Semiflexibility speeds up the translocation of multiple polymers in nanopores

Abstract

The process of polymer translocation (PT) through narrow pores is essential for a number of biological systems. Here, we investigate the unforced PT of a single and of multiple polymers through a pore constructed in two dimensions using Langevin-dynamics simulations within a coarse-grained bead–spring model. We aim at determining under which conditions the “stacking” of multiple polymers inside the pore can facilitate their cooperative PT. The results show that increasing the bending stiffness κ of a single polymer typically slows down the PT process by reducing the configurational freedom and by inhibiting the propagation of tension along the chain. In contrast, when two polymers occupy the pore simultaneously, an increase in their bending stiffness can speed up their PT process. Two flexible polymers translocate faster than a single flexible chain due to “entropic pushing,” while two semiflexible chains increasingly prefer the same-side PT as their stiffness increases. In “mixed” situations of a simultaneous PT of a flexible and a semiflexible polymer, the latter consistently translocates faster due to reduced entropic trapping and more efficient tension propagation. These findings demonstrate counterintuitively that the bending stiffness, which typically limits the single-PT dynamics, can enhance the cooperative transport through a pore in multiple-chain scenarios. This can provide new insights regarding the properties of PT in a number of systems featuring, e.g., biological channels or synthetic nanopores.