Facilitation of polymer looping and giant polymer diffusivity in crowded solutions of active particles

TL;DR

This study investigates how active particles influence polymer dynamics, showing enhanced looping and diffusivity, with implications for biological and colloidal systems.

Contribution

It reveals the effects of active particles on polymer conformations, looping kinetics, and diffusivity, providing detailed simulation data across various activity levels.

Findings

Active particles extend flexible polymers and compact semiflexible ones.

Higher activity increases effective temperature, facilitating polymer looping.

Giant diffusivity enhancement observed for polymers in active baths.

Abstract

We study the dynamics of polymer chains in a bath of self-propelled particles (SPP) by extensive Langevin dynamics simulations in a two dimensional system. Specifically, we analyse the polymer looping properties versus the SPP activity and investigate how the presence of the active particles alters the chain conformational statistics. We find that SPPs tend to extend flexible polymer chains while they rather compactify stiffer semiflexible polymers, in agreement with previous results. Here we show that larger activities of SPPs yield a higher effective temperature of the bath and thus facilitate looping kinetics of a passive polymer chain. We explicitly compute the looping probability and looping time in a wide range of the model parameters. We also analyse the motion of a monomeric tracer particle and the polymer's centre of mass in the presence of the active particles in terms of the time averaged mean squared displacement, revealing a giant diffusivity enhancement for the polymer chain via SPP pooling. Our results are applicable to rationalising the dimensions and looping kinetics of biopolymers at constantly fluctuating and often actively driven conditions inside biological cells or suspensions of active colloidal particles or bacteria cells.