appears if it is not.
When tested on 3,550 human blood samples the assay was 99.9% accurate. ABO antigens and five major Rhesus Rh antigens could be detected within 30 seconds. More rare blood types were determined in less than two minutes without centrifugation.
Paper Assays Reduce Need for Clinical Laboratories to Type Blood in Three Critical Settings
While conventional blood grouping that uses a gel-card assay takes up to 20 minutes and is labor intensive, Zhang managed to drastically reduce the time needed to determine blood type. He did that by turning the two-step process of forward-typing (detecting the presence or absence of A and/or B antigens in a person’s red blood cells) and reverse-typing (testing a patient’s serum for the presence of ABO antibodies) blood into one step. In an article for STAT, Zhang stated that his paper assay includes a filter that separates the blood needed for forward typing from the plasma needed for reverse typing.
“The red blood cells will stop swimming, while the plasma will go ahead alone along the strip,” Zhang explained.
In the published study, the research team stated that they had produced blood-grouping formats fitting three different clinical requirements:
• Emergency use;
• Clinical use; and
• A rare group format for specialized applications.
Zhang and colleagues emphasized the importance of the blood-typing platform they have designed.
“The accurate identification of human blood systems is essential to avoid incompatible transfusions,” the authors stated in the study. “We designed and developed a dye-assisted paper-based test for rapid blood grouping using a newly developed dye-based readout strategy to conquer long-standing problems with conventional methodologies, such as long turnaround times, labor-intensive operation, and technical training requirements.”
Blood Test Most Beneficial in Remote Areas and Trauma Centers
Creation of such an inexpensive, quick test for determining a patient’s blood type would be a boon for remote areas, wars zones, and trauma units. It would reduce the need to stockpile type O-negative blood, which can safely be given to patients of all blood types.
In an article for New Scientist, Janet Wong, MD, Transfusion Medicine Specialist for the Australian Red Cross Blood Service, stated that the reliance on type-O blood creates problems for hospitals since only 1-in-15 potential blood donors have O-negative blood. “The demand is already extremely high and it’s getting higher,” she said.
Another Paper-based Diagnostic Test Joins the Line-up
The researchers describe the cost of their paper strip as “economical,” which falls in line with other paper-based diagnostics. In a previous e-briefing, Dark Daily reported on Massachusetts Institute of Technology’s paper-based urine test that can detect colorectal cancer and thrombosis. It was heralded as accurate, inexpensive, and simple enough to use in developing countries.
The Chinese team predicts that further development of its blood typing mechanism will result in “highly compact and fully automated platforms that are highly efficient and economical, making large-scale manufacturing possible.” Zhang told New Scientist he expects the product to be available in the market within one to two years.
Many point-of-care mobile diagnostics have entered the market in the past few years. Each one altered the workflow for clinicians, diagnosticians, and medical laboratories. If this new paper-based blood test assay works as promised, and reaches the US, it will likely also further the diagnostic industry’s evolution toward compact, mobile, point-of-care testing.
—Andrea Downing Peck