1
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Agrawal NR, Duan C, Wang R. Nature of Overcharging and Charge Inversion in Electrical Double Layers. J Phys Chem B 2024; 128:303-311. [PMID: 38150660 DOI: 10.1021/acs.jpcb.3c04739] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Understanding overcharging and charge inversion is one of the long-standing challenges in soft matter and biophysics. To study these phenomena, we employ the modified Gaussian renormalized fluctuation theory, which allows for the self-consistent accounting of spatially varying ionic strength as well as the spatial variations in dielectric permittivity and excluded volume effects. The underlying dependence of overcharging on the electrostatic coupling is elucidated by varying the surface charge, counterion valency, and dielectric contrast. Consistent with simulations, three characteristic regimes corresponding to weak, moderate, and strong coupling are identified. Important features like the inversion of zeta potential, crowding, and ionic layering at the surface are successfully captured. For weak coupling, there is no overcharging. In the moderate coupling regime, overcharging increases with the surface charge. Finally, in the strong coupling regime, ionic crowding and saturation in overcharging are observed. Our theory predicts a nonmonotonic dependence of charge inversion on multivalent salt concentration as well as the addition of monovalent salt, in quantitative agreement with experiments.
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Affiliation(s)
- Nikhil R Agrawal
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720-1462, United States
| | - Chao Duan
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720-1462, United States
| | - Rui Wang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720-1462, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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2
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Vahid H, Scacchi A, Sammalkorpi M, Ala-Nissila T. Nonmonotonic electrophoretic mobility of rodlike polyelectrolytes by multivalent coions in added salt. Phys Rev E 2024; 109:014501. [PMID: 38366448 DOI: 10.1103/physreve.109.014501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 11/30/2023] [Indexed: 02/18/2024]
Abstract
It is well established that when multivalent counterions or salts are added to a solution of highly charged polyelectrolytes (PEs), correlation effects can cause charge inversion of the PE, leading to electrophoretic mobility (EM) reversal. In this work, we use coarse-grained molecular-dynamics simulations to unravel the less understood effect of coion valency on EM reversal for rigid DNA-like PEs. We find that EM reversal induced by multivalent counterions is suppressed with increasing coion valency in the salt added and eventually vanishes. Further, we find that EM is enhanced at fixed low salt concentrations for salts with monovalent counterions when multivalent coions with increasing valency are introduced. However, increasing the salt concentration causes a crossover that leads to EM reversal which is enhanced by increasing coion valency at high salt concentration. Remarkably, this multivalent coion-induced EM reversal persists even for low values of PE linear charge densities where multivalent counterions alone cannot induce EM reversal. These results facilitate tuning PE-PE interactions and self-assembly with both coion and counterion valencies.
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Affiliation(s)
- Hossein Vahid
- Department of Applied Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - Alberto Scacchi
- Department of Applied Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, 00076 Aalto, Finland
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
| | - Tapio Ala-Nissila
- Department of Applied Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
- Quantum Technology Finland Center of Excellence, Department of Applied Physics, Aalto University, P.O. Box 11000, 00076 Aalto, Finland
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
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3
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Vahid H, Scacchi A, Sammalkorpi M, Ala-Nissila T. Interactions between Rigid Polyelectrolytes Mediated by Ordering and Orientation of Multivalent Nonspherical Ions in Salt Solutions. PHYSICAL REVIEW LETTERS 2023; 130:158202. [PMID: 37115871 DOI: 10.1103/physrevlett.130.158202] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/23/2022] [Accepted: 03/22/2023] [Indexed: 06/19/2023]
Abstract
Multivalent ions in solutions with polyelectrolytes (PEs) induce electrostatic correlations that can drastically change ion distributions around the PEs and their mutual interactions. Using coarse-grained molecular dynamics simulations, we show how in addition to valency, ion shape and concentration can be harnessed as tools to control rigid like-charged PE-PE interactions. We demonstrate a correlation between the orientational ordering of aspherical ions and how they mediate the effective PE-PE attraction induced by multivalency. The interaction type, strength, and range can thus be externally controlled in ionic solutions. Our results can be used as generic guidelines to tune the self-assembly of like-charged polyelectrolytes by variation of the characteristics of the ions.
