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Balantič K, Weiss VU, Pittenauer E, Miklavčič D, Kramar P. The role of lipid oxidation on electrical properties of planar lipid bilayers and its importance for understanding electroporation. Bioelectrochemistry 2023; 153:108498. [PMID: 37399652 DOI: 10.1016/j.bioelechem.2023.108498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/05/2023]
Abstract
Electroporation is a useful tool for the manipulation with the cell membrane permeability. Underlying physicochemical processes taking place at the molecular level during electroporation are relatively well studied. However, various processes remain unknown, one of them is lipid oxidation, a chain reaction that causes degradation of lipids, and might explain the long-lasting membrane permeability after the electric field has ceased. The aim of our study was to observe the differences in the electrical properties of planar lipid bilayers, as in vitro cell membrane models, due to lipid oxidation. Phospholipids were chemically oxidized and oxidation products were analysed using mass spectrometry. Electrical properties, resistance R (Ω) and capacitance C (F) were measured using an LCR meter. Using a previously developed measuring device, a linear increasing signal was applied to a stable bilayer in order to measure its breakdown voltage Ubr (V) and lifetime tbr (µs). We observed an increase in conductance and capacitance of the oxidized planar lipid bilayers when compared to their non-oxidized counterparts. With increasing lipid oxidation, the core of the bilayer becomes more polar, and consequently more permeable. Our findings can explain the long-lasting permeability of the cell membrane after electroporation.
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Affiliation(s)
- Katja Balantič
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
| | - Victor U Weiss
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Ernst Pittenauer
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
| | - Peter Kramar
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia.
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2
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Kramar P, Miklavčič D. Effect of the cholesterol on electroporation of planar lipid bilayer. Bioelectrochemistry 2022; 144:108004. [PMID: 34864271 DOI: 10.1016/j.bioelechem.2021.108004] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 11/18/2021] [Accepted: 11/21/2021] [Indexed: 11/21/2022]
Abstract
Electroporation threshold depends on the membrane composition, with cholesterol being one of its key components already studied in the past, but the results were inconclusive. The aim of our study was to determine behaviour of planar lipid bilayers with varying cholesterol concentrations under electric field. This would give us a better insight into cholesterol effect on membrane properties during electroporation process, since cholesterol is one of the major components of biological membranes and plays a crucial role in membrane organisation, dynamics, and function. Planar lipid bilayers were prepared from phosphatidylcholine lipids with 0, 20, 30, 50 and 80 mol% cholesterol. Capacitance was measured using the discharge method. Results show no statistical difference of cBLM between the cholesterol concentrations. Breakdown voltage Ubr of planar lipid bilayers was measured by means of linear rising voltage with seven different slopes. Obtained results were fitted to a strength-duration curve, where parameter Ubrmin represents minimal breakdown voltage, and parameter τRC represents the inclination of the strength-duration curve. Adding cholesterol to planar lipid bilayer gradually increased its Ubrmin until 50 mol% cholesterol concentration. Afterwards at 80 mol% Ubrmin does not further increase, in fact it reduces by 20% of the Ubrmin at 50 mol% cholesterol concentration.
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Affiliation(s)
- Peter Kramar
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia.
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
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3
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Water Pores in Planar Lipid Bilayers at Fast and Slow Rise of Transmembrane Voltage. MEMBRANES 2021; 11:membranes11040263. [PMID: 33916447 PMCID: PMC8067013 DOI: 10.3390/membranes11040263] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 12/12/2022]
Abstract
Basic understanding of the barrier properties of biological membranes can be obtained by studying model systems, such as planar lipid bilayers. Here, we study water pores in planar lipid bilayers in the presence of transmembrane voltage. Planar lipid bilayers were exposed to fast and slow linearly increasing voltage and current signals. We measured the capacitance, breakdown voltage, and rupture time of planar lipid bilayers composed of 1-pamitoyl 2-oleoyl phosphatidylcholine (POPC), 1-pamitoyl 2-oleoyl phosphatidylserine (POPS), and a mixture of both lipids in a 1:1 ratio. Based on the measurements, we evaluated the change in the capacitance of the planar lipid bilayer corresponding to water pores, the radius of water pores at membrane rupture, and the fraction of the area of the planar lipid bilayer occupied by water pores.planar lipid bilayer capacitance, which corresponds to water pores, water pore radius at the membrane rupture, and a fraction of the planar lipid bilayer area occupied by water pores. The estimated pore radii determining the rupture of the planar lipid bilayer upon fast build-up of transmembrane voltage are 0.101 nm, 0.110 nm, and 0.106 nm for membranes composed of POPC, POPS, and POPC:POPS, respectively. The fraction of the surface occupied by water pores at the moment of rupture of the planar lipid bilayer The fraction of an area that is occupied by water pores at the moment of planar lipid bilayer rupture is in the range of 0.1–1.8%.
