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Boyd MA, Kamat NP. Visualizing Tension and Growth in Model Membranes Using Optical Dyes. Biophys J 2018; 115:1307-1315. [PMID: 30219285 DOI: 10.1016/j.bpj.2018.08.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 11/16/2022] Open
Abstract
Cells dynamically regulate their membrane surface area during a variety of processes critical to their survival. Recent studies with model membranes have pointed to a general mechanism for surface area regulation under tension in which cell membranes unfold or take up lipid to accommodate membrane strain. Yet we lack robust methods to simultaneously measure membrane tension and surface area changes in real time. Using lipid vesicles that contain two dyes isolated to spatially distinct parts of the membrane, we introduce, to our knowledge, a new method to monitor the processes of membrane stretching and lipid uptake in model membranes. Laurdan, located within the bilayer membrane, and Förster resonance energy transfer dyes, localized to the membrane exterior, act in concert to report changes in membrane tension and lipid uptake during osmotic stress. We use these dyes to show that membranes under tension take up lipid more quickly and in greater amounts compared to their nontensed counterparts. Finally, we show that this technique is compatible with microscopy, enabling real-time analysis of membrane dynamics on a single vesicle level. Ultimately, the combinatorial use of these probes offers a more complete picture of changing membrane morphology. Our optical method allows us to remotely track changes in membrane tension and surface area with model membranes, offering new opportunities to track morphological changes in artificial and biological membranes and providing new opportunities in fields ranging from mechanobiology to drug delivery.
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Affiliation(s)
- Margrethe A Boyd
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois
| | - Neha P Kamat
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois; Center for Synthetic Biology, Northwestern University, Evanston, Illinois; Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois.
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2
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Kundu N, Banerjee P, Dutta R, Kundu S, Saini RK, Halder M, Sarkar N. Proton Transfer Pathways of 2,2'-Bipyridine-3,3'-diol in pH Responsive Fatty Acid Self-Assemblies: Multiwavelength Fluorescence Lifetime Imaging in a Single Vesicle. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:13284-13295. [PMID: 27951700 DOI: 10.1021/acs.langmuir.6b03404] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Fatty acids are known to form different supramolecular aggregates in aqueous solutions depending on the pH of the medium. The dynamics of the transformation of oleate micelles into oleic acid/oleate vesicles has been investigated using a pH-sensitive intramolecular proton transfer fluorophore, 2,2'-bipyridine-3,3'-diol [BP(OH)2]. Different prototropic forms of BP(OH)2 exist in different pH values of the system, and thus, the ground state and the excited state dynamics of BP(OH)2 have been modulated in these confined media. The formation of different tautomeric forms of BP(OH)2 in oleate micelles (at basic pH) is confirmed using time-resolved emission spectra and fluorescence anisotropy measurements. The hydrophobic environment provided by these assemblies reduces the water-assisted nonradiative decay channels and lengthens the fluorescence lifetime of BP(OH)2. The rotational relaxation time in the micellar assembly is higher than that in the vesicle, which may be due to the higher microviscosity sensed by the fluorophore in the micelle. Besides, we have shown for the first time that BP(OH)2 can be used as a membrane-bound fluorophore, using fluorescence lifetime imaging microscopy (FLIM). A broad distribution in the size of the vesicle is observed from the FLIM image. Further, we have used multiwavelength FLIM to collect the FLIM images of a single vesicle at different emission wavelengths, and the lifetime distribution obtained from the FLIM images at different emission wavelengths in a single vesicle correlates well with the lifetime values obtained from the ensemble average measurements in the bulk solution.
