1
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Rao YF, Sun LZ, Luo MB. Na +-Mg 2+ ion effects on conformation and translocation dynamics of single-stranded RNA: Cooperation and competition. Int J Biol Macromol 2024; 267:131273. [PMID: 38569994 DOI: 10.1016/j.ijbiomac.2024.131273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/20/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024]
Abstract
The nanopore-based translocation of a single-stranded RNA (ssRNA) in mixed salt solution has garnered increasing interest for its biological and technological significance. However, it is challenging to comprehensively understand the effects of the mixed ion species on the translocation dynamics due to their cooperation and competition, which can be directly reflected by the ion screening and neutralizing effects, respectively. In this study, Langevin dynamics simulation is employed to investigate the properties of ssRNA conformation and translocation in mixed Na+-Mg2+ ion environments. Simulation results reveal that the ion screening effect dominates the change in the ssRNA conformational size, the ion neutralizing effect controls the capture rate of the ssRNA by the nanopore, and both of them take charge of the different changes in translocation time of the ssRNA under various mixed ion environments. Under high Na+ ion concentration, as Mg2+ concentration increases, the ion neutralizing effect strengthens, weakening the driving force inside the nanopore, leading to longer translocation time. Conversely, at low Na+ concentration, an increase in Mg2+ concentration enhances the ion screening effect, aiding in faster translocation. Furthermore, these simulation results will be explained by quantitative analysis, advancing a deeper understanding of the complicated effects of the mixed Na+-Mg2+ ions.
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Affiliation(s)
- Yi-Fan Rao
- School of Physics, Zhejiang University, Hangzhou 310027, China; Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Li-Zhen Sun
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China.
| | - Meng-Bo Luo
- School of Physics, Zhejiang University, Hangzhou 310027, China.
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2
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Upadhyay G, Kapri R, Chaudhuri A. Homopolymer and heteropolymer translocation through patterned pores under fluctuating forces. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:23. [PMID: 38573533 DOI: 10.1140/epje/s10189-024-00417-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/18/2024] [Indexed: 04/05/2024]
Abstract
We investigate the translocation of a semiflexible polymer through extended patterned pores using Langevin dynamics simulations, specifically focusing on the influence of a time-dependent driving force. Our findings reveal that, akin to its flexible counterpart, a rigid chain-like molecule translocates faster when subjected to an oscillating force than a constant force of equivalent average magnitude. The enhanced translocation is strongly correlated with the stiffness of the polymer and the stickiness of the pores. The arrangement of the pores plays a pivotal role in translocation dynamics, deeply influenced by the interplay between polymer stiffness and pore-polymer interactions. For heterogeneous polymers with periodically varying stiffness, the oscillating force introduces significant variations in the translocation time distributions based on segment sizes and orientations. On the basis of these insights, we propose a sequencing approach that harnesses distinct pore surface properties that are capable of accurately predicting sequences in heteropolymers with diverse bending rigidities.
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Affiliation(s)
- Gokul Upadhyay
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, 140306, India
| | - Rajeev Kapri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, 140306, India
| | - Abhishek Chaudhuri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli, 140306, India.
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3
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Upadhyay G, Kapri R, Chaudhuri A. Gain reversal in the translocation dynamics of a semiflexible polymer through a flickering pore. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:185101. [PMID: 38262064 DOI: 10.1088/1361-648x/ad21a9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/23/2024] [Indexed: 01/25/2024]
Abstract
We study the driven translocation of a semiflexible polymer through an attractive extended pore with a periodically oscillating width. Similar to its flexible counterpart, a stiff polymer translocates through an oscillating pore more quickly than a static pore whose width is equal to the oscillating pore's mean width. This efficiency quantified as a gain in the translocation time, highlights a considerable dependence of the translocation dynamics on the stiffness of the polymer and the attractive nature of the pore. The gain characteristics for various polymer stiffness exhibit a trend reversal when the stickiness of the pore is changed. The gain reduces with increasing stiffness for a lower attractive strength of the pore, whereas it increases with increasing stiffness for higher attractive strengths. Such a dependence leads to the possibility of a high degree of robust selectivity in the translocation process.
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Affiliation(s)
- Gokul Upadhyay
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
| | - Rajeev Kapri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
| | - Abhishek Chaudhuri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
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4
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Tan F, Wang J, Yan R, Zhao N. Forced and spontaneous translocation dynamics of a semiflexible active polymer in two dimensions. SOFT MATTER 2024; 20:1120-1132. [PMID: 38224190 DOI: 10.1039/d3sm01409f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Polymer translocation is a fundamental topic in non-equilibrium physics and is crucially important to many biological processes in life. In the present work, we adopt two-dimensional Langevin dynamics simulations to study the forced and spontaneous translocation dynamics of an active filament. The influence of polymer stiffness on the underlying dynamics is explicitly analyzed. For the forced translocation, the results show a robust stiffness-induced inhibition, and the translocation time exhibits a dual-exponent scaling relationship with the bending modulus. Tension propagation (TP) is also examined, where we find prominent modifications in terms of both activity and stiffness. For spontaneous translocation into a pure solvent, the translocation time is almost independent of the polymer stiffness. However, when the polymer is translocated into a porous medium, an intriguing non-monotonic alteration of translocation time with increasing chain stiffness is demonstrated. The semiflexible chain is beneficial for translocation while the rigid chain is not conducive. Stiffness regulation on the diffusion dynamics of the polymer in porous media shows a consistent scenario. The interplay of activity, stiffness, and porous crowding provides a new mechanism for understanding the non-trivial translocation dynamics of an active filament in complex environments.