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4
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Aycock KN, Davalos RV. Irreversible Electroporation: Background, Theory, and Review of Recent Developments in Clinical Oncology. Bioelectricity 2019; 1:214-234. [PMID: 34471825 PMCID: PMC8370296 DOI: 10.1089/bioe.2019.0029] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Irreversible electroporation (IRE) has established a clinical niche as an alternative to thermal ablation for the eradication of unresectable tumors, particularly those near critical vascular structures. IRE has been used in over 50 independent clinical trials and has shown clinical success when used as a standalone treatment and as a single component within combinatorial treatment paradigms. Recently, many studies evaluating IRE in larger patient cohorts and alongside other novel therapies have been reported. Here, we present the basic principles of reversible electroporation and IRE followed by a review of preclinical and clinical data with a focus on tumors in three organ systems in which IRE has shown great promise: the prostate, pancreas, and liver. Finally, we discuss alternative and future developments, which will likely further advance the use of IRE in the clinic.
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Affiliation(s)
- Kenneth N Aycock
- Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University, Blacksburg, Virginia
| | - Rafael V Davalos
- Department of Biomedical Engineering and Mechanics, Virginia Tech-Wake Forest University, Blacksburg, Virginia
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Kotnik T, Rems L, Tarek M, Miklavčič D. Membrane Electroporation and Electropermeabilization: Mechanisms and Models. Annu Rev Biophys 2019; 48:63-91. [PMID: 30786231 DOI: 10.1146/annurev-biophys-052118-115451] [Citation(s) in RCA: 339] [Impact Index Per Article: 67.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exposure of biological cells to high-voltage, short-duration electric pulses causes a transient increase in their plasma membrane permeability, allowing transmembrane transport of otherwise impermeant molecules. In recent years, large steps were made in the understanding of underlying events. Formation of aqueous pores in the lipid bilayer is now a widely recognized mechanism, but evidence is growing that changes to individual membrane lipids and proteins also contribute, substantiating the need for terminological distinction between electroporation and electropermeabilization. We first revisit experimental evidence for electrically induced membrane permeability, its correlation with transmembrane voltage, and continuum models of electropermeabilization that disregard the molecular-level structure and events. We then present insights from molecular-level modeling, particularly atomistic simulations that enhance understanding of pore formation, and evidence of chemical modifications of membrane lipids and functional modulation of membrane proteins affecting membrane permeability. Finally, we discuss the remaining challenges to our full understanding of electroporation and electropermeabilization.
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Affiliation(s)
- Tadej Kotnik
- Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; ,
| | - Lea Rems
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, 17165 Solna, Sweden;
| | - Mounir Tarek
- Université de Lorraine, CNRS, LPCT, F-54000 Nancy, France;
| | - Damijan Miklavčič
- Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; ,
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Vaiwala R, Jadhav S, Thaokar R. Electroporation Using Dissipative Particle Dynamics with a Novel Protocol for Applying Electric Field. J Chem Theory Comput 2019; 15:603-612. [PMID: 30525589 DOI: 10.1021/acs.jctc.8b00911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In molecular dynamics simulations of membrane electroporation, the bilayer is subjected to an electric field E either by direct addition of a force f = qE on the charge-bearing species or by imposing an ion imbalance in the salt solutions on the two sides of the bilayer. The former is believed to mimic electroporation with high fields over nanosecond pulse period, during which the membrane is almost uncharged, especially in the low salt limit. Conversely, the ion imbalance method elucidates a low electric field-induced poration over a longer period of micro- to milliseconds with a fully charged membrane. Both these methods of applying electric field have disadvantages while investigating electroporation using dissipative particle dynamics (DPD) simulations. The method involving direct addition of force fails to address the presence of a nonuniform dielectric background for ions embedded in nonpolarizable DPD water and those found in the core of the bilayer. The ion imbalance method in DPD simulations suffers from its unavoidable use of a wall potential to prevent the movement of ions across the periodic boundaries. To address the above issues, we propose a simple method for imposing a desired transmembrane potential (TMV) by placing oppositely but uniformly charged plates on either side of the bilayer. Our DPD simulations demonstrate that the profiles for bead density, mechanical stress, electrical potential, as well as the transient responses in the dipole moment and species fluxes obtained from the proposed method utilizing charged plates are quite similar to those obtained using the ion imbalance method. The proposed protocol is free from the aforementioned drawbacks of the direct force addition and ion imbalance methods.