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Affiliation(s)
- Hossein Vahid
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Alberto Scacchi
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Tapio Ala-Nissila
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland
- Quantum Technology Finland Center of Excellence, Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland
- Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
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4
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Yang X, Scacchi A, Vahid H, Sammalkorpi M, Ala-Nissila T. Interaction between two polyelectrolytes in monovalent aqueous salt solutions. Phys Chem Chem Phys 2022; 24:21112-21121. [PMID: 36018307 DOI: 10.1039/d2cp02066a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We use the recently developed soft-potential-enhanced Poisson-Boltzmann (SPB) theory to study the interaction between two parallel polyelectrolytes (PEs) in monovalent ionic solutions in the weak-coupling regime. The SPB theory is fitted to ion distributions from coarse-grained molecular dynamics (MD) simulations and benchmarked against all-atom MD modelling for poly(diallyldimethylammonium) (PDADMA). We show that the SPB theory is able to accurately capture the interactions between two PEs at distances beyond the PE radius. For PDADMA positional correlations between the charged groups lead to locally asymmetric PE charge and ion distributions. This gives rise to small deviations from the SPB prediction that appear as short-range oscillations in the potential of mean force. Our results suggest that the SPB theory can be an efficient way to model interactions in chemically specific complex PE systems.
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Affiliation(s)
- Xiang Yang
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland.
| | - Alberto Scacchi
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland. .,Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.,Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Hossein Vahid
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland. .,Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.,Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.,Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.,Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Tapio Ala-Nissila
- Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland. .,QTF Center of Excellence, Department of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland.,Interdisciplinary Center for Mathematical Modelling and Department of Mathematical Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
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5
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Buyukdagli S. Explicit solvent effects on macromolecular interactions from a solvent-augmented contact value theorem. Phys Rev E 2022; 106:014608. [PMID: 35974608 DOI: 10.1103/physreve.106.014608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
The Derjaguin-Landau-Verywey-Overbeek (DLVO) theory has been a remarkably accurate framework for the characterization of macromolecular stability in water solvent. In view of its solvent-implicit nature neglecting the electrostatics of water molecules with non-negligible charge structure and concentration, the precision of the DLVO formalism is somewhat puzzling. In order to shed light on this issue, we derive from our earlier explicit solvent formalism [S. Buyukdagli et al., Phys. Rev. E 87, 063201 (2013)1539-375510.1103/PhysRevE.87.063201] a solvent-augmented contact value theorem and assess the contribution of solvent molecules to the interaction of charged membranes. We find that in the case of hydrophobic membranes with fixed charges embedded in the membrane surface, the nearly exact cancellation of various explicit solvent effects of substantially large magnitude but opposite sign keeps the intermembrane pressure significantly close to the double-layer force of the DLVO theory. Then, in the case of hydrophilic surface charge groups within the aqueous region, due to the spatial separation of the membrane substrate from the location of the fixed charges where the nonlocal dielectric response of the structured solvent is sharply localized, the interfacial field energy and the contact charge densities remain unaffected by the explicit solvent. As a result, the hydration of the lipid head groups suppresses the signature of the solvent molecules from the membrane interaction force.
