Fibrinogen is one of the first proteins to be depleted in heavily bleeding patients. In this study, we have developed a new paper-based diagnostic to quantify the fibrinogen concentration in blood at room temperature.
The ability to diagnose and treat
critically bleeding patients
can save more than 2 million lives a year. Diagnosing hypofibrinogenemia
is essential in these patients. Recently, with the development of
new handheld diagnostics, fibrinogen concentration can be measured
rapidly at the point of care. However, these diagnostics can only
work with plasma and hence need blood cells to be separated before
use. In this study, we demonstrate a handheld fibrinogen diagnostic
that works with whole blood. The test works by (1) forming a premixed
droplet of a whole blood sample and thrombin solution on a solid surface,
(2) allowing it to clot, and (3) dropping a paper strip on top. The
further that blood moves down the strip, the lower the fibrinogen
concentration. The diagnostic can easily measure plasma fibrinogen
concentrations below 1.6 g/L for blood samples with hematocrits between
40 and 50%. Furthermore, diluting blood samples not only increases
the test’s sensitivity but also eliminates the effect of hematocrit
and thrombin inhibitors. The test can be completed in 3–4 min,
making it suitable for diagnosing early hypofibrinogenemia and allowing
for fibrinogen replacement therapy in critically bleeding patients.
Safe blood transfusion requires compatibility testing of donor and recipient to prevent potentially fatal transfusion reactions. Detection of immunoglobulin G (IgG) antibodies requires incubation at 37 °C, often for up to 15 minutes. Current incubation technology predominantly relies on slow thermal-gradient dependent conduction. Here, we present rapid optical heating via laser, where targeted illumination of a blood-antibody sample in a diagnostic gel card is converted into heat, via photothermal absorption. Our laser-incubator heats the 75 µL blood-antibody sample to 37 °C in under 30 seconds. We show that red blood cells act as photothermal agents under near-infrared laser incubation, triggering rapid antigen-antibody binding. We detect no significant damage to the cells or antibodies for laser incubations of up to fifteen minutes. We demonstrate laser-incubated immunohaematological testing to be both faster and more sensitive than current best practice — with clearly positive results seen from laser incubations of just 40 seconds.
Detection of blood group antibodies is a crucial step for blood transfusion recipients and pregnant women to prevent potentially fatal haemolytic reactions. Due to the short, non-bridging structure of such...
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