Polymer translocation through a nanopore under an applied external field.

Area of Science:

• Soft Matter Physics
• Polymer Physics
• Nanotechnology

Background:

• Polymer translocation through nanopores is crucial for biological processes and nanotechnology applications.
• Understanding the factors influencing translocation dynamics, such as external fields and polymer/pore dimensions, is essential.

Purpose of the Study:

• To investigate the dynamics of polymer translocation through a nanopore under an externally applied field.
• To analyze the influence of field strength (E), chain length (N), and pore length (L) on forced translocation time (tau).

Main Methods:

• Utilized the two-dimensional fluctuating bond model.
• Employed single-segment Monte Carlo moves for simulations.
• Focused on analyzing scaling relationships between translocation time, velocity, and system parameters.

Main Results:

• Discovered a crossover scaling for translocation time (tau) with chain length (N): tau ~ N^(2*nu) for short chains and tau ~ N^(1+nu) for long chains, where nu is the Flory exponent.
• Observed a crossover in translocation velocity (v) from v ~ N^(-nu) to v ~ N^(-1) for longer polymers, attributed to increased segment density near the pore exit.
• Found no clear scaling of tau with N for long pores (Rg || < L), but recovered the asymptotic scaling tau ~ N^(1+nu) for large N, with tau largely independent of L in this regime.

Conclusions:

• The study reveals complex scaling behaviors in polymer translocation dynamics driven by external fields.
• Chain length and pore geometry significantly impact translocation time and velocity, with segment-pore interactions playing a key role.
• The findings provide insights into controlling and optimizing polymer translocation processes in confined geometries.