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Buyukdagli S. Dielectric Manipulation of Polymer Translocation Dynamics in Engineered Membrane Nanopores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:122-131. [PMID: 34958582 DOI: 10.1021/acs.langmuir.1c02174] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The alteration of the dielectric membrane properties by membrane engineering techniques such as carbon nanotube (CNT) coating opens the way to novel molecular transport strategies for biosensing purposes. In this article, we predict a macromolecular transport mechanism enabling the dielectric manipulation of the polymer translocation dynamics in dielectric membrane pores confining mixed electrolytes. In the giant permittivity regime of these engineered membranes governed by attractive polarization forces, multivalent ions adsorbed by the membrane nanopore trigger a monovalent ion separation and set an electroosmotic counterion flow. The drag force exerted by this flow is sufficiently strong to suppress and invert the electrophoretic velocity of anionic polymers and also to generate the mobility of neutral polymers whose speed and direction can be solely adjusted by the charge and concentration of the added multivalent ions. These features identify the dielectrically generated transport mechanism as an efficient means to drive overall neutral or weakly charged analytes that cannot be controlled by an external voltage. We also reveal that, in anionic polymer translocation, multivalent cation addition into the monovalent salt solution amplifies the electric current signal by several factors. The signal amplification is caused by the electrostatic many-body interactions replacing the monovalent polymer counterions by the multivalent cations of higher electric mobility. The strength of this electrokinetic charge discrimination points out the potential of multivalent ions as current amplifiers capable of providing boosted resolution in nanopore-based biosensing techniques.
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7
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Queralt-Martín M, Perini DA, Alcaraz A. Specific adsorption of trivalent cations in biological nanopores determines conductance dynamics and reverses ionic selectivity. Phys Chem Chem Phys 2021; 23:1352-1362. [PMID: 33367433 DOI: 10.1039/d0cp04486e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Adsorption processes are central to ionic transport in industrial and biological membrane systems. Multivalent cations modulate the conductive properties of nanofluidic devices through interactions with charged surfaces that depend principally on the ion charge number. Considering that ion channels are specialized valves that demand a sharp specificity in ion discrimination, we investigate the adsorption dynamics of trace amounts of different salts of trivalent cations in biological nanopores. We consider here OmpF from Escherichia coli, an archetypical protein nanopore, to probe the specificity of biological nanopores to multivalent cations. We systematically compare the effect of three trivalent electrolytes on OmpF current-voltage relationships and characterize the degree of rectification induced by each ion. We also analyze the open channel current noise to determine the existence of equilibrium/non-equilibrium mechanisms of ion adsorption and evaluate the extent of charge inversion through selectivity measurements. We show that the interaction of trivalent electrolytes with biological nanopores occurs via ion-specific adsorption yielding differential modulation of ion conduction and selectivity inversion. We also demonstrate the existence of non-equilibrium fluctuations likely related to ion-dependent trapping-detrapping processes. Our study provides fundamental information relevant to different biological and electrochemical systems where transport phenomena involve ion adsorption in charged surfaces under nanoscale confinement.
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Affiliation(s)
- María Queralt-Martín
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain.
| | - D Aurora Perini
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain.
| | - Antonio Alcaraz
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain.
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8
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Buyukdagli S. Nanofluidic Charge Transport under Strong Electrostatic Coupling Conditions. J Phys Chem B 2020; 124:11299-11309. [PMID: 33231451 DOI: 10.1021/acs.jpcb.0c09638] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The comprehensive depiction of the many-body effects governing nanoconfined electrolytes is an essential step for the conception of nanofluidic devices with optimized performance. By incorporating self-consistently multivalent charges into the Poisson-Boltzmann equation dressed by a background monovalent salt, we investigate the impact of strong-coupling electrostatics on the nanofluidic transport of electrolyte mixtures. We find that the experimentally observed negative streaming currents in anionic nanochannels originate from the collective effect of Cl- attraction by the interfacially adsorbed multivalent cations and the no-slip layer reducing the hydrodynamic contribution of these cations to the net current. The like-charge current condition emerging from this collective mechanism is shown to be the reversal of the average potential within the no-slip zone. Applying the formalism to surface-coated membrane nanoslits located in the giant dielectric permittivity regime, we reveal a new type of streaming current activated by attractive polarization forces. Under the effect of these forces, multivalent ions added to the KCl solution set a charge separation and generate a counterion current between the neutral slit walls where the pure KCl conductivity vanishes. The adjustability of the current characteristics solely via the valency and amount of the added multivalent ions identifies the underlying process as a promising mechanism for nanofluidic ion separation purposes.