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Affiliation(s)
- Niloy Kundu
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
| | - Pavel Banerjee
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
| | - Rupam Dutta
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
| | - Sangita Kundu
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
| | - Rajesh Kumar Saini
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
| | - Mintu Halder
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
| | - Nilmoni Sarkar
- Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, West Bengal, India
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3
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Guchhait B, Biswas R, Ghorai PK. Solute and Solvent Dynamics in Confined Equal-Sized Aqueous Environments of Charged and Neutral Reverse Micelles: A Combined Dynamic Fluorescence and All-Atom Molecular Dynamics Simulation Study. J Phys Chem B 2013; 117:3345-61. [DOI: 10.1021/jp310285k] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Biswajit Guchhait
- Department
of Chemical, Biological and
Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt
Lake, Kolkata 700098, India
| | - Ranjit Biswas
- Department
of Chemical, Biological and
Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt
Lake, Kolkata 700098, India
| | - Pradip K. Ghorai
- Indian Institute of Science Education and Research, Kolkata, Mohanpur Campus, Nadia 741252,
India
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4
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Chiantia S, Klymchenko AS, London E. A novel leaflet-selective fluorescence labeling technique reveals differences between inner and outer leaflets at high bilayer curvature. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:1284-90. [DOI: 10.1016/j.bbamem.2012.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 02/03/2012] [Accepted: 02/06/2012] [Indexed: 11/29/2022]
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5
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Ghatak C, Rao VG, Pramanik R, Sarkar S, Sarkar N. The effect of membrane fluidity on FRET parameters: an energy transfer study inside small unilamellar vesicle. Phys Chem Chem Phys 2010; 13:3711-20. [PMID: 21170434 DOI: 10.1039/c0cp01925a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fluorescence resonance energy transfer (FRET) in a lipid bilayer system containing two different donors and one common acceptor at below and above transition temperature has been studied and all the FRET parameters are analyzed using steady state and time-resolved fluorescence spectroscopy. Using dynamic light scattering measurement, we have followed the process of preparation of small unilamellar vesicles, and by following the FRET parameters of C-153-Rh6G and C-151-Rh6G pairs inside SUVs at 16 °C and 33 °C (T(m) = 23.9 °C) we have noticed that there is greater effect of temperature on the FRET parameters in case of the C-153-Rh6G pair than that of the C-151-Rh6G pair. Finally we have concluded that this difference is due to their different location inside the lipid bilayer in which fluidity of the long alkyl chain markedly affects the FRET parameters for C-153-Rh6G pair embedded inside a small unilamellar vesicle of size 20-50 nm.
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Affiliation(s)
- Chiranjib Ghatak
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, WB, India
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6
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Stevenson SA, Blanchard GJ. Investigating internal structural differences between micelles and unilamellar vesicles of decanoic acid/sodium decanoate. J Phys Chem B 2007; 110:13005-10. [PMID: 16805607 DOI: 10.1021/jp062129m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on the dynamics of a chromophore sequestered within the nonpolar regions of micelles and unilamellar vesicles comprised of decanoic acid/sodium decanoate. We find that there is a measurable difference in the motional dynamics of the chromophore perylene in these two nonpolar media, with the vesicle structure forming a somewhat less viscous environment than the micelle. In all cases, the chromophore reorients as a prolate rotor, implying a local environment with a nominally similar shape for both micelle and vesicle structures. These findings demonstrate that the organization of micelles is measurably different than that of bilayers.
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Affiliation(s)
- Sarah A Stevenson
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322, USA
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Zhang YL, Frangos JA, Chachisvilis M. Laurdan fluorescence senses mechanical strain in the lipid bilayer membrane. Biochem Biophys Res Commun 2006; 347:838-41. [PMID: 16857174 DOI: 10.1016/j.bbrc.2006.06.152] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 06/27/2006] [Indexed: 11/20/2022]
Abstract
The precise molecular mechanisms by which cells transduce a mechanical stimulus into an intracellular biochemical response have not yet been established. Here, we show for the first time that the fluorescence emission of an environment-sensitive membrane probe Laurdan is modulated by mechanical strain of the lipid bilayer membrane. We have measured fluorescence emission of Laurdan in phospholipid vesicles of 30, 50, and 100 nm diameter to show that osmotically induced membrane tension leads to an increase in polarity (hydration depth) of the phospholipid bilayer interior. Our data indicate that the general polarization of Laurdan emission is linearly dependent on membrane tension. We also show that higher membrane curvature leads to higher hydration levels. We anticipate that the proposed method will facilitate future studies of mechanically induced changes in physical properties of lipid bilayer environment both in vitro and in vivo.
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Jurkiewicz P, Sýkora J, Olzyńska A, Humpolícková J, Hof M. Solvent relaxation in phospholipid bilayers: principles and recent applications. J Fluoresc 2006; 15:883-94. [PMID: 16328702 DOI: 10.1007/s10895-005-0013-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Although there exist a number of methods, such as NMR, X-ray, e.g., which explore the hydration of phospholipid bilayers, the solvent relaxation (SR) method has the advantage of simple instrumentation, easy data treatment and possibility of measuring fully hydrated samples. The main information gained from SR by the analysis of recorded "time-resolved emission spectra" (TRES) is micro-viscosity and micro-polarity of the dye microenvironment. Based on these parameters, one can draw conclusions about water structure in the bilayer. In this review, we focus on physical background of this method, on all the procedures that are needed in order to obtain relevant parameters, and on the requirements on the fluorescence dyes. Furthermore, a few recent applications (the effect of curvature, binding of antibacterial peptides and phase transition) illustrating the versatility of this method are mentioned. Moreover, limitations and potential problems are discussed.