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Affiliation(s)
- Fei Tan
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Jingli Wang
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Ran Yan
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu 610064, China.
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5
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Tan F, Yan R, Zhao C, Zhao N. Translocation Dynamics of an Active Filament through a Long-Length Scale Channel. J Phys Chem B 2023; 127:8603-8615. [PMID: 37782905 DOI: 10.1021/acs.jpcb.3c04250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Active filament translocation through a confined space is crucial for diverse biological processes. By using Langevin dynamics simulations, we investigate the translocation dynamics of an axially self-propelled chain through a channel. First, results show a suggestive reciprocal scaling of translocation time versus active force. Second, in the case of a long channel, we demonstrate a very intriguing nonmonotonic change of translocation time with increasing channel width. The driving force shows a similar trend, providing a consistent picture to understand the unexpected channel width effect. In particular, in a moderately broad channel, the disordered chain conformation results in a loss of driving force and thus inhibits translocation dynamics. Chain adsorption might occur in a wide channel, which accounts for a facilitated translocation. Lastly, we connect the translocation process to tension propagation (TP). A modified TP picture is proposed to interpret the waiting time distribution. Our work highlights the new phenomenology owing to the crucial interplay of activity and spacial confinement, which drives the translocation dynamics, going beyond the traditional entropic barrier scenario.
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Affiliation(s)
- Fei Tan
- College of Chemistry, Sichuan University, Chengdu 610065, China
| | - Ran Yan
- College of Chemistry, Sichuan University, Chengdu 610065, China
| | - Chaonan Zhao
- College of Chemistry, Sichuan University, Chengdu 610065, China
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu 610065, China
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6
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Singh SL, Chauhan K, Bharadwaj AS, Kishore V, Laux P, Luch A, Singh AV. Polymer Translocation and Nanopore Sequencing: A Review of Advances and Challenges. Int J Mol Sci 2023; 24:6153. [PMID: 37047125 PMCID: PMC10094227 DOI: 10.3390/ijms24076153] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/01/2023] [Accepted: 02/28/2023] [Indexed: 03/31/2023] Open
Abstract
Various biological processes involve the translocation of macromolecules across nanopores; these pores are basically protein channels embedded in membranes. Understanding the mechanism of translocation is crucial to a range of technological applications, including DNA sequencing, single molecule detection, and controlled drug delivery. In this spirit, numerous efforts have been made to develop polymer translocation-based sequencing devices, these efforts include findings and insights from theoretical modeling, simulations, and experimental studies. As much as the past and ongoing studies have added to the knowledge, the practical realization of low-cost, high-throughput sequencing devices, however, has still not been realized. There are challenges, the foremost of which is controlling the speed of translocation at the single monomer level, which remain to be addressed in order to use polymer translocation-based methods for sensing applications. In this article, we review the recent studies aimed at developing control over the dynamics of polymer translocation through nanopores.
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Affiliation(s)
- Swarn Lata Singh
- Department of Physics, Mahila Mahavidyalaya (MMV), Banaras Hindu University, Varanasi 221005, UP, India
| | - Keerti Chauhan
- Department of Physics, Banaras Hindu University, Varanasi 221005, UP, India
| | - Atul S. Bharadwaj
- Department of Physics, CMP Degree College, University of Allahabad, Prayagraj 211002, UP, India
| | - Vimal Kishore
- Department of Physics, Banaras Hindu University, Varanasi 221005, UP, India
| | - Peter Laux
- Department of Chemical and Product Safety, German Federal Institute of Risk Assessment (BfR) Maxdohrnstrasse 8-10, 10589 Berlin, Germany
| | - Andreas Luch
- Department of Chemical and Product Safety, German Federal Institute of Risk Assessment (BfR) Maxdohrnstrasse 8-10, 10589 Berlin, Germany
| | - Ajay Vikram Singh
- Department of Chemical and Product Safety, German Federal Institute of Risk Assessment (BfR) Maxdohrnstrasse 8-10, 10589 Berlin, Germany
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7
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Lu LW, Wang ZH, Shi AC, Lu YY, An LJ. Polymer Translocation. CHINESE JOURNAL OF POLYMER SCIENCE 2023. [DOI: 10.1007/s10118-023-2975-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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8
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Sharma A, Kapri R, Chaudhuri A. Driven translocation of a semiflexible polymer through a conical channel in the presence of attractive surface interactions. Sci Rep 2022; 12:19081. [PMID: 36351960 PMCID: PMC9646819 DOI: 10.1038/s41598-022-21845-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 10/04/2022] [Indexed: 11/11/2022] Open
Abstract
We study the translocation of a semiflexible polymer through a conical channel with attractive surface interactions and a driving force which varies spatially inside the channel. Using the results of the translocation dynamics of a flexible polymer through an extended channel as control, we first show that the asymmetric shape of the channel gives rise to non-monotonic features in the total translocation time as a function of the apex angle of the channel. The waiting time distributions of individual monomer beads inside the channel show unique features strongly dependent on the driving force and the surface interactions. Polymer stiffness results in longer translocation times for all angles of the channel. Further, non-monotonic features in the translocation time as a function of the channel angle changes substantially as the polymer becomes stiffer, which is reflected in the changing features of the waiting time distributions. We construct a free energy description of the system incorporating entropic and energetic contributions in the low force regime to explain the simulation results.
