Blood plasma coagulation studied by surface plasmon resonance

A surface plasmon resonance (SPR) apparatus was used to investigate blood p lasma coagulation in real time as a function of thromboplastin and heparin concentrations. The response curves were analyzed by curve fitting to a sig moid curve equation, followed by extraction of the time constant. Clotting activation by thromboplastin resulted in increased time constant, as compar ed to spontaneously clotted plasma, in a dose dependent way. Addition of he parin to the thromboplastin-activated plasma counteracted this effect. Atom ic force microscopy (AFM) pictures of sensor surfaces dried after completed clotting, revealed differences in fibrin network structures as a function of thromboplastin concentration, and the fiber thickness increased with dec reased thromboplastin concentration. The physical reason for the SPR signal observed is ambiguous and is therefore discussed. However, the results sum marized in the plots and the fibrin network properties observed by AFM corr elate well with present common methods used to analyze blood coagulation. ( C) 2000 Society of Photo-Optical Instrumentation Engineers. [S1083-3668(00) 00901-1].