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Related Experiment Video

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High Resolution Physical Characterization of Single Metallic Nanoparticles

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Published on: June 28, 2019

Polymer capture by α-hemolysin pore upon salt concentration gradient.

Byoung-jin Jeon¹, Murugappan Muthukumar¹

¹Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.

The Journal of Chemical Physics

|January 14, 2014

Summary

We studied how sodium poly(styrene sulfonate) molecules are captured by α-hemolysin protein pores. Molecule capture rates depend on pH and salt concentration, showing complex interactions that influence polymer translocation.

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Area of Science:

Biophysics
Nanotechnology
Polymer Science

Background:

Understanding polymer translocation through nanopores is crucial for applications like DNA sequencing and drug delivery.
The α-hemolysin protein pore is a well-established model system for studying molecular transport.
Factors like applied voltage, pH, and salt concentration gradients are known to influence translocation dynamics.

Purpose of the Study:

To investigate the capture rate of single sodium poly(styrene sulfonate) molecules by the α-hemolysin protein pore.
To elucidate the roles of electrostatic interactions and salt concentration gradients in polymer capture.
To analyze how varying pH and applied voltage affects the coupling between pore-polymer interactions and translocation drift.

Main Methods:

Single-molecule experiments measuring the capture rate of sodium poly(styrene sulfonate) by α-hemolysin.
Systematic variation of applied voltage, pH, and salt concentration asymmetry across the pore.
Analysis of polymer capture rate dependence on these experimental parameters.

Main Results:

Electrostatic interactions between the polyelectrolyte and protein pore significantly impact capture rate, alongside electrolyte concentration gradient effects.
At higher pH (repulsive interaction), an antagonistic coupling leads to non-monotonic capture rate dependence on donor salt concentration.
At lower pH (attractive interaction), synergy with salt gradient drift results in monotonic capture rate dependence on donor salt concentration.

Conclusions:

The interplay between electrostatic forces and salt concentration gradients dictates polymer capture dynamics in nanopores.
Antagonistic and synergistic coupling regimes were identified, influencing the capture rate's dependence on salt concentration.
Applied electric field strength can modulate the coupling between pore-polymer interactions and drift, affecting translocation.