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Affiliation(s)
- Andri Sharma
- grid.458435.b0000 0004 0406 1521Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Mohali, 140306 Punjab India
| | - Rajeev Kapri
- grid.458435.b0000 0004 0406 1521Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Mohali, 140306 Punjab India
| | - Abhishek Chaudhuri
- grid.458435.b0000 0004 0406 1521Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Mohali, 140306 Punjab India
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9
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Fiasconaro A, Díez-Señorans G, Falo F. End-pulled polymer translocation through a many-body flexible pore. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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10
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Abstract
Despite an extensive theoretical and numerical background, the translocation ratchet mechanism, which is fundamental for the transmembrane transport of biomolecules, has never been experimentally reproduced at the nanoscale. Only the Sec61 and bacterial type IV pilus pores were experimentally shown to exhibit a translocation ratchet mechanism. Here we designed a synthetic translocation ratchet and quantified its efficiency as a nanopump. We measured the translocation frequency of DNA molecules through nanoporous membranes and showed that polycations at the trans side accelerated the translocation in a ratchet-like fashion. We investigated the ratchet efficiency according to geometrical and kinetic parameters and observed the ratchet to be only dependent on the size of the DNA molecule with a power law [Formula: see text]. A threshold length of 3 kbp was observed, below which the ratchet did not operate. We interpreted this threshold in a DNA looping model, which quantitatively explained our results.
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11
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Sun LZ, Qian JL, Cai P, Hu HX, Xu X, Luo MB. Mg2+ effects on the single-stranded DNA conformations and nanopore translocation dynamics. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.124895] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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12
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Effect of Solvent Viscosity on the Driven Translocation of Charged Polymers through Nanopores. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-022-2696-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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13
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Abstract
The force- and flow-induced translocation processes of linear and ring polymers are studied using a combination of multiparticle collision dynamics and molecular dynamics, focusing on the behavior of the polymer translocation time. We compare the force- and flow-induced translocations of linear and ring polymers. It is found that when the translocation time (τ*) is characterized by scaling exponents, δ, δ', and α, via the relations τ* ∼ fδNα and τ* ∼ Jδ'Nα, the scaling exponents are not constants. For long chains tested, α = 1.0 for both force- and flow-induced translocations. The difference between the force- and flow-induced translocations stems from different monomer crowding effects due to distinct flow patterns outside the channel. Furthermore, general relations for polymer translocation time are derived for these two translocation processes, which are in good agreement with the simulation results. Our results provide clear molecular pictures for the force- and flow-induced translocations, which shed light on the understanding of translocation dynamics and provide guidance for practical applications such as molecular sequencing and ultrafiltration.
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Affiliation(s)
- Yuyuan Lu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Zhenhua Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
| | - Lijia An
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - An-Chang Shi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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14
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Tan F, Chen Y, Zhao N. Effects of active crowder size and activity-crowding coupling on polymer translocation. SOFT MATTER 2021; 17:1940-1954. [PMID: 33427276 DOI: 10.1039/d0sm01906b] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Polymer translocation in complex environments is crucially important to many biological processes in life. In the present work, we adopted two-dimensional Langevin dynamics simulations to study the forced and unbiased polymer translocation dynamics in active and crowded media. The translocation time and probability are analyzed in terms of active force Fa, volume fraction φ and also the crowder size. The non-trivial active crowder size effect and activity-crowding coupling effect as well as the novel mechanism of unbiased translocation between two active environments with different active particle sizes are clarified. Firstly, for forced translocation, we reveal an intriguing non-monotonic dependence of the translocation time on the crowder size in the case of large activity. In particular, crowders of intermediate size similar to the polymer segment are proven to be the most favorable for translocation. Moreover, a facilitation-inhibition crossover of the translocation time with increasing volume fraction is observed, indicating a crucial activity-crowding coupling effect. Secondly, for unbiased translocation driven by different active crowder sizes, the translocation probability demonstrates a novel turnover phenomenon, implying the appearance of an opposite directional preference as the active force exceeds a critical value. The translocation time in both directions decreases monotonically with the active force. The asymmetric activity effect together with the entropic driving scenario provides a reasonable picture for the peculiar behavior observed in unbiased translocation.
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Affiliation(s)
- Fei Tan
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Ying Chen
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu 610064, China.