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Affiliation(s)
- Rakesh Vaiwala
- Department of Chemical Engineering , Indian Institute of Technology Bombay , Mumbai 400 076 , India
| | - Sameer Jadhav
- Department of Chemical Engineering , Indian Institute of Technology Bombay , Mumbai 400 076 , India
| | - Rochish Thaokar
- Department of Chemical Engineering , Indian Institute of Technology Bombay , Mumbai 400 076 , India
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Marracino P, Bernardi M, Liberti M, Del Signore F, Trapani E, Gárate JA, Burnham CJ, Apollonio F, English NJ. Transprotein-Electropore Characterization: A Molecular Dynamics Investigation on Human AQP4. ACS OMEGA 2018; 3:15361-15369. [PMID: 30556005 PMCID: PMC6288775 DOI: 10.1021/acsomega.8b02230] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/22/2018] [Indexed: 06/09/2023]
Abstract
Electroporation characterization is a topic of intensive interest probed by extensive ongoing research efforts. Usually, these studies are carried out on lipid-bilayer electroporation. Surprisingly, the possibility of water-channel electropore formation across transmembrane proteins themselves, particularly in view of such a promising application, has not yet been elucidated. The present work examines the geometrical and kinetic aspects of electropores and their stability in such a protein milieux (as opposed through the phospholipid membranes) in depth, by means of scrutiny of such a process in human-AQP4 as a well-representative prototype. The residues forming the electropore's walls, organized in loops, reveal the formation mechanism by their dipole alignment and translational response in response to applied axial electric fields in nonequilibrium molecular dynamics simulation. The magnitude of sustaining electric fields (keeping a stable electropore open) were determined. This suggests that transmembrane proteins could play a central role in electroporation applications, e.g., in medicine and biotechnology.
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Affiliation(s)
- Paolo Marracino
- Department
of Information Engineering, Electronics and Telecommunications, La Sapienza University, 00184 Rome, Italy
| | - Mario Bernardi
- Department
of Information Engineering, Electronics and Telecommunications, La Sapienza University, 00184 Rome, Italy
| | - Micaela Liberti
- Department
of Information Engineering, Electronics and Telecommunications, La Sapienza University, 00184 Rome, Italy
| | - Federico Del Signore
- Department
of Information Engineering, Electronics and Telecommunications, La Sapienza University, 00184 Rome, Italy
| | - Erika Trapani
- Department
of Information Engineering, Electronics and Telecommunications, La Sapienza University, 00184 Rome, Italy
| | - José-Antonio Gárate
- Centro
Interdisciplinario de neurociencia de Valparaiso, Universidad de Valparaiso, 05101 Valparaiso, Chile
| | - Christian J. Burnham
- School
of Chemical and Bioprocess Engineering, University College Dublin, Belfield, D4 Dublin, Ireland
| | - Francesca Apollonio
- Department
of Information Engineering, Electronics and Telecommunications, La Sapienza University, 00184 Rome, Italy
| | - Niall J. English
- School
of Chemical and Bioprocess Engineering, University College Dublin, Belfield, D4 Dublin, Ireland
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8
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Atomistic Simulations of Electroporation of Model Cell Membranes. ADVANCES IN ANATOMY EMBRYOLOGY AND CELL BIOLOGY 2018; 227:1-15. [PMID: 28980037 DOI: 10.1007/978-3-319-56895-9_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Electroporation is a phenomenon that modifies the fundamental function of the cell since it perturbs transiently or permanently the integrity of its membrane. Today, this technique is applied in fields ranging from biology and biotechnology to medicine, e.g., for drug and gene delivery into cells, tumor therapy, etc., in which it made it to preclinical and clinical treatments. Experimentally, due to the complexity and heterogeneity of cell membranes, it is difficult to provide a description of the electroporation phenomenon in terms of atomically resolved structural and dynamical processes, a prerequisite to optimize its use. Atomistic modeling in general and molecular dynamics (MD) simulations in particular have proven to be an effective approach for providing such a level of detail. This chapter provides the reader with a comprehensive account of recent advances in using such a technique to complement conventional experimental approaches in characterizing several aspects of cell membranes electroporation.
