Active diffusion of self-propelled particles in flexible polymer networks

Abstract

Biopolymer networks having a meshwork topology, e.g., extracellular matrix and mucus gels, are ubiquitous. It is an open question to understand how self-propelled agents such as Janus colloidal particles diffuse through such a biopolymer network. Here, we computationally explore this issue in-depth by explicitly modeling three-dimensional biopolymer networks and performing Langevin dynamics simulations of active diffusion of the self-propelled tracers therein. We show that the active tracer performs distinct diffusion dynamics depending on the mesh-to-particle size and Péclet number (Pe). When the particle is smaller than the mesh size, it moves as if in free space with a decreased mobility depending on the polymer occupation density and Pe. However, when the particle size is increased to be comparable to the mesh size, the active particles explore the polymer network using the trapped-and-hopping mechanism. We study the trapped time distribution, flight length distribution, the mean-squared displacement, and the long-time diffusivity at varying Pe. If the particle is larger than the mesh, it captures the collective viscoelastic dynamics from the polymer network at short times and the simple diffusion of the total system at large times. Finally, we discuss the scaling behavior of the long-time diffusivity with Pe, where we find a range of Pe that yields a nontrivial power law. The latter turns out to arise from a large fluctuation of trapped, activated tracers in conjugation with responsive polymer networks.

12 pages, 5 main figures & 4 supplementary figures

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Cited by in corpus (9)

• Dynamics of self-propelled tracer particles inside a polymer network
• Nonequilibrium diffusion of active particles bound to a semi-flexible polymer network: simulations and fractional Langevin equation
• Dynamics of a spherical self-propelled tracer in a polymeric medium: interplay of self-propulsion, stickiness, and crowding
• Brownian particles in periodic potentials: coarse-graining versus fine structure
• Active doping controls the mode of failure in dense colloidal gels
• Diffusion dynamics of an overdamped active ellipsoidal particle in two dimensions
• Stochastic resetting in a nonequilibrium environment
• Self-organised structures in mixed active-passive suspensions due to hydrodynamic interactions
• Nonequilibrium friction and free energy estimates for kinetic coarse-graining -- Driven particles in responsive media