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15
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Sun LZ, Cao WP, Wang CH, Xu X. The translocation dynamics of the polymer through a conical pore: Non-stuck, weak-stuck, and strong-stuck modes. J Chem Phys 2021; 154:054903. [PMID: 33557527 DOI: 10.1063/5.0033689] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The external voltage-driven polymer translocation through a conical pore (with a large opening at the entry and a small tip at the exit) is studied by using the Langevin dynamics simulation in this paper. The entire translocation process is divided into an approaching stage and a threading stage. First, the approaching stage starts from the polymer entering the large opening and ends up at a terminal monomer reaching the pore tip. In this stage, the polymer will undergo the conformation adjustment to fit the narrowed cross-sectional area of the pore, leading to three approaching modes: the non-stuck mode with a terminal monomer arriving at the pore tip smoothly, the weak-stuck mode for the polymer stuck inside the pore for a short duration with minor conformational adjustments, and the strong-stuck mode with major conformational changes and a long duration. The approaching times (the duration of the approaching stage) of the three approaching modes show different behavior as a function of the pore apex angle. Second, the threading stage describes that the polymer threads through the pore tip with a linear fashion. In this stage, an increase in the apex angle causes the reduction of the threading time (the duration of the threading stage) due to the increase in the driving force with the apex angle at the tip. Moreover, we also find that with the increase in the apex angle or the polymer length, the polymer threading dynamics will change from the quasi-equilibrium state to the non-equilibrium state.
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Affiliation(s)
- Li-Zhen Sun
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Wei-Ping Cao
- Institute of Optoelectronic Technology, Lishui University, Lishui 323000, China
| | - Chang-Hui Wang
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Xiaojun Xu
- Institute of Bioinformatics and Medical Engineering, Jiangsu University of Technology, Changzhou 213001, China
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16
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Ghosh B, Sarabadani J, Chaudhury S, Ala-Nissila T. Pulling a folded polymer through a nanopore. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:015101. [PMID: 32906093 DOI: 10.1088/1361-648x/abb687] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the translocation dynamics of a folded linear polymer which is pulled through a nanopore by an external force. To this end, we generalize the iso-flux tension propagation theory for end-pulled polymer translocation to include the case of two segments of the folded polymer traversing simultaneously trough the pore. Our theory is extensively benchmarked with corresponding molecular dynamics (MD) simulations. The translocation process for a folded polymer can be divided into two main stages. In the first stage, both branches are traversing the pore and their dynamics is coupled. If the branches are not of equal length, there is a second stage where translocation of the shorter branch has been completed. Using the assumption of equal monomer flux of both branches confirmed by MD simulations, we analytically derive the equations of motion for both branches and characterize the translocation dynamics in detail from the average waiting time and its scaling form.
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Affiliation(s)
- Bappa Ghosh
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - Jalal Sarabadani
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), 19395-5531, Tehran, Iran
| | - Srabanti Chaudhury
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, Maharashtra, India
| | - Tapio Ala-Nissila
- Department of Applied Physics and QTF Center of Excellence, Aalto University, PO Box 11000, FI-00076 Aalto, Espoo, Finland
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
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17
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Sarabadani J, Buyukdagli S, Ala-Nissila T. Pulling a DNA molecule through a nanopore embedded in an anionic membrane: tension propagation coupled to electrostatics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:385101. [PMID: 32408289 DOI: 10.1088/1361-648x/ab9342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/14/2020] [Indexed: 06/11/2023]
Abstract
We consider the influence of electrostatic forces on driven translocation dynamics of a flexible polyelectrolyte being pulled through a nanopore by an external force on the head monomer. To this end, we augment the iso-flux tension propagation theory with electrostatics for a negatively charged biopolymer pulled through a nanopore embedded in a similarly charged anionic membrane. We show that in the realistic case of a single-stranded DNA molecule, dilute salt conditions characterized by weak charge screening, and a negatively charged membrane, the translocation dynamics is unexpectedly accelerated despite the presence of large repulsive electrostatic interactions between the polymer coil on thecisside and the charged membrane. This is due to the rapid release of the electrostatic potential energy of the coil during translocation, leading to an effectively attractive force that assists end-driven translocation. The speedup results in non-monotonic polymer length and membrane charge dependence of the exponentαcharacterizing the translocation timeτ∝N0αof the polymer with lengthN0. In the regime of long polymersN0 ≳ 500, the translocation exponent exceeds its upper limitα= 2 previously observed for the same system without electrostatic interactions.
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Affiliation(s)
- Jalal Sarabadani
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), 19395-5531, Tehran, Iran
| | | | - Tapio Ala-Nissila
- Department of Applied Physics and QTF Center of Excellence, Aalto University, P.O. Box 11000, FI-00076 Aalto, Espoo, Finland
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
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18
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Affiliation(s)
- Karthik Nagarajan
- K. Nagarajan, Prof. S. B. ChenDepartment of Chemical & Biomolecular EngineeringNational University of Singapore Singapore 117585 Singapore
| | - Shing Bor Chen
- K. Nagarajan, Prof. S. B. ChenDepartment of Chemical & Biomolecular EngineeringNational University of Singapore Singapore 117585 Singapore
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19
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Qiao L, Slater GW. Capture of rod-like molecules by a nanopore: Defining an "orientational capture radius". J Chem Phys 2020; 152:144902. [PMID: 32295359 DOI: 10.1063/5.0002044] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Both the translational diffusion coefficient D and the electrophoretic mobility μ of a short rod-like molecule (such as dsDNA) that is being pulled toward a nanopore by an electric field should depend on its orientation. Since a charged rod-like molecule tends to orient in the presence of an inhomogeneous electric field, D and μ will change as the molecule approaches the nanopore, and this will impact the capture process. We present a simplified study of this problem using theoretical arguments and Langevin dynamics simulations. In particular, we introduce a new orientational capture radius, which we compare to the capture radius for the equivalent point-like particle, and we discuss the different physical regimes of orientation during capture and the impact of initial orientations on the capture time.
