1
|
Pašalić L, Pem B, Bakarić D. Lamellarity-Driven Differences in Surface Structural Features of DPPS Lipids: Spectroscopic, Calorimetric and Computational Study. MEMBRANES 2023; 13:83. [PMID: 36676890 PMCID: PMC9865892 DOI: 10.3390/membranes13010083] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/27/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Although single-lipid bilayers are usually considered models of eukaryotic plasma membranes, their research drops drastically when it comes to exclusively anionic lipid membranes. Being a major anionic phospholipid in the inner leaflet of eukaryote membranes, phosphatidylserine-constituted lipid membranes were occasionally explored in the form of multilamellar liposomes (MLV), but their inherent instability caused a serious lack of efforts undertaken on large unilamellar liposomes (LUVs) as more realistic model membrane systems. In order to compensate the existing shortcomings, we performed a comprehensive calorimetric, spectroscopic and MD simulation study of time-varying structural features of LUV made from 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS), whereas the corresponding MLV were examined as a reference. A substantial uncertainty of UV/Vis data of LUV from which only Tm was unambiguously determined (53.9 ± 0.8 °C), along with rather high uncertainty on the high-temperature range of DPPS melting profile obtained from DSC (≈50-59 °C), presumably reflect distinguished surface structural features in LUV. The FTIR signatures of glycerol moiety and those originated from carboxyl group serve as a strong support that in LUV, unlike in MLV, highly curved surfaces occur continuously, whereas the details on the attenuation of surface features in MLV were unraveled by molecular dynamics.
Collapse
|
2
|
Sadžak A, Mravljak J, Maltar-Strmečki N, Arsov Z, Baranović G, Erceg I, Kriechbaum M, Strasser V, Přibyl J, Šegota S. The Structural Integrity of the Model Lipid Membrane during Induced Lipid Peroxidation: The Role of Flavonols in the Inhibition of Lipid Peroxidation. Antioxidants (Basel) 2020; 9:E430. [PMID: 32429305 PMCID: PMC7278707 DOI: 10.3390/antiox9050430] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/29/2020] [Accepted: 05/13/2020] [Indexed: 01/06/2023] Open
Abstract
The structural integrity, elasticity, and fluidity of lipid membranes are critical for cellular activities such as communication between cells, exocytosis, and endocytosis. Unsaturated lipids, the main components of biological membranes, are particularly susceptible to the oxidative attack of reactive oxygen species. The peroxidation of unsaturated lipids, in our case 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), induces the structural reorganization of the membrane. We have employed a multi-technique approach to analyze typical properties of lipid bilayers, i.e., roughness, thickness, elasticity, and fluidity. We compared the alteration of the membrane properties upon initiated lipid peroxidation and examined the ability of flavonols, namely quercetin (QUE), myricetin (MCE), and myricitrin (MCI) at different molar fractions, to inhibit this change. Using Mass Spectrometry (MS) and Fourier Transform Infrared Spectroscopy (FTIR), we identified various carbonyl products and examined the extent of the reaction. From Atomic Force Microscopy (AFM), Force Spectroscopy (FS), Small Angle X-Ray Scattering (SAXS), and Electron Paramagnetic Resonance (EPR) experiments, we concluded that the membranes with inserted flavonols exhibit resistance against the structural changes induced by the oxidative attack, which is a finding with multiple biological implications. Our approach reveals the interplay between the flavonol molecular structure and the crucial membrane properties under oxidative attack and provides insight into the pathophysiology of cellular oxidative injury.
