Modeling of fibrin gels based on confocal microscopy and light-scattering data

Fibrin gels are biological networks that play a fundamental role in blood coagulation and other patho/physiological processes, such as thrombosis and cancer. Electron and confocal microscopies show a collection of fibers that are relatively monodisperse in diameter, not uniformly distributed, and connected at nodal points with a branching order of ∼3-4. Although in the confocal images the hydrated fibers appear to be quite straight (mass fractal dimension D_m = 1), for the overall system 1m0 between their centers of mass so that they are overlapped by a factor η = ξ/ξ₀ and have D_m ∼1.2-1.6. The in silico gels' structure is quantitatively analyzed by its 3D spatial correlation function g_3D(r) and corresponding power spectrum I(q) = FFT_3D[g_3D(r)], from which ρ, d, D_m, η, and ξ₀ can be extracted. In particular, ξ₀ provides an excellent estimate of the gel mesh size. The in silico gels' I(q) compares quite well with real gels' elastic light-scattering measurements. We then derived an analytical form factor for accurately fitting the scattering data, which allowed us to directly recover the gels' structural parameters.