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9
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Hsiao PY. Translocation of a Polyelectrolyte through a Nanopore in the Presence of Trivalent Counterions: A Comparison with the Cases in Monovalent and Divalent Salt Solutions. ACS OMEGA 2020; 5:19805-19819. [PMID: 32803076 PMCID: PMC7424739 DOI: 10.1021/acsomega.0c02647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/10/2020] [Indexed: 05/08/2023]
Abstract
A polyelectrolyte threading through a nanopore in a trivalent salt solution is investigated by means of molecular dynamics simulations under a reflective wall boundary. By varying the chain length N and the strength E of the driving electric field applied inside the pore, the translocation time is carefully calculated to get rid of the bouncing effect because of the boundary. The results are analyzed under the scaling form ⟨τ⟩ ∼ N α E -δ and four driving force regimes; namely, the unbiased, the weakly driven, the strongly driven trumpet, and the strongly driven isoflux regime, are distinguished. The exponents are calculated in each regime and compared with the cases in the monovalent and divalent salt solutions. Owing to strong condensation of counter ions, the changes of the exponents in the force regimes are found to be nontrivial. A large increase in translocation time can be, however, achieved as the driving field is weak. The variations of the chain size, the ion condensation, and the effective chain charge show that the process is proceeded in a quasi-equilibrium way in the unbiased regime and deviated to exhibit strong nonequilibrium characteristics as E increases. Several astonishing scaling behaviors of the waiting time function, the translocation velocity, and the diffusion properties are discovered in the study. The results provide deep insights into the phenomena of polyelectrolyte translocation in various salt solutions at different driving forces.
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Affiliation(s)
- Pai-Yi Hsiao
- Department
of Engineering and System Science, National
Tsing Hua University, Hsinchu, Taiwan 30013, R. O. C
- Institute
of Nuclear Engineering and Science, National
Tsing Hua University, Hsinchu, Taiwan 30013, R. O. C
- ,
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10
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Martín-Molina A, Lue L, Quesada-Pérez M, Bohinc K. Interaction between charged lipid vesicles and point- or rod-like trivalent ions. Colloids Surf B Biointerfaces 2019; 178:525-529. [PMID: 31004839 DOI: 10.1016/j.colsurfb.2019.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 01/30/2019] [Accepted: 02/05/2019] [Indexed: 10/27/2022]
Abstract
This work examines the influence of the charge distribution of trivalent cations on their interaction with soft anionic particles, using a combination of experimental measurements and theoretical modelling. In particular, we perform electrophoresis measurements to determine the zeta-potential of anionic liposomes in the presence of spermidine and lanthanum cations. We work in a range of electrolyte concentration where a reversal in the electrophoretic mobility of the liposomes is expected; however, unlike the case of lanthanum cations, spermidine does not induce mobility reversal of liposomes. As a result, the charge distribution within the counterion appears to be a key factor. This conclusion is supported by a theory that accounts for intra-ionic correlations, which has previously been successfully used to describe the colloidal electric double layer. It allows us to model spermidine as rod-like ions and lanthanum cations as point-like ions in order to test the importance of the ionic geometry in the interactions with soft particles such as lipid vesicles.
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Affiliation(s)
- Alberto Martín-Molina
- Departamento de Fisica Aplicada and Instituto Carlos I de Fisica Teorica y Computacional, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - Manuel Quesada-Pérez
- Departamento de Fisica, Escuela Politecnica Superior de Linares, Universidad de Jaen, 23700 Linares, Jaen, Spain
| | - Klemen Bohinc
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena 5, SI-1000 Ljubljana, Slovenia.
