Figure 1.

(a) Collagen fibers are represented as a spatially periodic square array of fibers and our analysis is performed in a periodic unit cell shown by the dashed line. (b) Nanoparticles diffuse inside the fibrous medium (random walk domain). A second computational domain is constructed for the calculation of hydrodynamic interactions (Stokesian dynamics domain). At each time step of the random walk, the position of the particle is mapped to the Stokesian dynamics domain and its diffusion coefficient is calculated by the solution of a Stokesian dynamics problem. The diffusion coefficient is returned to the random walk domain and the nanoparticle is moving to a new randomly chosen position. The new position is accepted with a probability exp(−ΔE/kT), where ΔE is the electrostatic energy difference between the two positions, k is the Boltzmann's constant and T is the temperature. Periodic boundary conditions are applied and in case of collision with a fiber the displacement is rejected.