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The effect of translocating cylindrical particles on the ionic current through a nanopore
Hui Liu1, Shizhi Qian, Haim H Bau
1Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Biophysical Journal
|December 5, 2006
Summary
This study investigates electric field-driven particle movement through nanopores. The multi-ion model accurately predicts ionic current changes, unlike simplified models, especially for large electric double layers.
Area of Science:
- Nanotechnology
- Physical Chemistry
- Biophysics
Background:
- Understanding particle translocation through nanopores is crucial for applications like DNA sequencing and drug delivery.
- Existing simplified models (Poisson-Boltzmann, Smoluchowski) have limitations in accurately predicting behavior under various conditions.
Purpose of the Study:
- To theoretically investigate electric field-induced translocation of cylindrical particles through nanopores.
- To compare the accuracy of a multi-ion model (MIM) against simplified Poisson-Boltzmann (PBM) and Smoluchowski's slip velocity (SVM) models.
- To delineate the limitations of PBM and SVM models.
Main Methods:
- Simultaneous solution of coupled Nernst-Planck equations (for ion concentration) and Stokes equation (for flow field) using the multi-ion model (MIM).
- Computation of concentration fields, ionic current, and particle velocity.
- Comparison of MIM predictions with PBM and SVM models and experimental data.
Main Results:
- The MIM predicts that translocating particles can either block or enhance ionic current, depending on solution concentration, aligning with experimental observations.
- Discrepancies between MIM, PBM, and SVM predictions arise when the electric double layer thickness is large.
- The study identifies and explains the limitations of the PBM and SVM models.
Conclusions:
- The multi-ion model (MIM) provides a more accurate theoretical framework for studying electric field-induced particle translocation through nanopores compared to simplified models.
- The findings help explain experimental data, particularly for DNA molecule translocation, and highlight the importance of considering ion-concentration effects.
- Accurate modeling is essential for optimizing nanopore-based technologies.
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