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Sweeney DC, Douglas TA, Davalos RV. Characterization of Cell Membrane Permeability In Vitro Part II: Computational Model of Electroporation-Mediated Membrane Transport. Technol Cancer Res Treat 2018; 17:1533033818792490. [PMID: 30231776 PMCID: PMC6149036 DOI: 10.1177/1533033818792490] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/18/2018] [Accepted: 07/03/2018] [Indexed: 12/22/2022] Open
Abstract
Electroporation is the process by which applied electric fields generate nanoscale defects in biological membranes to more efficiently deliver drugs and other small molecules into the cells. Due to the complexity of the process, computational models of cellular electroporation are difficult to validate against quantitative molecular uptake data. In part I of this two-part report, we describe a novel method for quantitatively determining cell membrane permeability and molecular membrane transport using fluorescence microscopy. Here, in part II, we use the data from part I to develop a two-stage ordinary differential equation model of cellular electroporation. We fit our model using experimental data from cells immersed in three buffer solutions and exposed to electric field strengths of 170 to 400 kV/m and pulse durations of 1 to 1000 μs. We report that a low-conductivity 4-(2-hydroxyethyl)-1 piperazineethanesulfonic acid buffer enables molecular transport into the cell to increase more rapidly than with phosphate-buffered saline or culture medium-based buffer. For multipulse schemes, our model suggests that the interpulse delay between two opposite polarity electric field pulses does not play an appreciable role in the resultant molecular uptake for delays up to 100 μs. Our model also predicts the per-pulse permeability enhancement decreases as a function of the pulse number. This is the first report of an ordinary differential equation model of electroporation to be validated with quantitative molecular uptake data and consider both membrane permeability and charging.
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Affiliation(s)
- Daniel C. Sweeney
- Department of Biomedical Engineering and Mechanics, Virginia Tech,
Blacksburg, VA, USA
| | - Temple A. Douglas
- Department of Biomedical Engineering and Mechanics, Virginia Tech,
Blacksburg, VA, USA
| | - Rafael V. Davalos
- Department of Biomedical Engineering and Mechanics, Virginia Tech,
Blacksburg, VA, USA
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Rems L, Tarek M, Casciola M, Miklavčič D. Properties of lipid electropores II: Comparison of continuum-level modeling of pore conductance to molecular dynamics simulations. Bioelectrochemistry 2016; 112:112-24. [DOI: 10.1016/j.bioelechem.2016.03.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/24/2016] [Accepted: 03/27/2016] [Indexed: 12/18/2022]
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11
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Casciola M, Tarek M. A molecular insight into the electro-transfer of small molecules through electropores driven by electric fields. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2278-2289. [PMID: 27018309 DOI: 10.1016/j.bbamem.2016.03.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 03/21/2016] [Accepted: 03/21/2016] [Indexed: 11/26/2022]
Abstract
The transport of chemical compounds across the plasma membrane into the cell is relevant for several biological and medical applications. One of the most efficient techniques to enhance this uptake is reversible electroporation. Nevertheless, the detailed molecular mechanism of transport of chemical species (dyes, drugs, genetic materials, …) following the application of electric pulses is not yet fully elucidated. In the past decade, molecular dynamics (MD) simulations have been conducted to model the effect of pulsed electric fields on membranes, describing several aspects of this phenomenon. Here, we first present a comprehensive review of the results obtained so far modeling the electroporation of lipid membranes, then we extend these findings to study the electrotransfer across lipid bilayers subject to microsecond pulsed electric fields of Tat11, a small hydrophilic charged peptide, and of siRNA. We use in particular a MD simulation protocol that allows to characterize the transport of charged species through stable pores. Unexpectedly, our results show that for an electroporated bilayer subject to transmembrane voltages in the order of 500mV, i.e. consistent with experimental conditions, both Tat11 and siRNA can translocate through nanoelectropores within tens of ns. We discuss these results in comparison to experiments in order to rationalize the mechanism of drug uptake by cells. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Maura Casciola
- Université de Lorraine, UMR 7565, F-54506 Vandoeuvre les Nancy, France; Department of Information Engineering, Electronics and Telecommunications (D.I.E.T), Sapienza University of Rome, 00184 Rome, Italy; Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, 00161 Rome, Italy
| | - Mounir Tarek
- Université de Lorraine, UMR 7565, F-54506 Vandoeuvre les Nancy, France; CNRS, UMR 7565, F-54506 Vandoeuvre les Nancy, France.
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12
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Velikonja A, Kramar P, Miklavčič D, Maček Lebar A. Specific electrical capacitance and voltage breakdown as a function of temperature for different planar lipid bilayers. Bioelectrochemistry 2016; 112:132-7. [PMID: 26948707 DOI: 10.1016/j.bioelechem.2016.02.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 02/15/2016] [Accepted: 02/23/2016] [Indexed: 12/16/2022]
Abstract
The breakdown voltage and specific electrical capacitance of planar lipid bilayers formed from lipids isolated from the membrane of archaeon Aeropyrum pernix K1 as a function of temperature were studied and compared with data obtained previously in MD simulation studies. Temperature dependence of breakdown voltage and specific electrical capacitance was measured also for dipalmitoylphosphatidylcholine (DPPC) bilayers and bilayers formed from mixture of diphytanoylphosphocholine (DPhPC) and DPPC in ratio 80:20. The breakdown voltage of archaeal lipids planar lipid bilayers is more or less constant until 50°C, while at higher temperatures a considerable drop is observed, which is in line with the results from MD simulations. The breakdown voltage of DPPC planar lipid bilayer at melting temperature is considerably higher than in the gel phase. Specific electrical capacitance of planar lipid bilayers formed from archaeal lipids is approximately constant for temperatures up to 40°C and then gradually decreases. The difference with MD simulation predictions is discussed. Specific electrical capacitance of DPPC planar lipid bilayers in fluid phase is 1.75 times larger than that of the gel phase and it follows intermediated phases before phase transition. Increase in specific electrical capacitance while approaching melting point of DPPC is visible also for DPhPC:DPPC mixture.