Collapse
Affiliation(s)
- Anja Sadžak
- Ruđer Bošković Institute, 10000 Zagreb, Croatia; (A.S.); (N.M.-S.); (G.B.); (I.E.); (V.S.)
| | - Janez Mravljak
- Faculty of Pharmacy, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Nadica Maltar-Strmečki
- Ruđer Bošković Institute, 10000 Zagreb, Croatia; (A.S.); (N.M.-S.); (G.B.); (I.E.); (V.S.)
| | - Zoran Arsov
- Jožef Stefan Institute, 1000 Ljubljana, Slovenia;
| | - Goran Baranović
- Ruđer Bošković Institute, 10000 Zagreb, Croatia; (A.S.); (N.M.-S.); (G.B.); (I.E.); (V.S.)
| | - Ina Erceg
- Ruđer Bošković Institute, 10000 Zagreb, Croatia; (A.S.); (N.M.-S.); (G.B.); (I.E.); (V.S.)
| | - Manfred Kriechbaum
- Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria;
| | - Vida Strasser
- Ruđer Bošković Institute, 10000 Zagreb, Croatia; (A.S.); (N.M.-S.); (G.B.); (I.E.); (V.S.)
| | - Jan Přibyl
- CEITEC, Masaryk University, 62500 Brno, Czech Republic;
| | - Suzana Šegota
- Ruđer Bošković Institute, 10000 Zagreb, Croatia; (A.S.); (N.M.-S.); (G.B.); (I.E.); (V.S.)
| |
Collapse
|
3
|
Lebar AM, Velikonja A, Kramar P, Iglič A. Internal configuration and electric potential in planar negatively charged lipid head group region in contact with ionic solution. Bioelectrochemistry 2016; 111:49-56. [PMID: 27209203 DOI: 10.1016/j.bioelechem.2016.04.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 04/19/2016] [Accepted: 04/19/2016] [Indexed: 11/17/2022]
Abstract
The lipid bilayer composed of negatively charged lipid 1-palmitoyl-3-oleoyl-sn-glycero-3-phosphatidylserine (POPS) in contact with an aqueous solution of monovalent salt ions was studied theoretically by using the mean-field modified Langevin-Poisson-Boltzmann (MLPB) model. The MLPB results were tested by using molecular dynamic (MD) simulations. In the MLPB model the charge distribution of POPS head groups is theoretically described by the negatively charged surface which accounts for negatively charged phosphate groups, while the positively charged amino groups and negatively charged carboxylate groups are assumed to be fixed on the rod-like structures with rotational degree of freedom. The spatial variation of relative permittivity, which is not considered in the well-known Gouy-Chapman (GC) model or in MD simulations, is thoroughly derived within a strict statistical mechanical approach. Therefore, the spatial dependence and magnitude of electric potential within the lipid head group region and its close vicinity are considerably different in the MLPB model from the GC model. The influence of the bulk salt concentration and temperature on the number density profiles of counter-ions and co-ions in the lipid head group region and aqueous solution along with the probability density function for the lipid head group orientation angle was compared and found to be in qualitative agreement in the MLPB and MD models.
Collapse
Affiliation(s)
- Alenka Maček Lebar
- Laboratory of Biocybernetics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Aljaž Velikonja
- Laboratory of Biocybernetics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Peter Kramar
- Laboratory of Biocybernetics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia
| | - Aleš Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia.
| |
Collapse
|
4
|
Gongadze E, Iglič A. Asymmetric size of ions and orientational ordering of water dipoles in electric double layer model - an analytical mean-field approach. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.07.179] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
5
|
Disalvo E, Pinto O, Martini M, Bouchet A, Hollmann A, Frías M. Functional role of water in membranes updated: A tribute to Träuble. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1552-62. [DOI: 10.1016/j.bbamem.2015.03.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 03/20/2015] [Accepted: 03/26/2015] [Indexed: 11/30/2022]
|
6
|
Abstract
It is commonly assumed that the structure of water at a lipid-water interface is influenced mostly in the first hydration layer. However, recent results from different experimental methods show that perturbation extends through several hydration layers. Due to its low light penetration depth, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is specifically suited to study interlamellar water structure in multibilayers. Results obtained by this technique confirm the long-range water structure disturbance. Consequently, in confined membrane environments nearly all water molecules can be perturbed. It is important to note that the behavior of confined water molecules differs significantly in samples prepared in excess water and in partially hydrated samples. We show in what manner the interlamellar water perturbation is influenced by the hydration level and how it is sequentially modified with a step-by-step dehydration of samples either by water evaporation or by osmotic pressure. Our results also indicate that besides different levels of hydration the lipid-water interaction is modulated by different lipid headgroups and different lipid phases as well. Therefore, modification of interlamellar water properties may clarify the role of water-mediated effects in biological processes.
