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Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Translocation of a heterogeneous polymer
Stephen Mirigian1, Yanbo Wang, Murugappan Muthukumar
1Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.
The Journal of Chemical Physics
|August 18, 2012
Summary
We studied how partially charged polymer chains move through pores, finding that charge distribution significantly impacts translocation speed. A surprising threshold charge fraction exists for diblock copolymers, beyond which translocation success rate becomes constant.
Area of Science:
- Polymer physics
- Biophysics
- Statistical mechanics
Background:
- Understanding polymer translocation through nanopores is crucial for applications like DNA sequencing and drug delivery.
- The kinetics of polymer translocation are influenced by various factors including pore size, polymer properties, and external fields.
- Heteropolymers, with varying monomer properties, present complex translocation dynamics compared to homogeneous polymers.
Purpose of the Study:
- To investigate the sequence dependence of translocation kinetics for partially charged heteropolymers through a narrow pore.
- To analyze the influence of charge fraction, charge distribution, and electric field on translocation behavior.
- To compare theoretical predictions with Langevin dynamics simulations for accuracy.
Main Methods:
- Theoretical analysis employing exact analytical expressions for passage probability and mean first passage times.
- Langevin dynamics simulations to model the translocation process.
- Investigation of different boundary conditions (reflecting/absorbing and absorbing/absorbing).
Main Results:
- Analytical expressions derived for passage probability and mean first passage times.
- Excellent qualitative and good quantitative agreement between theoretical models and simulation results.
- Identified a threshold charge fraction for diblock copolymers where translocation success rate plateaus.
- Observed non-monotonic behavior in mean successful translocation time with increasing charged block length.
- Demonstrated that finer charge distribution along the backbone significantly reduces mean translocation time.
Conclusions:
- The translocation kinetics of partially charged heteropolymers are highly sensitive to charge fraction and distribution.
- A critical charge fraction exists for diblock copolymers, simplifying translocation success rate prediction.
- Optimal charge block lengths can minimize or maximize translocation rates, offering control over the process.
- Finer charge distribution is a key factor in accelerating heteropolymer translocation, regardless of total charge.
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