On the dynamics of semiflexible fibrin gels

Abstract

The internal dynamics of semiflexible fibrin gels has been investigated by means of dynamic light scattering (DLS). Fibrin gels, grown at room temperature from fibrinogen solutions at different NaCl concentrations, exhibit rather different structural features. High salt concentrations produce “fine” gels characterized by thin fibers and small mesh sizes, while low salt concentrations give rise to “coarse” gels with thick fibers and much larger mesh sizes. The observed dynamics of these two kinds of gels are quite different as well. “Fine” gels behave as typical semiflexible polymer gels, in which the dynamic structure factor f(q,t) shows an initial monoexponential decay followed by a stretched exponential decay, f(q,t) ∼ exp -(Γqt)β. Conversely, “coarse” gels exhibit a highly arrested dynamics, in which the dynamic structure factor does not relax to zero, but decays to a plateau whose value depends on the scattering wavevector q. Moreover, only the stretched exponential decay is observed at the fastest decay times, with the exponent β = 0.63±0.07 being independently of q. This behaviour can be interpreted as given by the contributions of the internal elastic modes of many different length scales.