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Affiliation(s)
- Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223, Prague 8, Czech Republic
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Sýkora J, Jurkiewicz P, Epand RM, Kraayenhof R, Langner M, Hof M. Influence of the curvature on the water structure in the headgroup region of phospholipid bilayer studied by the solvent relaxation technique. Chem Phys Lipids 2005; 135:213-21. [PMID: 15921979 DOI: 10.1016/j.chemphyslip.2005.03.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Revised: 03/03/2005] [Accepted: 03/07/2005] [Indexed: 11/26/2022]
Abstract
Solvent relaxation (SR) in 1,2-dioleoyl-palmitoyl-sn-glycero-3-phosphocholine (DOPC) unilamellar vesicles of different size was probed by 6-hexadecanoyl-2-(((2-(trimethylammonium)ethyl)methyl)amino)naphthalene chloride (Patman), 6-propionyl-2-dimethylaminonaphthalene (Prodan) and 4-[(n-dodecylthio)methyl]-7-(N,N-dimethylamino)-coumarin (DTMAC). Patman probes the amount and mobility of the bound water molecules located at the carbonyl region of the bilayer. Membrane curvature significantly accelerates the solvent relaxation process, but does not influence the total Stokes shift, showing that membrane curvature increases the mobility, without affecting the amount of water molecules present in the headgroup region. This pattern was also verified for other phosphatidylcholines. Prodan is located in the phosphate region of the bilayer and probes a more polar, mobile and heterogeneous environment than Patman. The influence of membrane curvature on SR probed by Prodan is similar, however, less pronounced compared to Patman. DTMAC (first time used in SR) shows a broad distribution of locations along the z-axis. A substantial amount of the coumarin chromophores face bulk water. No effect of curvature on SR probed by DTMAC is detectable.
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Affiliation(s)
- Jan Sýkora
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223 Prague 8, Czech Republic
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10
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Klymchenko AS, Mély Y, Demchenko AP, Duportail G. Simultaneous probing of hydration and polarity of lipid bilayers with 3-hydroxyflavone fluorescent dyes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1665:6-19. [PMID: 15471566 DOI: 10.1016/j.bbamem.2004.06.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2004] [Revised: 06/15/2004] [Accepted: 06/15/2004] [Indexed: 11/24/2022]
Abstract
The penetration of water into the hydrophobic interior leads to polarity and hydration profiles across lipid membranes which are fundamental in the maintenance of membrane architecture as well as in transport and insertion processes into the membrane. The present paper is an original attempt to evaluate simultaneously polarity and hydration properties of lipid bilayers by a fluorescence approach. We applied two 3-hydroxyflavone probes anchored in lipid bilayers at a relatively precise depth through their attached ammonium groups. They are present in two forms: either in H-bond-free form displaying a two-band emission due to an excited state intramolecular proton transfer reaction (ESIPT), or in H-bonded form displaying a single-band emission with no ESIPT. The individual emission profiles of these forms were obtained by deconvolution of the probes' fluorescence spectra. The polarity of the probe surrounding the bilayer was estimated from the two-band spectra of the H-bond-free form, while the local hydration was estimated from the relative contribution of the two forms. Our results confirm that by increasing the lipid order (phase transition from fluid to gel phase, addition of cholesterol or decrease in the lipid unsaturation), the polarity and to a lesser extent, the hydration of the bilayers decrease simultaneously. In contrast, when fluidity (i.e. lipid order) is kept invariant, increase of temperature and of bilayer curvature leads to a higher bilayer hydration with no effect on the polarity. Furthermore, no correlation was found between dipole potential and the hydration of the bilayers.
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Affiliation(s)
- Andrey S Klymchenko
- Laboratoire de Pharmacologie et Physicochimie, UMR 7034 du CNRS, Faculté de Pharmacie, Université Louis Pasteur, BP 60024, 67401 Illkirch, France.