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Affiliation(s)
- Le Qiao
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Gary W Slater
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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20
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Abstract
Although nanopores have shown tremendous promise for use in DNA sequencing, the rate of translocation through most pores studied previously is too rapid for the genetic information to be read accurately. In this study, dissipative particle dynamics simulations were employed to investigate the feasibility of using tortuous nanopores to control the rate of polyelectrolyte translocation. Unlike many previous studies, our simulation method incorporates the effects of hydrodynamic and electrostatic interactions and the spatial variation of electric field strength. The average translocation time, ⟨τ⟩, increases with the pore length and tortuosity but decreases as the pore width increases. For the longest pore investigated, the introduction of tortuosity results in ⟨τ⟩ increasing by as much as 187% as compared to a straight pore. The temporal variation of bond tension indicates that slower translocation in tortuous nanopores is caused by inhibition of tension propagation.
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Affiliation(s)
- Karthik Nagarajan
- Department of Chemical and Biomolecular Engineering , National University of Singapore , 117585 , Singapore
| | - Shing Bor Chen
- Department of Chemical and Biomolecular Engineering , National University of Singapore , 117585 , Singapore
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21
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Ghosh B, Chaudhury S. Translocation Dynamics of an Asymmetrically Charged Polymer through a Pore under the Influence of Different pH Conditions. J Phys Chem B 2019; 123:4318-4323. [DOI: 10.1021/acs.jpcb.8b12301] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Bappa Ghosh
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
| | - Srabanti Chaudhury
- Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, Maharashtra, India
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Abstract
The electric field driven translocation of charged star polymers through a cylindrical nanopore has been studied using dissipative particle dynamics simulations. The critical field strength required to induce translocation depends on both the number of arms and the number of beads per arm. It may therefore be possible to separate star polyelectrolytes of different arm lengths using electric field driven translocation through a nanopore. The average translocation time exhibits nonmonotonic variation with the number of arms for good solvent conditions. During translocation, a star polymer with many arms is stretched along the pore axis to a lesser extent as compared to its linear counterpart. Unlike a linear chain that shows tension propagation with large tensions for bonds about to enter the pore, a star has the tensest bonds closest to the branch point whose connectivity to multiple arms raises difficulty for its entry and passage.
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Affiliation(s)
- Karthik Nagarajan
- Department of Chemical & Biomolecular Engineering , National University of Singapore , 117585 , Singapore
| | - Shing Bor Chen
- Department of Chemical & Biomolecular Engineering , National University of Singapore , 117585 , Singapore
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23
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Buyukdagli S, Sarabadani J, Ala-Nissila T. Theoretical Modeling of Polymer Translocation: From the Electrohydrodynamics of Short Polymers to the Fluctuating Long Polymers. Polymers (Basel) 2019; 11:E118. [PMID: 30960102 PMCID: PMC6401762 DOI: 10.3390/polym11010118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/07/2019] [Accepted: 01/09/2019] [Indexed: 01/08/2023] Open
Abstract
The theoretical formulation of driven polymer translocation through nanopores is complicated by the combination of the pore electrohydrodynamics and the nonequilibrium polymer dynamics originating from the conformational polymer fluctuations. In this review, we discuss the modeling of polymer translocation in the distinct regimes of short and long polymers where these two effects decouple. For the case of short polymers where polymer fluctuations are negligible, we present a stiff polymer model including the details of the electrohydrodynamic forces on the translocating molecule. We first show that the electrohydrodynamic theory can accurately characterize the hydrostatic pressure dependence of the polymer translocation velocity and time in pressure-voltage-driven polymer trapping experiments. Then, we discuss the electrostatic correlation mechanisms responsible for the experimentally observed DNA mobility inversion by added multivalent cations in solid-state pores, and the rapid growth of polymer capture rates by added monovalent salt in α -Hemolysin pores. In the opposite regime of long polymers where polymer fluctuations prevail, we review the iso-flux tension propagation (IFTP) theory, which can characterize the translocation dynamics at the level of single segments. The IFTP theory is valid for a variety of polymer translocation and pulling scenarios. We discuss the predictions of the theory for fully flexible and rodlike pore-driven and end-pulled translocation scenarios, where exact analytic results can be derived for the scaling of the translocation time with chain length and driving force.
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Affiliation(s)
- Sahin Buyukdagli
- Department of Physics, Bilkent University, Ankara 06800, Turkey.
| | - Jalal Sarabadani
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran.
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
| | - Tapio Ala-Nissila
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
- Department of Applied Physics and QTF Center of Excellence, Aalto University School of Science, P.O. Box 11000, FI-00076 Aalto, Espoo, Finland.
