Finite-size effects in microrheology.

We propose a model to explain finite-size effects in intracellular microrheology observed in experiments. The constrained dynamics of the particles in the intracellular medium, treated as a viscoelastic medium, is described by means of a diffusion equation in which interactions of the particles with the cytoskeleton are modeled by a harmonic force. The model reproduces the observed power law behavior of the mean square displacement in which the exponent depends on the ratio between particle-to-cytoskeleton-network sizes.