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11
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Carrozzino JM, Fuguet E, Helburn R, Khaledi MG. Characterization of small unilamellar vesicles using solvatochromic π* indicators and particle sizing. ACTA ACUST UNITED AC 2004; 60:97-115. [PMID: 15262446 DOI: 10.1016/j.jbbm.2004.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2004] [Revised: 04/21/2004] [Accepted: 04/25/2004] [Indexed: 11/29/2022]
Abstract
A suite of small unilamellar vesicles (SUVs) composed of mixtures of phospholipids and cholesterol (CH) or the synthetic surfactant dihexadecyl phosphate (DHP) and cholesterol was investigated using a homologous series of solvatochromic pi* indicators coupled with size exclusion methods and photon correlation spectroscopy (PCS). The solvatochromic method, which is based on the measurement of solvent-dependent shifts in lambda(max) from UV-Vis spectra of solubilized indicators, was used to quantify the dipolarity and polarizability (pi*) of probe solvation environments. The partitioning of the series of individual di-n-alkyl-p-nitroaniline (DNAP) pi* indicators in PG(24)PC(46)Chol(30) and DHP(70)Chol(30) SUVs was examined as a function of the head group structure as well as the method of dye-vesicle preparation. Solubilization of the larger more hydrophobic probes in the bilayer portion of PG(24)PC(46)Chol(30) SUVs was aided through physical entrapment. Such physical methods were not needed for the smaller indicators or for the range of indicators in the DHP(70)Chol(30) dispersions. Extrusion and size-exclusion chromatographic methodologies for the preparation of physically entrapped dopants in SUVs of fixed size range demonstrated that the larger (longer alkyl chain) dopants in the series resided in PG(24)PC(46)Chol(30) liposomes with a wider range of sizes, while the smaller more polar solutes tended to be entrapped in smaller vesicles with a narrower size range.
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Affiliation(s)
- Jennifer M Carrozzino
- Department of Chemistry, North Carolina State University, Box 8204, Raleigh, NC 27695-8204, USA
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12
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Hutterer R, Schneider FW, Sprinz H, Hof M. Binding and relaxation behaviour of prodan and patman in phospholipid vesicles: a fluorescence and 1H NMR study. Biophys Chem 1996; 61:151-60. [PMID: 8956486 DOI: 10.1016/s0301-4622(96)02185-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The relative location, binding behaviour and the solvent relaxation behaviour of the polarity sensitive membrane probes 6-propionyl-2-(dimethylamino)naphthalene and 6-palmitoyl-2-[[trimethylammoniumethyl]methylamino]naphthalene chloride in vesicles composed of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine or egg yolk lecithin have been compared using steady-state and time-resolved fluorescence as well as high resolution NMR measurements. The reconstructed time-resolved emission spectra show unambiguously that the observed spectral shifts in vesicle systems have to be assigned to time-dependent solvent relaxation processes rather than to a probe relocation mechanism. All fluorescence as well as the NMR relaxation data suggest a deeper localization of Patman in the membrane, sensing a less polar and/or more restricted probe environment.
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Affiliation(s)
- R Hutterer
- Institute for Physical Chemistry, University of Wuerzburg, Germany
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Kraayenhof R, Sterk GJ, Wong Fong Sang HW, Krab K, Epand RM. Monovalent cations differentially affect membrane surface properties and membrane curvature, as revealed by fluorescent probes and dynamic light scattering. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1282:293-302. [PMID: 8703985 DOI: 10.1016/0005-2736(96)00069-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The effects of monovalent cations on the interfacial electrostatic potential (psi d), hydrodynamic shear boundary distance (ds), and membrane curvature were studied in large unilamellar phospholipid and galacto/sulfolipid liposomes containing different fractions of negatively charged lipids. The differential effects of alkali metal ions on psi d could be accurately determined at physiological surface charge densities with a surface-anchored fluorescent probe. Li+ and Na+ more effectively decrease psi d and exhibit higher association constants (Kas) than K+ and Cs+. These two groups of cations display qualitatively different perturbations of the interfacial structure. Combining Kas values with the electrokinetic (zeta) potentials yielded the respective ds values. At low ionic strength ds more substantially increases with Li+ or Na+ than with K+ or Cs+. Increasing surface charge density causes increased membrane curvature in the presence of K+ or Cs+, but this is largely prevented by Li+ or Na+. Membrane binding of the amphiphilic cation acridine orange decreases surface charge and membrane curvature more extensively than H3O+, Li+, and Na+. The differential interface-perturbing behavior of monovalent cations is discussed with regard to their different hydration tendencies that will modulate the extent and stability of the hydrogen-bond network along the charged membrane surface.
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Affiliation(s)
- R Kraayenhof
- Institute of Molecular Biological Sciences, BioCentrum Amsterdam, Vrije Universiteit, The Netherlands.
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