Rheological Properties of Fibrin Clots

  • Yun-Chu Chen

Student thesis: Master of Philosophy


A study of the rheological properties of fibrin, an important coagulant in human haemostasis, is presented in this MPhil thesis. Fibrin monomers are activated at the site of an injury to a blood vessel through the thrombin-induced cleavage of fibrinogen, a protein which circulates in the blood. These monomers self-assemble into networks by branching out and connecting with each other. This is the process which gives rise to a blood clot. There are a variety of factors which have an influence on the structure of the fibrin network, which in turn have an influence on the physical properties of the clot. The influence of two of these factors, fibrinogen concentration and thrombin concentration, is investigated in this paper. The motivation for this work is the need to determine what makes a perfect blood clot, and to find out if increasing the concentration of fibrinogen or thrombin increases the long-term stability of clots. Previous research has highlighted some of the remarkable rheological properties of this material, namely by frequency-dependent experiments. In this work frequency-independent measurements of the time evolution of fibrin clot rigidity, and how this is related to the concentration of thrombin and fibrinogen, are presented. Measurements were taken using a Bohlin Gemini HR Nano Rheometer over a period of 16 hours. Samples were prepared with Tris-EDTA buffer, both with the addition of salt and without, either with a fixed concentration of thrombin and varying fibrinogen, or with a fixed concentration of fibrinogen and varying thrombin. It was found that the time evolution of the rigidity exhibited three separate phases, characterised by a steady increase in rigidity, followed by a sharp increase, and ending with a plateau, during which rigidity ceased to increase. Samples prepared with a higher concentration of thrombin or fibrinogen exhibited an increase in rigidity in the first phase, but this behaviour is not observed after the first phase. Consistent with previous research, it was determined that the clotting time of fibrin decreases with increasing concentration of thrombin or fibrinogen. This effect is also observed when salt is added to the Tris-EDTA buffer. The addition of salt was also found to have an effect on the long-term stability of clots, as the rigidity of samples prepared with salt experienced a sharp decline in the third phase. This can be related to the structure of fibrin, and the findings in this work can be used to help increase our understanding of how to make a perfect clot.
Date of Award31 Dec 2012
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorThomas Waigh (Supervisor)


  • rheology
  • fibrin
  • thrombin
  • blood clot

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