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Affiliation(s)
- Aljaž Velikonja
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
| | - Peter Kramar
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Slovenia
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13
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Sungailaitė S, Ruzgys P, Šatkauskienė I, Čepurnienė K, Šatkauskas S. The dependence of efficiency of transmembrane molecular transfer using electroporation on medium viscosity. J Gene Med 2016; 17:80-6. [PMID: 25761762 DOI: 10.1002/jgm.2825] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 02/27/2015] [Accepted: 03/02/2015] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND In the present study, we aimed to evaluate the efficiency of drug and gene electrotransfer into cells in vitro depending on medium viscosity. METHODS Experiments were performed using Chinese hamster ovary cells. Efficiency of molecular electrotransfer depending of medium viscosity was evaluated using two different electroporation conditions: a high-voltage (HV) pulse and a combination of a high-voltage pulse and a low-voltage pulse (HV + LV). To evaluate the efficiency of molecular electrotransfer, anticancer drug bleomycin and two different plasmids coding for green fluorescent protein and luciferase were used. RESULTS We found that a slight increase in medium viscosity from 1.3-1.4 mPa·s significantly decreased the transfection efficiency, both in terms of transfected cells and total protein production, which was abolished completely with an increase in medium viscosity to 6.1 mPa·s. Notably, at this medium viscosity, electrotransfer of the small anticancer drug was still efficient. Using HV and HV + LV pulse combinations, we showed that a decrease of DNA electrotransfer, especially at lower medium viscosities, can be compensated for by the LV pulse to some extent. On the other hand, the addition of the LV pulse after the HV pulse did not have any positive effect on the efficiency of bleomycin electrotransfer. CONCLUSIONS These findings demonstrate that transfection is very susceptible to medium viscosity and highlights the importance of the electrophoretic component in experiments when a considerable transfection level is needed.
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Affiliation(s)
- Sandra Sungailaitė
- Biophysical Research Group, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania.,Emergency Department, Southampton General Hospital, University Hospital Southampton Foundation Trust (UHS), Southampton, UK
| | - Paulius Ruzgys
- Biophysical Research Group, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania
| | - Ingrida Šatkauskienė
- Biophysical Research Group, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania
| | - Karolina Čepurnienė
- Biophysical Research Group, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania
| | - Saulius Šatkauskas
- Biophysical Research Group, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania
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14
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Casciola M, Kasimova MA, Rems L, Zullino S, Apollonio F, Tarek M. Properties of lipid electropores I: Molecular dynamics simulations of stabilized pores by constant charge imbalance. Bioelectrochemistry 2016; 109:108-16. [PMID: 26883056 DOI: 10.1016/j.bioelechem.2016.01.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/20/2016] [Accepted: 01/26/2016] [Indexed: 11/16/2022]
Abstract
Molecular dynamics (MD) simulations have become a powerful tool to study electroporation (EP) in atomic detail. In the last decade, numerous MD studies have been conducted to model the effect of pulsed electric fields on membranes, providing molecular models of the EP process of lipid bilayers. Here we extend these investigations by modeling for the first time conditions comparable to experiments using long (μs-ms) low intensity (~kV/cm) pulses, by studying the characteristics of pores formed in lipid bilayers maintained at a constant surface tension and subject to constant charge imbalance. This enables the evaluation of structural (size) and electrical (conductance) properties of the pores formed, providing information hardly accessible directly by experiments. Extensive simulations of EP of simple phosphatidylcholine bilayers in 1M NaCl show that hydrophilic pores with stable radii (1-2.5 nm) form under transmembrane voltages between 420 and 630 mV, allowing for ionic conductance in the range of 6.4-29.5 nS. We discuss in particular these findings and characterize both convergence and size effects in the MD simulations. We further extend these studies in a follow-up paper (Rems et al., Bioelectrochemistry, Submitted), by proposing an improved continuum model of pore conductance consistent with the results from the MD simulations.
