Comparison of surface plasmon resonance and quartz crystal microbalance in the study of whole blood and plasma coagulation.

The coagulation of blood plasma and whole blood was studied with a surface plasmon resonance (SPR) based device and a quartz crystal microbalance instrument with energy dissipation detection (QCM-D). The SPR and QCM-D response signals were similar in shape but differing in time scales, reflecting differences in detection mechanisms. The QCM-D response time was longer than SPR, as a physical coupling of the sample to the substrate is required for molecules to be detected by the QCM-method. Change of sample properties within the evanescent field is sufficient for detection with SPR. Both the SPR signals and the QCM-D frequency and dissipation shifts showed dependency on concentrations of coagulation activator and sensitivity to heparin additions. The ratio of dissipation to frequency shifts, commonly considered to reflect viscoelastic properties of the sample, varied with the concentration of activator in blood plasma but not in whole blood. Additions of heparin to the thromboplastin activated whole blood sample, however, made the ratio variation reoccur. Implications of these observations for the understanding of the blood coagulation processes as well as the potential of the two methods in the clinic and in research are discussed.