Tracer diffusion in a sea of polymers with binding zones: mobile vs frozen traps

Abstract

We use molecular dynamics simulations to investigate the tracer diffusion in a sea of polymers with specific binding zones for the tracer. These binding zones act as traps. Our simulations show that the tracer can undergo normal yet non-Gaussian diffusion under certain circumstances, e.g, when the polymers with traps are frozen in space and the volume fraction and the binding strength of the traps are moderate. In this case, as the tracer moves, it experiences a heterogeneous environment and exhibits confined continuous time random walk (CTRW) like motion resulting a non-Gaussian behavior. Also the long time dynamics becomes subdiffusive as the number or the binding strength of the traps increases. However, if the polymers are mobile then the tracer dynamics is Gaussian but could be normal or subdiffusive depending on the number and the binding strength of the traps. In addition, with increasing binding strength and the number of the polymer traps, the probability of the tracer being trapped increases. On the other hand, removing the binding zones does not result trapping, even at comparatively high crowding. Our simulations also show that the trapping probability increases with the increasing size of the tracer and for a bigger tracer with the frozen polymer background the dynamics is only weakly non-Gaussian but highly subdiffusive. Our observations are in the same spirit as found in many recent experiments on tracer diffusion in polymeric materials and questions the validity of Gaussian theory to describe diffusion in crowded environment in general.

References in corpus (7)

• "Diffusing diffusivity": A model for anomalous and "anomalous yet Brownian" diffusion
• Non-universal tracer diffusion in crowded media of non-inert obstacles
• Kinetics of polymer looping with macromolecular crowding: effects of volume fraction and crowder size
• Dimensional Study of the Caging Order Parameter at the Glass Transition
• Anomalous diffusion in time-fluctuating non-stationary diffusivity landscapes
• Simulational study of anomalous tracer diffusion in hydrogels
• Dynamics of end to end loop formation for an isolated chain in viscoelastic fluid

Cited by in corpus (16)

• Diffusion-limited reactions in dynamic heterogeneous media
• Escape of a passive particle from activity-induced energy landscape: Emergence of slow and fast effective diffusion
• Test of the diffusing-diffusivity mechanism using near-wall colloidal dynamics
• Translational and rotational dynamics of a self-propelled Janus probe in crowded environments
• Exact extreme, order and sum statistics in a class of strongly correlated system
• First-encounter time of two diffusing particles in confinement
• Ergodic property of Langevin systems with superstatistical, uncorrelated or correlated diffusivity
• Ergodic property of random diffusivity system with trapping events
• A mini-review of the diffusion dynamics of DNA-binding proteins: Experiments and models
• Extended Poisson-Kac theory: A unifying framework for stochastic processes with finite propagation velocity
• Transport of a self-propelled tracer through a hairy cylindrical channel: interplay of stickiness and activity
• Motion of an active particle with dynamical disorder
• Novel anomalous diffusion phenomena of underdamped Langevin equation with random parameters
• First-encounter time of two diffusing particles in two- and three-dimensional confinement
• Model studies on motion of respiratory droplets driven through a face mask
• Tracer dynamics in dense soft-colloidal suspensions: From free diffusion to hopping