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Affiliation(s)
- Maura Casciola
- Université de Lorraine, UMR 7565, F-54506 Vandoeuvre les Nancy, France; Department of Information Engineering, Electronics and Telecommunications (D.I.E.T), Sapienza University of Rome, 00184 Rome, Italy; Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, 00161 Rome, Italy
| | - Marina A Kasimova
- Université de Lorraine, UMR 7565, F-54506 Vandoeuvre les Nancy, France
| | - Lea Rems
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Sara Zullino
- Université de Lorraine, UMR 7565, F-54506 Vandoeuvre les Nancy, France; Department of Information Engineering, Electronics and Telecommunications (D.I.E.T), Sapienza University of Rome, 00184 Rome, Italy
| | - Francesca Apollonio
- Department of Information Engineering, Electronics and Telecommunications (D.I.E.T), Sapienza University of Rome, 00184 Rome, Italy
| | - Mounir Tarek
- Université de Lorraine, UMR 7565, F-54506 Vandoeuvre les Nancy, France; CNRS, UMR 7565, F-54506 Vandoeuvre les Nancy, France.
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15
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Polak A, Velikonja A, Kramar P, Tarek M, Miklavčič D. Electroporation threshold of POPC lipid bilayers with incorporated polyoxyethylene glycol (C12E8). J Phys Chem B 2014; 119:192-200. [PMID: 25495217 DOI: 10.1021/jp509789m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Electroporation relates to a phenomenon in which cell membranes are permeabilized after being exposed to high electric fields. On the molecular level, the mechanism is not yet fully elucidated, although a considerable body of experiments and molecular dynamic (MD) simulations were performed on model membranes. Here we present the results of a combined theoretical and experimental investigation of electroporation of palmitoy-oleoyl-phosphatidylcholine (POPC) bilayers with incorporated polyoxyethylene glycol (C12E8) surfactants. The experimental results show a slight increase of the capacitance and a 22% decrease of the voltage breakdown upon addition of C12E8 to pure POPC bilayers. These results were qualitatively confirmed by the MD simulations. They later revealed that the polyoxyethylene glycol molecules play a major role in the formation of hydrophilic pores in the bilayers above the electroporation threshold. The headgroup moieties of the latter are indeed embedded in the interior of the bilayer, which favors formation of water wires that protrude into its hydrophobic core. When the water wires extend across the whole bilayer, they form channels stabilized by the C12E8 head groups. These hydrophilic channels can transport ions across the membrane without the need of major lipid head-group rearrangements.
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Affiliation(s)
- Andraž Polak
- University of Ljubljana , Faculty of Electrical Engineering, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia
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16
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Cadossi R, Ronchetti M, Cadossi M. Locally enhanced chemotherapy by electroporation: clinical experiences and perspective of use of electrochemotherapy. Future Oncol 2014; 10:877-90. [PMID: 24799067 DOI: 10.2217/fon.13.235] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Electroporation is used to enhance drug diffusion and gene delivery into the cytosol. The combination of electroporation and cytotoxic drugs, electrochemotherapy (ECT), is used to treat metastatic tumor nodules located at the skin and subcutaneous tissue. The objective response rate following a single session of treatment exceeds 80%, with minimal toxicity for the patients. The efficacy of ECT in the bone and visceral metastasis is currently investigated, and Phase II studies have been completed. ECT has been used to treat skin primary tumors, except melanoma, and is under investigation for locally advanced pancreatic cancer. Early evidence suggests that treatment of tumor nodules with ECT recruits components of the immune system and eliciting a systemic immune response against cancer is a challenging clinical perspective. Considering the proven safety in several different clinical applications electroporation should be viewed as a clinical platform technology with wide perspectives for use in ECT, gene therapy and DNA vaccination.
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Affiliation(s)
- Ruggero Cadossi
- Clinical Research, IGEA SpA, Via Parmenide 10/A, Carpi, Italy
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17
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Abstract
Electroporation has been used extensively to transfer DNA to bacteria, yeast, and mammalian cells in culture for the past 30 years. Over this time, numerous advances have been made, from using fields to facilitate cell fusion, delivery of chemotherapeutic drugs to cells and tissues, and most importantly, gene and drug delivery in living tissues from rodents to man. Electroporation uses electrical fields to transiently destabilize the membrane allowing the entry of normally impermeable macromolecules into the cytoplasm. Surprisingly, at the appropriate field strengths, the application of these fields to tissues results in little, if any, damage or trauma. Indeed, electroporation has even been used successfully in human trials for gene delivery for the treatment of tumors and for vaccine development. Electroporation can lead to between 100 and 1000-fold increases in gene delivery and expression and can also increase both the distribution of cells taking up and expressing the DNA as well as the absolute amount of gene product per cell (likely due to increased delivery of plasmids into each cell). Effective electroporation depends on electric field parameters, electrode design, the tissues and cells being targeted, and the plasmids that are being transferred themselves. Most importantly, there is no single combination of these variables that leads to greatest efficacy in every situation; optimization is required in every new setting. Electroporation-mediated in vivo gene delivery has proven highly effective in vaccine production, transgene expression, enzyme replacement, and control of a variety of cancers. Almost any tissue can be targeted with electroporation, including muscle, skin, heart, liver, lung, and vasculature. This chapter will provide an overview of the theory of electroporation for the delivery of DNA both in individual cells and in tissues and its application for in vivo gene delivery in a number of animal models.