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24
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Hsiao PY. Translocation of Charged Polymers through a Nanopore in Monovalent and Divalent Salt Solutions: A Scaling Study Exploring over the Entire Driving Force Regimes. Polymers (Basel) 2018; 10:E1229. [PMID: 30961154 PMCID: PMC6290626 DOI: 10.3390/polym10111229] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 10/31/2018] [Accepted: 11/02/2018] [Indexed: 11/16/2022] Open
Abstract
Langevin dynamics simulations are performed to study polyelectrolytes driven through a nanopore in monovalent and divalent salt solutions. The driving electric field E is applied inside the pore, and the strength is varied to cover the four characteristic force regimes depicted by a rederived scaling theory, namely the unbiased (UB) regime, the weakly-driven (WD) regime, the strongly-driven trumpet (SD(T)) regime and the strongly-driven isoflux (SD(I)) regime. By changing the chain length N, the mean translocation time is studied under the scaling form 〈 τ 〉 ∼ N α E - δ . The exponents α and δ are calculated in each force regime for the two studied salt cases. Both of them are found to vary with E and N and, hence, are not universal in the parameter's space. We further investigate the diffusion behavior of translocation. The subdiffusion exponent γ p is extracted. The three essential exponents ν s , q, z p are then obtained from the simulations. Together with γ p , the validness of the scaling theory is verified. Through a comparison with experiments, the location of a usual experimental condition on the scaling plot is pinpointed.
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Affiliation(s)
- Pai-Yi Hsiao
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
- Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
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25
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de Haan HW, Sean D, Slater GW. Reducing the variance in the translocation times by prestretching the polymer. Phys Rev E 2018; 98:022501. [PMID: 30253469 DOI: 10.1103/physreve.98.022501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Indexed: 11/07/2022]
Abstract
Langevin dynamics simulations of polymer translocation are performed where the polymer is stretched via two opposing forces applied on the first and last monomer before and during translocation. In this setup, polymer translocation is achieved by imposing a bias between the two pulling forces such that there is net displacement towards the trans side. Under the influence of stretching forces, the elongated polymer ensemble contains less variations in conformations compared to an unstretched ensemble. Simulations demonstrate that this reduced spread in initial conformations yields a reduced variation in translocation times relative to the mean translocation time. This effect is explored for different ratios of the amplitude of thermal fluctuations to driving forces to control for the relative influence of the thermal path sampled by the polymer. Since the variance in translocation times is due to contributions coming from sampling both thermal noise and initial conformations, our simulations offer independent control over the two main sources of noise and allow us to shed light on how they both contribute to translocation dynamics. Simulation parameter space corresponding to experimentally relevant conditions is highlighted and shown to correspond to a significant decrease in the spread of translocation times, thus indicating that stretching DNA prior to translocation could assist nanopore-based sequencing and sizing applications.
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Affiliation(s)
- Hendrick W de Haan
- Faculty of Science, University of Ontario Institute of Technology, Oshawa, Ontario, Canada, L1H 7K4
| | - David Sean
- Physics Department, University of Ottawa, Ottawa, Ontario, Canada, K1N 6N5.,Institut für Computerphysik, Universität Stuttgart, 70569 Stuttgart, Germany
| | - Gary W Slater
- Physics Department, University of Ottawa, Ottawa, Ontario, Canada, K1N 6N5
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26
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Sarabadani J, Ala-Nissila T. Theory of pore-driven and end-pulled polymer translocation dynamics through a nanopore: an overview. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:274002. [PMID: 29794332 DOI: 10.1088/1361-648x/aac796] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We review recent progress on the theory of dynamics of polymer translocation through a nanopore based on the iso-flux tension propagation (IFTP) theory. We investigate both pore-driven translocation of flexible and a semi-flexible polymers, and the end-pulled case of flexible chains by means of the IFTP theory and extensive molecular dynamics (MD) simulations. The validity of the IFTP theory can be quantified by the waiting time distributions of the monomers which reveal the details of the dynamics of the translocation process. The IFTP theory allows a parameter-free description of the translocation process and can be used to derive exact analytic scaling forms in the appropriate limits, including the influence due to the pore friction that appears as a finite-size correction to asymptotic scaling. We show that in the case of pore-driven semi-flexible and end-pulled polymer chains the IFTP theory must be augmented with an explicit trans side friction term for a quantitative description of the translocation process.
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Affiliation(s)
- Jalal Sarabadani
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), 19395-5531, Tehran, Iran. Interdisciplinary Centre for Mathematical Modelling, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom. Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom. Department of Applied Physics and QTF Center of Excellence, Aalto University School of Science, PO Box 11000, FI-00076 Aalto, Espoo, Finland
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27
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Pomposo JA, Rubio-Cervilla J, Gonzalez E, Moreno AJ, Arbe A, Colmenero J. Ultrafiltration of single-chain polymer nanoparticles through nanopores and nanoslits. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.06.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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28
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Kumar R, Chaudhuri A, Kapri R. Sequencing of semiflexible polymers of varying bending rigidity using patterned pores. J Chem Phys 2018; 148:164901. [PMID: 29716219 DOI: 10.1063/1.5036529] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the translocation of a semiflexible polymer through extended pores with patterned stickiness, using Langevin dynamics simulations. We find that the consequence of pore patterning on the translocation time dynamics is dramatic and depends strongly on the interplay of polymer stiffness and pore-polymer interactions. For heterogeneous polymers with periodically varying stiffness along their lengths, we find that variation of the block size of the sequences and the orientation results in large variations in the translocation time distributions. We show how this fact may be utilized to develop an effective sequencing strategy. This strategy involving multiple pores with patterned surface energetics can predict heteropolymer sequences having different bending rigidity to a high degree of accuracy.