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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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12
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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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13
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Kubota T, Lloyd K, Sakashita N, Minato S, Ishida K, Mitsui T. Clog and Release, and Reverse Motions of DNA in a Nanopore. Polymers (Basel) 2019; 11:polym11010084. [PMID: 30960068 PMCID: PMC6401990 DOI: 10.3390/polym11010084] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 12/28/2018] [Accepted: 01/03/2019] [Indexed: 01/29/2023] Open
Abstract
Motions of circular and linear DNA molecules of various lengths near a nanopore of 100 or 200 nm diameter were experimentally observed and investigated by fluorescence microscopy. The movement of DNA molecules through nanopores, known as translocation, is mainly driven by electric fields near and inside the pores. We found significant clogging of nanopores by DNA molecules, particularly by circular DNA and linear T4 DNA (165.65 kbp). Here, the probabilities of DNA clogging events, depending on the DNA length and shape—linear or circular—were determined. Furthermore, two distinct DNA motions were observed: clog and release by linear T4 DNA, and a reverse direction motion at the pore entrance by circular DNA, after which both molecules moved away from the pore. Finite element method-based numerical simulations were performed. The results indicated that DNA molecules with pores 100–200 nm in diameter were strongly influenced by opposing hydrodynamic streaming flow, which was further enhanced by bulky DNA configurations.
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Affiliation(s)
- Tomoya Kubota
- Department of Mathematics and Physics, Aoyama-Gakuin University, Sagamihara Campus L617, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
| | - Kento Lloyd
- Department of Mathematics and Physics, Aoyama-Gakuin University, Sagamihara Campus L617, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
| | - Naoto Sakashita
- Department of Mathematics and Physics, Aoyama-Gakuin University, Sagamihara Campus L617, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
| | - Seiya Minato
- Department of Mathematics and Physics, Aoyama-Gakuin University, Sagamihara Campus L617, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
| | - Kentaro Ishida
- Department of Mathematics and Physics, Aoyama-Gakuin University, Sagamihara Campus L617, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
| | - Toshiyuki Mitsui
- Department of Mathematics and Physics, Aoyama-Gakuin University, Sagamihara Campus L617, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
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14
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Buyukdagli S. Enhanced polymer capture speed and extended translocation time in pressure-solvation traps. Phys Rev E 2018; 97:062406. [PMID: 30011511 DOI: 10.1103/physreve.97.062406] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Indexed: 12/29/2022]
Abstract
The efficiency of nanopore-based biosequencing techniques requires fast anionic polymer capture by like-charged pores followed by a prolonged translocation process. We show that this condition can be achieved by setting a pressure-solvation trap. Polyvalent cation addition to the KCl solution triggers the like-charge polymer-pore attraction. The attraction speeds-up the pressure-driven polymer capture but also traps the molecule at the pore exit, reducing the polymer capture time and extending the polymer escape time by several orders of magnitude. By direct comparison with translocation experiments [D. P. Hoogerheide et al., ACS Nano 8, 7384 (2014)1936-085110.1021/nn5025829], we characterize as well the electrohydrodynamics of polymers transport in pressure-voltage traps. We derive scaling laws that can accurately reproduce the pressure dependence of the experimentally measured polymer translocation velocity and time. We also find that during polymer capture, the electrostatic barrier on the translocating molecule slows down the liquid flow. This prediction identifies the streaming current measurement as a potential way to probe electrostatic polymer-pore interactions.
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Affiliation(s)
- Sahin Buyukdagli
- Department of Physics, Bilkent University, Ankara 06800, Turkey and QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
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15
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Buyukdagli S. Facilitated polymer capture by charge inverted electroosmotic flow in voltage-driven polymer translocation. SOFT MATTER 2018; 14:3541-3549. [PMID: 29682666 DOI: 10.1039/c8sm00620b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The optimal functioning of nanopore-based biosensing tools necessitates rapid polymer capture from the ion reservoir. We identify an ionic correlation-induced transport mechanism that provides this condition without the chemical modification of the polymer or the pore surface. In the typical experimental configuration where a negatively charged silicon-based pore confines a 1 : 1 electrolyte solution, anionic polymer capture is limited by electrostatic polymer-membrane repulsion and the electroosmotic (EO) flow. Added multivalent cations suppress the electrostatic barrier and reverse the pore charge, inverting the direction of the EO flow that drags the polymer to the trans side. This inverted EO flow can be used to speed up polymer capture from the reservoir and to transport weakly or non-uniformly charged polymers that cannot be controlled by electrophoresis.
