Relaxation Dynamic Measurements in Fibrin Networks

Quasi-elastic light scattering measurements of the normalized time-dependent density correlation function, g(t), have been carried out on fibrin networks formed at T equals 25 degree(s)C from fibrinogen solutions. Fibrinogen is a protein present in vertebrate body fluids, which is capable of forming gels because of an initial activation and a successive polymerization process. The correlation function g(t) has been systematically measured as a function of the fibrinogen concentration in solutions at a fixed pH 8, activated by 400 nM of thrombin. As the fibrinogen concentration increases from 84.5 nM to 880 nM, g(t) exhibits pronounced nonexponential relaxation. The stretched exponential function e-(t/τ) β has been shown to fit the g(t) function over a four decade time range of measurement, for q values ranging between 1.32 X 105 cm-1 and 2.45 X 105 cm-1 stretched exponent (beta) equals 0.65 +/- 0.05, commonly observed near the glass transition point, has been obtained. The average decay rate (lambda), accounting for short time decay rates of g(t), decreases as concentration increases showing a minimum at p equals 400 +/- 50 nM, while the relaxation time τ shows a maximum at the same concentration.