A surface-functionalized whole blood-based dielectric microsensor for assessment of clot firmness in a fibrinolytic environment

Accurate assessment of fibrin clot stability can predict bleeding risk in coagulopathic conditions such as thrombocytopenia and hypofibrinogenemia. Hyperfibrinolysis — a clinical phenotype characterized by an accelerated breakdown of the fibrin clot — makes such assessments challenging by obfuscating the effect of hemostatic components including platelets or fibrinogen on clot stability. In this work, we present a biofunctionalized, microfluidic, label-free, electronic biosensor to elicit unique, specific, and differential responses from the multifactorial processes of blood coagulation and fibrinolysis ex vivo. The microsensor tracks the temporal variation in the normalized real part of the dielectric permittivity of whole blood (<10 μL) at 1 MHz as the sample coagulates within a three-dimensional, parallel-plate, capacitive sensing area. Surface biofunctionalization of the microsensor’s electrodes with physisorption of tissue factor (TF) and aprotinin permits real-time assessment of the coagulation and fibrinolytic outcomes. We show that surface coating with TF and manual addition of TF result in a similar degree of acceleration of coagulation kinetics in human whole blood samples. We also show that surface coating with aprotinin and manual addition of aprotinin yield similar results in inhibiting tissue plasminogen activator (tPA)-induced upregulated fibrinolysis in human whole blood samples. Validated through a clinically relevant, complementary assay — rotational thromboelastometry for clot viscoelasticity — we finally establish that a microsensor dual-coated with both TF and aprotinin detects the hemostatic rescue in the tPA-induced hyperfibrinolytic profile of whole blood and the hemostatic dysfunction due to concurrent platelet depletion in the blood sample, thus featuring enhanced ability in evaluating complex, combinatorial coagulopathies.