Ejection dynamics of a ring polymer out of a nanochannel

TL;DR

This study analyzes the ejection dynamics of ring polymers from nanochannels, revealing two regimes based on chain length, with implications for biological processes like chromosome segregation.

Contribution

It combines theoretical analysis and simulations to uncover how ring polymer ejection speed varies with chain length relative to a critical threshold.

Findings

Long chains eject faster due to entropic pulling.

Short chains take longer to eject because of diffusion distance.

Ejection dynamics depend on chain length relative to channel occupancy.

Abstract

We investigate the ejection dynamics of a ring polymer out of a cylindrical nanochannel using both theoretical analysis and three dimensional Langevin dynamics simulations. The ejection dynamics for ring polymers shows two regimes like for linear polymers, depending on the relative length of the chain compared with the channel. For long chains with length $N$ larger than the critical chain length $N_{c}$, at which the chain just fully occupies the nanochannel, the ejection for ring polymers is faster compared with linear chains of identical length due to a larger entropic pulling force; while for short chains ($N<N_c$), it takes longer time for ring polymers to eject out of the channel due to a longer distance to be diffused to reach the exit of the channel before experiencing the entropic pulling force. These results can help understand many biological processes, such as bacterial chromosome segregation.