Different anomalous diffusion regimes measured in the dynamics of tracer particles in actin networks

Abstract

It was previously believed that diffusion of a tracer particle in a viscoelastic material should be of the fractional Brownian motion (fBm) type. This is due to the long-term memory in the response of such materials to mechanical perturbations. Surprisingly, the diffusion of a tracer particle in a network of a purified protein, actin, was found to conform to the continuous time random walk (CTRW) type in one study that focused on the ensemble average characteristics. Here, we analyze the dynamics of two differently sized tracer particles in actin networks of different mesh sizes. We find that the ratio of tracer particle size to the characteristic length scale of a bio-polymer network plays a crucial role in determining the type of diffusion the particle performs. We find that the tracer particle diffusion has features of fBm when the particle is large compared to the mesh size, of normal diffusion when the particle is much smaller than the mesh size, and of CTRW in between these two limits. Based on our findings, we propose and verify numerically a new model for the tracer particle's motion in all regimes. Our model suggests that diffusion in actin networks consists of fBm of the tracer particle coupled with occasional caging events with power-law-distributed escape times.

9 pages, 8 figures

References in corpus (13)

• Probing microscopic origins of confined subdiffusion by first-passage observables
• Anomalous hydrodynamic interaction in a quasi-two-dimensional suspension
• Mechanics of bundled semiflexible polymer networks
• Large work extraction and the Landauer limit in a continuous Maxwell demon
• Non-universal tracer diffusion in crowded media of non-inert obstacles
• Measurement of Anomalous Diffusion Using Recurrent Neural Networks
• Visualizing the strain field in semiflexible polymer networks: strain fluctuations and nonlinear rheology of F-actin gels
• Collective dynamics effect transient subdiffusion of inert tracers in gel networks
• Fractional Brownian motion in a finite interval: correlations effect depletion or accretion zones of particles near boundaries
• A Random Walk to a Non-Ergodic Equilibrium Concept
• Anomalous diffusion for active Brownian particles cross-linked to a networked polymer: Langevin dynamics simulation and theory
• Response of a polymer network to the motion of a rigid sphere
• Identification of Anomalous Diffusion Sources by Unsupervised Learning

Cited by in corpus (6)

• Aging power spectrum of membrane protein transport and other subordinated random walks
• Active diffusion of self-propelled particles in flexible polymer networks
• Simultaneous nanorheometry and nanothermometry using intracellular diamond quantum sensors
• Dynamics of self-propelled tracer particles inside a polymer network
• Time-fractional Caputo derivative versus other integro-differential operators in generalized Fokker-Planck and generalized Langevin equations
• Multifractional Brownian motion with telegraphic, stochastically varying exponent