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Affiliation(s)
- Sahin Buyukdagli
- Department of Physics, Bilkent University, Ankara 06800, Turkey.
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16
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Chou KH, McCallum C, Gillespie D, Pennathur S. An Experimental Approach to Systematically Probe Charge Inversion in Nanofluidic Channels. NANO LETTERS 2018; 18:1191-1195. [PMID: 29266955 DOI: 10.1021/acs.nanolett.7b04736] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Charge inversion of the surfaces of nanofluidic channels occurs in systems with high-surface charge and/or highly charged ions and is of particular interest because of applications in biological and energy conversion systems. However, the details of such charge inversion have not been clearly elucidated. Specifically, although we can experimentally and theoretically show charge inversion, understanding at what conditions charge inversion occurs, as well how much the charge-inverting ions change the surface, are not known. Here, we show a novel experimental approach for uniquely finding both the ζ-potential and adsorption time of charge inverting ions in aqueous nanofluidic systems.
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Affiliation(s)
- Kuang-Hua Chou
- University of California , Santa Barbara, California, 93106, United States
| | | | - Dirk Gillespie
- Rush University Medical Center , Chicago, Illinois, 60612, United States
| | - Sumita Pennathur
- University of California , Santa Barbara, California, 93106, United States
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17
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Buyukdagli S, Ala-Nissila T. Multivalent cation induced attraction of anionic polymers by like-charged pores. J Chem Phys 2017; 147:144901. [DOI: 10.1063/1.4994018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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18
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Buyukdagli S, Ala-Nissila T. Controlling polymer capture and translocation by electrostatic polymer-pore interactions. J Chem Phys 2017; 147:114904. [DOI: 10.1063/1.5004182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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19
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Buyukdagli S. Like-charge attraction and opposite-charge decomplexation between polymers and DNA molecules. Phys Rev E 2017; 95:022502. [PMID: 28297861 DOI: 10.1103/physreve.95.022502] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Indexed: 11/07/2022]
Abstract
We scrutinize the effect of polyvalent ions on polymer-DNA interactions. We extend a recently developed test-charge theory [S. Buyukdagli et al., Phys. Rev. E 94, 042502 (2016)1539-375510.1103/PhysRevE.94.042502] to the case of a stiff polymer interacting with a DNA molecule in an electrolyte mixture. The theory accounts for one-loop level electrostatic correlation effects such as the ionic cloud deformation around the strongly charged DNA molecule as well as image-charge forces induced by the low DNA permittivity. Our model can reproduce and explain various characteristics of the experimental phase diagrams for polymer solutions. First, the addition of polyvalent cations to the electrolyte solution results in the attraction of the negatively charged polymer by the DNA molecule. The glue of the like-charge attraction is the enhanced shielding of the polymer charges by the dense counterion layer at the DNA surface. Second, through the shielding of the DNA-induced electrostatic potential, mono- and polyvalent cations of large concentration both suppress the like-charge attraction. Within the same formalism, we also predict a new opposite-charge repulsion effect between the DNA molecule and a positively charged polymer. In the presence of polyvalent anions such as sulfate or phosphate, their repulsion by the DNA charges leads to the charge screening deficiency of the region around the DNA molecule. This translates into a repulsive force that results in the decomplexation of the polymer from DNA. This opposite-charge repulsion phenomenon can be verified by current experiments and the underlying mechanism can be beneficial to gene therapeutic applications where the control over polymer-DNA interactions is the key factor.
