Pulling a folded polymer through a nanopore.

Area of Science:

• Polymer Physics
• Nanotechnology
• Biophysics

Background:

• Polymer translocation through nanopores is crucial for biological processes and nanotechnology applications.
• Understanding the dynamics of folded polymers during translocation presents unique challenges compared to linear polymers.

Purpose of the Study:

• To generalize existing theories for polymer translocation to accommodate folded polymer structures.
• To analyze the translocation dynamics of a folded linear polymer pulled through a nanopore by an external force.

Main Methods:

• Generalization of the iso-flux tension propagation theory.
• Benchmarking theoretical predictions with extensive molecular dynamics (MD) simulations.
• Analytical derivation of equations of motion based on equal monomer flux assumption.

Main Results:

• The translocation process is characterized by two distinct stages: coupled dynamics of both branches and, if unequal, sequential translocation of the shorter branch.
• The theory accurately predicts the dynamics, validated by MD simulations.
• Detailed characterization of translocation dynamics through average waiting time and its scaling form.

Conclusions:

• The generalized theory provides a robust framework for understanding folded polymer translocation.
• The two-stage model accurately describes the observed dynamics, particularly for polymers with unequal branches.
• This work advances the understanding of polymer behavior in confined geometries, with implications for nanopore sensing and DNA manipulation.