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Affiliation(s)
- Rajneesh Kumar
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
| | - Abhishek Chaudhuri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
| | - Rajeev Kapri
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, S. A. S. Nagar, Manauli 140306, India
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29
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Katkar HH, Muthukumar M. Role of non-equilibrium conformations on driven polymer translocation. J Chem Phys 2018; 148:024903. [PMID: 29331138 PMCID: PMC5764753 DOI: 10.1063/1.4994204] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 12/28/2017] [Indexed: 11/14/2022] Open
Abstract
One of the major theoretical methods in understanding polymer translocation through a nanopore is the Fokker-Planck formalism based on the assumption of quasi-equilibrium of polymer conformations. The criterion for applicability of the quasi-equilibrium approximation for polymer translocation is that the average translocation time per Kuhn segment, ⟨τ⟩/NK, is longer than the relaxation time τ0 of the polymer. Toward an understanding of conditions that would satisfy this criterion, we have performed coarse-grained three dimensional Langevin dynamics and multi-particle collision dynamics simulations. We have studied the role of initial conformations of a polyelectrolyte chain (which were artificially generated with a flow field) on the kinetics of its translocation across a nanopore under the action of an externally applied transmembrane voltage V (in the absence of the initial flow field). Stretched (out-of-equilibrium) polyelectrolyte chain conformations are deliberately and systematically generated and used as initial conformations in translocation simulations. Independent simulations are performed to study the relaxation behavior of these stretched chains, and a comparison is made between the relaxation time scale and the mean translocation time (⟨τ⟩). For such artificially stretched initial states, ⟨τ⟩/NK < τ0, demonstrating the inapplicability of the quasi-equilibrium approximation. Nevertheless, we observe a scaling of ⟨τ⟩ ∼ 1/V over the entire range of chain stretching studied, in agreement with the predictions of the Fokker-Planck model. On the other hand, for realistic situations where the initial artificially imposed flow field is absent, a comparison of experimental data reported in the literature with the theory of polyelectrolyte dynamics reveals that the Zimm relaxation time (τZimm) is shorter than the mean translocation time for several polymers including single stranded DNA (ssDNA), double stranded DNA (dsDNA), and synthetic polymers. Even when these data are rescaled assuming a constant effective velocity of translocation, it is found that for flexible (ssDNA and synthetic) polymers with NK Kuhn segments, the condition ⟨τ⟩/NK < τZimm is satisfied. We predict that for flexible polymers such as ssDNA, a crossover from quasi-equilibrium to non-equilibrium behavior would occur at NK ∼ O(1000).
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Affiliation(s)
- H H Katkar
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - M Muthukumar
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
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30
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Sarabadani J, Ghosh B, Chaudhury S, Ala-Nissila T. Dynamics of end-pulled polymer translocation through a nanopore. EPL (EUROPHYSICS LETTERS) 2017; 120:38004. [DOI: 10.1209/0295-5075/120/38004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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31
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Sarabadani J, Ikonen T, Mökkönen H, Ala-Nissila T, Carson S, Wanunu M. Driven translocation of a semi-flexible polymer through a nanopore. Sci Rep 2017; 7:7423. [PMID: 28785040 PMCID: PMC5547125 DOI: 10.1038/s41598-017-07227-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 06/26/2017] [Indexed: 01/05/2023] Open
Abstract
We study the driven translocation of a semi-flexible polymer through a nanopore by means of a modified version of the iso-flux tension propagation theory, and extensive molecular dynamics (MD) simulations. We show that in contrast to fully flexible chains, for semi-flexible polymers with a finite persistence length [Formula: see text] the trans side friction must be explicitly taken into account to properly describe the translocation process. In addition, the scaling of the end-to-end distance R N as a function of the chain length N must be known. To this end, we first derive a semi-analytic scaling form for R N, which reproduces the limits of a rod, an ideal chain, and an excluded volume chain in the appropriate limits. We then quantitatively characterize the nature of the trans side friction based on MD simulations. Augmented with these two factors, the theory shows that there are three main regimes for the scaling of the average translocation time τ ∝ N α . In the rod [Formula: see text], Gaussian [Formula: see text] and excluded volume chain [Formula: see text] ≫ 10 6 limits, α = 2, 3/2 and 1 + ν, respectively, where ν is the Flory exponent. Our results are in good agreement with available simulations and experimental data.
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Affiliation(s)
- Jalal Sarabadani
- Department of Applied Physics and COMP Center of Excellence, Aalto University School of Science, P.O. Box 11000, FI-00076, Aalto, Espoo, Finland.
| | - Timo Ikonen
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044, VTT, Finland
| | - Harri Mökkönen
- Department of Applied Physics and COMP Center of Excellence, Aalto University School of Science, P.O. Box 11000, FI-00076, Aalto, Espoo, Finland
| | - Tapio Ala-Nissila
- Department of Applied Physics and COMP Center of Excellence, Aalto University School of Science, P.O. Box 11000, FI-00076, Aalto, Espoo, Finland
- Department of Mathematical Sciences and Department of Physics, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
| | - Spencer Carson
- Department of Physics, Northeastern University, Boston, MA, 02115, United States
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, MA, 02115, United States
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32
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Abstract
We use an accurate coarse-grained model for DNA and stochastic molecular dynamics simulations to study the pore translocation of 10-kbp-long DNA rings that are knotted. By monitoring various topological and physical observables we find that there is not one, as previously assumed, but rather two qualitatively different modes of knot translocation. For both modes the pore obstruction caused by knot passage has a brief duration and typically occurs at a late translocation stage. Both effects are well in agreement with experiments and can be rationalized with a transparent model based on the concurrent tensioning and sliding of the translocating knotted chains. We also observed that the duration of the pore obstruction event is more controlled by the knot translocation velocity than the knot size. These features should advance the interpretation and design of future experiments aimed at probing the spontaneous knotting of biopolymers.