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20
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Buyukdagli S, Blossey R. Beyond Poisson-Boltzmann: fluctuations and fluid structure in a self-consistent theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:343001. [PMID: 27357125 DOI: 10.1088/0953-8984/28/34/343001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Poisson-Boltzmann (PB) theory is the classic approach to soft matter electrostatics and has been applied to numerous physical chemistry and biophysics problems. Its essential limitations are in its neglect of correlation effects and fluid structure. Recently, several theoretical insights have allowed the formulation of approaches that go beyond PB theory in a systematic way. In this topical review, we provide an update on the developments achieved in the self-consistent formulations of correlation-corrected Poisson-Boltzmann theory. We introduce a corresponding system of coupled non-linear equations for both continuum electrostatics with a uniform dielectric constant, and a structured solvent-a dipolar Coulomb fluid-including non-local effects. While the approach is only approximate and also limited to corrections in the so-called weak fluctuation regime, it allows us to include physically relevant effects, as we show for a range of applications of these equations.
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Affiliation(s)
- S Buyukdagli
- Department of Physics, Bilkent University, Ankara 06800, Turkey
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21
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Buyukdagli S, Ala-Nissila T. Electrostatics of polymer translocation events in electrolyte solutions. J Chem Phys 2016; 145:014902. [PMID: 27394120 DOI: 10.1063/1.4954919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We develop an analytical theory that accounts for the image and surface charge interactions between a charged dielectric membrane and a DNA molecule translocating through the membrane. Translocation events through neutral carbon-based membranes are driven by a competition between the repulsive DNA-image-charge interactions and the attractive coupling between the DNA segments on the trans and the cis sides of the membrane. The latter effect is induced by the reduction of the coupling by the dielectric membrane. In strong salt solutions where the repulsive image-charge effects dominate the attractive trans-cis coupling, the DNA molecule encounters a translocation barrier of ≈10 kBT. In dilute electrolytes, the trans-cis coupling takes over image-charge forces and the membrane becomes a metastable attraction point that can trap translocating polymers over long time intervals. This mechanism can be used in translocation experiments in order to control DNA motion by tuning the salt concentration of the solution.
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Affiliation(s)
| | - T 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
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22
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Buyukdagli S, Ala-Nissila T. Electrostatic energy barriers from dielectric membranes upon approach of translocating DNA molecules. J Chem Phys 2016; 144:084902. [PMID: 26931721 DOI: 10.1063/1.4942177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We probe the electrostatic cost associated with the approach phase of DNA translocation events. Within an analytical theory at the Debye-Hückel level, we calculate the electrostatic energy of a rigid DNA molecule interacting with a dielectric membrane. For carbon or silicon based low permittivity neutral membranes, the DNA molecule experiences a repulsive energy barrier between 10 k(B)T and 100 k(B)T. In the case of engineered membranes with high dielectric permittivities, the membrane surface attracts the DNA with an energy of the same magnitude. Both the repulsive and attractive interactions result from image-charge effects and their magnitude survive even for the thinnest graphene-based membranes of size d ≈ 6 Å. For weakly charged membranes, the electrostatic energy is always attractive at large separation distances but switches to repulsive close to the membrane surface. We also characterise the polymer length dependence of the interaction energy. For specific values of the membrane charge density, low permittivity membranes repel short polymers but attract long polymers. Our results can be used to control the strong electrostatic energy of DNA-membrane interactions prior to translocation events by chemical engineering of the relevant system parameters.