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Affiliation(s)
- Jennifer L Young
- Department of Pediatrics, University of Rochester, Rochester, NY, USA
| | - David A Dean
- Departments of Pediatrics and Biomedical Engineering, University of Rochester, Rochester, NY, USA
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18
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Casciola M, Bonhenry D, Liberti M, Apollonio F, Tarek M. A molecular dynamic study of cholesterol rich lipid membranes: comparison of electroporation protocols. Bioelectrochemistry 2014; 100:11-7. [DOI: 10.1016/j.bioelechem.2014.03.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 03/20/2014] [Accepted: 03/20/2014] [Indexed: 01/25/2023]
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Polak A, Tarek M, Tomšič M, Valant J, Ulrih NP, Jamnik A, Kramar P, Miklavčič D. Electroporation of archaeal lipid membranes using MD simulations. Bioelectrochemistry 2014; 100:18-26. [DOI: 10.1016/j.bioelechem.2013.12.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/24/2013] [Accepted: 12/31/2013] [Indexed: 12/13/2022]
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20
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Gurtovenko AA, Lyulina AS. Electroporation of Asymmetric Phospholipid Membranes. J Phys Chem B 2014; 118:9909-18. [DOI: 10.1021/jp5028355] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrey A. Gurtovenko
- Institute
of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi
Prospect V.O. 31, St. Petersburg, 199004 Russia
- Faculty
of Physics, St. Petersburg State University, Ulyanovskaya str. 1, Petrodvorets, St. Petersburg, 198504 Russia
| | - Anastasia S. Lyulina
- Institute
of Physics, Nanotechnology and Telecommunications, St. Petersburg State Polytechnical University, Polytechnicheskaya str. 29, St. Petersburg, 195251 Russia
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21
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Abstract
Membrane electropermeabilization is the observation that the permeability of a cell membrane can be transiently increased when a micro-millisecond external electric field pulse is applied on a cell suspension or on a tissue. Applicative aspects for the transfer of foreign molecules (macromolecules) into the cytoplasm are routinely used. But only a limited knowledge about what is really occurring in the cell and its membranes at the molecular levels is available. This chapter is a critical attempt to report the present state of the art and to point out some of the still open problems. The experimental facts associated to membrane electropermeabilization are firstly reported. They are valid on biological and model systems. Secondly, soft matter approaches give access to the bioelectrochemical description of the thermodynamical constraints supporting the destabilization of simplified models of the biological membrane. It is indeed described as a thin dielectric leaflet, where a molecular transport takes place by electrophoresis and then diffusion. This naïve approach is due to the lack of details on the structural aspects affecting the living systems as shown in a third part. Membranes are part of the cell machinery. The critical property of cells as being an open system from the thermodynamical point of view is almost never present. Computer simulations are now contributing to our knowledge on electropermeabilization. The last part of this chapter is a (very) critical report of all the efforts that have been performed. The final conclusion remains that we still do not know all the details on the reversible structural and dynamical alterations of the cell membrane (and cytoplasm) supporting its electropermeabilization. We have a long way in basic and translational researches to reach a pertinent description.
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Affiliation(s)
- Justin Teissie
- Centre National de la Recherche Scientifique, Institut de Pharmacologie et de Biologie Structurale, Toulouse, France
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22
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Polak A, Bonhenry D, Dehez F, Kramar P, Miklavčič D, Tarek M. On the electroporation thresholds of lipid bilayers: molecular dynamics simulation investigations. J Membr Biol 2013; 246:843-50. [PMID: 23780415 DOI: 10.1007/s00232-013-9570-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 05/31/2013] [Indexed: 10/26/2022]
Abstract
Electroporation relates to the cascade of events that follows the application of high electric fields and that leads to cell membrane permeabilization. Despite a wide range of applications, little is known about the electroporation threshold, which varies with membrane lipid composition. Here, using molecular dynamics simulations, we studied the response of dipalmitoyl-phosphatidylcholine, diphytanoyl-phosphocholine-ester and diphytanoyl-phosphocholine-ether lipid bilayers to an applied electric field. Comparing between lipids with acyl chains and methyl branched chains and between lipids with ether and ester linkages, which change drastically the membrane dipole potential, we found that in both cases the electroporation threshold differed substantially. We show, for the first time, that the electroporation threshold of a lipid bilayer depends not only on the "electrical" properties of the membrane, i.e., its dipole potential, but also on the properties of its component hydrophobic tails.