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Affiliation(s)
- Antonio Suma
- Molecular and Statistical Biophysics, International School for Advanced Studies (SISSA), I-34136 Trieste, Italy
| | - Cristian Micheletti
- Molecular and Statistical Biophysics, International School for Advanced Studies (SISSA), I-34136 Trieste, Italy
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33
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Sean D, Slater GW. Highly driven polymer translocation from a cylindrical cavity with a finite length. J Chem Phys 2017; 146:054903. [DOI: 10.1063/1.4975091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- David Sean
- University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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34
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Sakaue T. Dynamics of Polymer Translocation: A Short Review with an Introduction of Weakly-Driven Regime. Polymers (Basel) 2016; 8:E424. [PMID: 30974699 PMCID: PMC6432367 DOI: 10.3390/polym8120424] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/25/2016] [Accepted: 12/01/2016] [Indexed: 12/22/2022] Open
Abstract
As emphasized in a recent review (by V.V. Palyulin, T. Ala-Nissila, R. Metzler), theoretical understanding of the unbiased polymer translocation lags behind that of the (strongly) driven translocation. Here, we suggest the introduction of a weakly-driven regime, as described by the linear response theory to the unbiased regime, which is followed by the strongly-driven regime beyond the onset of nonlinear response. This provides a concise crossover scenario, bridging the unbiased to strongly-driven regimes.
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Affiliation(s)
- Takahiro Sakaue
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Honcho Kawaguchi, Saitama 332-0012, Japan.
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35
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Hsiao PY. Conformation Change, Tension Propagation and Drift-Diffusion Properties of Polyelectrolyte in Nanopore Translocation. Polymers (Basel) 2016; 8:E378. [PMID: 30974654 PMCID: PMC6432159 DOI: 10.3390/polym8100378] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/15/2016] [Accepted: 10/19/2016] [Indexed: 12/17/2022] Open
Abstract
Using Langevin dynamics simulations, conformational, mechanical and dynamical properties of charged polymers threading through a nanopore are investigated. The shape descriptors display different variation behaviors for the cis- and trans-side sub-chains, which reflects a strong cis-trans dynamical asymmetry, especially when the driving field is strong. The calculation of bond stretching shows how the bond tension propagates on the chain backbone, and the chain section straightened by the tension force is determined by the ratio of the direct to the contour distances of the monomer to the pore. With the study of the waiting time function, the threading process is divided into the tension-propagation stage and the tail-retraction stage. At the end, the drift velocity, diffusive property and probability density distribution are explored. Owing to the non-equilibrium nature, translocation is not a simple drift-diffusion process, but exhibits several intermediate behaviors, such as ballistic motion, normal diffusion and super diffusion, before ending with the last, negative-diffusion behavior.
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Affiliation(s)
- Pai-Yi Hsiao
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
- Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
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36
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Vollmer SC, de Haan HW. Translocation is a nonequilibrium process at all stages: Simulating the capture and translocation of a polymer by a nanopore. J Chem Phys 2016; 145:154902. [DOI: 10.1063/1.4964630] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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37
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Mondal D, Muthukumar M. Ratchet rectification effect on the translocation of a flexible polyelectrolyte chain. J Chem Phys 2016; 145:084906. [PMID: 27586945 PMCID: PMC5001978 DOI: 10.1063/1.4961505] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/10/2016] [Indexed: 12/20/2022] Open
Abstract
We report a three dimensional Langevin dynamics simulation of a uniformly charged flexible polyelectrolyte chain, translocating through an asymmetric narrow channel with periodically varying cross sections under the influence of a periodic external electric field. When reflection symmetry of the channel is broken, a rectification effect is observed with a favored direction for the chain translocation. For a given volume of the channel unit and polymer length, the rectification occurs below a threshold frequency of the external periodic driving force. We have also observed that the extent of the rectification varies non-monotonically with increasing molecular weight and the strength of geometric asymmetry of the channel. Observed non-monotonicity of the rectification performance has been interpreted in terms of a competition between two effects arising from the channel asymmetry and change in conformational entropy. An analytical model is presented with predictions consistent with the simulation results.
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Affiliation(s)
- Debasish Mondal
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - M Muthukumar
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
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38
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Sarabadani J, Ikonen T, Ala-Nissila T. Theory of polymer translocation through a flickering nanopore under an alternating driving force. J Chem Phys 2015; 143:074905. [DOI: 10.1063/1.4928743] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Jalal Sarabadani
- Department of Applied Physics and COMP Center of Excellence, Aalto University School of Science, P.O. Box 11000, FI-00076 Aalto, Espoo, Finland
| | - Timo Ikonen
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT, Finland
| | - Tapio Ala-Nissila
- Department of Applied Physics and COMP Center of Excellence, Aalto University School of Science, P.O. Box 11000, FI-00076 Aalto, Espoo, Finland
- Department of Physics, Brown University, P.O. Box 1843, Providence, Rhode Island 02912-1843, USA
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