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Affiliation(s)
| | - T Ala-Nissila
- Department of Applied Physics and COMP Center of Excellence, Aalto University School of Science, P.O. Box 11000, Espoo, FI-00076 Aalto, Finland
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23
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Ghodrat M, Naji A, Komaie-Moghaddam H, Podgornik R. Ion-mediated interactions between net-neutral slabs: Weak and strong disorder effects. J Chem Phys 2015; 143:234701. [PMID: 26696064 DOI: 10.1063/1.4936940] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We investigate the effective interaction between two randomly charged but otherwise net-neutral, planar dielectric slabs immersed in an asymmetric Coulomb fluid containing a mixture of mobile monovalent and multivalent ions. The presence of charge disorder on the apposed bounding surfaces of the slabs leads to substantial qualitative changes in the way they interact, as compared with the standard picture provided by the van der Waals and image-induced, ion-depletion interactions. While, the latter predict purely attractive interactions between strictly neutral slabs, we show that the combined effects from surface charge disorder, image depletion, Debye (or salt) screening, and also, in particular, their coupling with multivalent ions, give rise to a more diverse behavior for the effective interaction between net-neutral slabs at nano-scale separations. Disorder effects show large variation depending on the properly quantified strength of disorder, leading either to non-monotonic effective interaction with both repulsive and attractive branches when the surface charges are weakly disordered (small disorder variance) or to a dominating attractive interaction that is larger both in its range and magnitude than what is predicted from the van der Waals and image-induced, ion-depletion interactions, when the surfaces are strongly disordered (large disorder variance).
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Affiliation(s)
- Malihe Ghodrat
- School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
| | - Ali Naji
- School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
| | - Haniyeh Komaie-Moghaddam
- School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
| | - Rudolf Podgornik
- Department of Theoretical Physics, J. Stefan Institute, SI-1000 Ljubljana, Slovenia
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Buyukdagli S. Electrostatic interactions in charged nanoslits within an explicit solvent theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:455101. [PMID: 26443128 DOI: 10.1088/0953-8984/27/45/455101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Within a dipolar Poisson-Boltzmann theory including electrostatic correlations, we consider the effect of explicit solvent structure on solvent and ion partition confined to charged nanopores. We develop a relaxation scheme for the solution of this highly non-linear integro-differential equation for the electrostatic potential. The scheme is an extension of the approach previously introduced for simple planes (Buyukdagli and Blossey 2014 J. Chem. Phys. 140 234903) to nanoslit geometry. We show that the reduced dielectric response of solvent molecules at the membrane walls gives rise to an electric field significantly stronger than the field of the classical Poisson-Boltzmann equation. This peculiarity associated with non-local electrostatic interactions results in turn in an interfacial counterion adsorption layer absent in continuum theories. The observation of this enhanced counterion affinity in the very close vicinity of the interface may have important impacts on nanofluidic transport through charged nanopores. Our results indicate the quantitative inaccuracy of solvent implicit nanofiltration theories in predicting the ionic selectivity of membrane nanopores.
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Buyukdagli S, Blossey R, Ala-Nissila T. Ionic current inversion in pressure-driven polymer translocation through nanopores. PHYSICAL REVIEW LETTERS 2015; 114:088303. [PMID: 25768784 DOI: 10.1103/physrevlett.114.088303] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Indexed: 05/24/2023]
Abstract
We predict streaming current inversion with multivalent counterions in hydrodynamically driven polymer translocation events from a correlation-corrected charge transport theory including charge fluctuations around mean-field electrostatics. In the presence of multivalent counterions, electrostatic many-body effects result in the reversal of the DNA charge. The attraction of anions to the charge-inverted DNA molecule reverses the sign of the ionic current through the pore. Our theory allows for a comprehensive understanding of the complex features of the resulting streaming currents. The underlying mechanism is an efficient way to detect DNA charge reversal in pressure-driven translocation experiments with multivalent cations.
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Affiliation(s)
- Sahin Buyukdagli
- Department of Physics, Bilkent University, Ankara 06800, Turkey
- Institut de Recherche Interdisciplinaire USR3078 CNRS and Université Lille I, Parc de la Haute Borne, 52 Avenue de Halley, 59658 Villeneuve d'Ascq, France
| | - Ralf Blossey
- Institut de Recherche Interdisciplinaire USR3078 CNRS and Université Lille I, Parc de la Haute Borne, 52 Avenue de Halley, 59658 Villeneuve d'Ascq, France
| | - T 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, Providence, Box 1843, Rhode Island 02912-1843, USA
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