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Affiliation(s)
- Andraž Polak
- Faculty of Electrical Engineering, University of Ljubljana, Tržaška cesta 25, 1000, Ljubljana, Slovenia,
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23
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Deminsky M, Eletskii A, Kniznik A, Odinokov A, Pentkovskii V, Potapkin B. Molecular dynamic simulation of transmembrane pore growth. J Membr Biol 2013; 246:821-31. [PMID: 23660813 DOI: 10.1007/s00232-013-9552-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 04/19/2013] [Indexed: 01/19/2023]
Abstract
A molecular dynamic approach was applied for simulation of dynamics of pore formation and growth in a phospholipid bilayer in the presence of an external electric field. Processing the simulation results permitted recovery of the kinetic coefficients used in the Einstein-Smoluchowski equation describing the dynamics of pore evolution. Two different models of the bilayer membrane were considered: membrane consisting of POPC and POPE lipids. The simulations permitted us to find nonempirical values of the pore energy parameters, which are compared with empirical values. It was found that the parameters are sensitive to membrane type.
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Affiliation(s)
- M Deminsky
- Kintech Laboratory, Kurchatov Square 1, 123182, Moscow, Russia,
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Yi J, Barrow AJ, Yu N, O'Neill BE. Efficient electroporation of liposomes doped with pore stabilizing nisin. J Liposome Res 2013; 23:197-202. [PMID: 23594238 DOI: 10.3109/08982104.2013.788024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
CONTEXT Liposomes have a long history as passive and active drug carriers. Recently, a few methods have been realized to control the release from liposomes, including heating, ultrasound and laser. OBJECTIVE We report on a new approach to drive release from liposomes using electric fields. MATERIALS AND METHODS Liposomes were manufactured containing a high concentration of (quenched) 5-6 carboxyfluorescein dye. Nisin, a well-known amphiphilic peptide lantibiotic that works by stabilizing pores formed in cell membranes, was mixed in solution inside or outside the liposomes. The liposomes were then electroporated using a range of voltages, and assayed for increases in fluorescence due to release of dye. Release was measured against positive and negative controls, with positive control release driven by a strong detergent. RESULTS Our results demonstrate that the addition of nisin significantly reduces the electric field required to release the contents of liposomes, from 2000 V/m to approximately 200 V/m. This result proves that, in principle, electroporation (EP) of liposomes doped with small amounts of amphiphilic pore stabilizing peptides may be a practical means to drive release of liposomal contents in vivo. CONCLUSION Drug delivery from liposomes doped with amphiphilic peptides using EP is feasible. This technique could be developed into a potent adjuvant to tumor ablation using irreversible EP.
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Affiliation(s)
- Jiang Yi
- Department of Translational Imaging, The Methodist Hospital Research Institute, Houston, TX 77030, USA
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25
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Monovalent ions and water dipoles in contact with dipolar zwitterionic lipid headgroups-theory and MD simulations. Int J Mol Sci 2013; 14:2846-61. [PMID: 23434651 PMCID: PMC3588018 DOI: 10.3390/ijms14022846] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 01/20/2013] [Accepted: 01/21/2013] [Indexed: 01/14/2023] Open
Abstract
The lipid bilayer is a basic building block of biological membranes and can be pictured as a barrier separating two compartments filled with electrolyte solution. Artificial planar lipid bilayers are therefore commonly used as model systems to study the physical and electrical properties of the cell membranes in contact with electrolyte solution. Among them the glycerol-based polar phospholipids which have dipolar, but electrically neutral head groups, are most frequently used in formation of artificial lipid bilayers. In this work the electrical properties of the lipid layer composed of zwitterionic lipids with non-zero dipole moments are studied theoretically. In the model, the zwitterionic lipid bilayer is assumed to be in contact with aqueous solution of monovalent salt ions. The orientational ordering of water, resulting in spatial variation of permittivity, is explicitly taken into account. It is shown that due to saturation effect in orientational ordering of water dipoles the relative permittivity in the zwitterionic headgroup region is decreased, while the corresponding electric potential becomes strongly negative. Some of the predictions of the presented mean-field theoretical consideration are critically evaluated using the results of molecular dynamics (MD) simulation.
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