Collapse
Affiliation(s)
- Zoran Arsov
- Laboratory of Biophysics, Department of Solid State Physics, "Jozef Stefan" Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
| |
Collapse
|
7
|
Gongadze E, Velikonja A, Perutkova Š, Kramar P, Maček-Lebar A, Kralj-Iglič V, Iglič A. Ions and water molecules in an electrolyte solution in contact with charged and dipolar surfaces. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.07.147] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
8
|
Santhosh PB, Velikonja A, Perutkova Š, Gongadze E, Kulkarni M, Genova J, Eleršič K, Iglič A, Kralj-Iglič V, Ulrih NP. Influence of nanoparticle-membrane electrostatic interactions on membrane fluidity and bending elasticity. Chem Phys Lipids 2013; 178:52-62. [PMID: 24309194 DOI: 10.1016/j.chemphyslip.2013.11.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/21/2013] [Accepted: 11/22/2013] [Indexed: 11/18/2022]
Abstract
The aim of this work is to investigate the effect of electrostatic interactions between the nanoparticles and the membrane lipids on altering the physical properties of the liposomal membrane such as fluidity and bending elasticity. For this purpose, we have used nanoparticles and lipids with different surface charges. Positively charged iron oxide (γ-Fe2O3) nanoparticles, neutral and negatively charged cobalt ferrite (CoFe2O4) nanoparticles were encapsulated in neutral lipid 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine lipid mixture. Membrane fluidity was assessed through the anisotropy measurements using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Though the interaction of both the types of nanoparticles reduced the membrane fluidity, the results were more pronounced in the negatively charged liposomes encapsulated with positively charged iron oxide nanoparticles due to strong electrostatic attractions. X-ray photoelectron spectroscopy results also confirmed the presence of significant quantity of positively charged iron oxide nanoparticles in negatively charged liposomes. Through thermally induced shape fluctuation measurements of the giant liposomes, a considerable reduction in the bending elasticity modulus was observed for cobalt ferrite nanoparticles. The experimental results were supported by the simulation studies using modified Langevin-Poisson-Boltzmann model.
Collapse
Affiliation(s)
- Poornima Budime Santhosh
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
| | - Aljaž Velikonja
- Laboratory of Biocybernetics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia; SMARTEH Research and Development of Electronic Controlling and Regulating Systems, Trg Tigrovcev 1, SI-5220 Tolmin, Slovenia
| | - Šarka Perutkova
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia; Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Lipičeva 2, SI-1000 Ljubljana, Slovenia
| | - Ekaterina Gongadze
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia
| | - Mukta Kulkarni
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia
| | - Julia Genova
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
| | | | - Aleš Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, SI-1000 Ljubljana, Slovenia
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Vrazov trg 2, SI-1000 Ljubljana, Slovenia
| | - Nataša Poklar Ulrih
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia; Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CipKeBiP), Jamova 39, SI-1000 Ljubljana, Slovenia.
| |
Collapse
|
9
|
The quadrupole moment of water molecules and the permittivity of water near a charged surface. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.07.126] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
10
|
Disalvo EA, Bouchet AM, Frias MA. Connected and isolated CH2 populations in acyl chains and its relation to pockets of confined water in lipid membranes as observed by FTIR spectrometry. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1683-9. [PMID: 23500348 DOI: 10.1016/j.bbamem.2013.02.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 01/15/2013] [Accepted: 02/13/2013] [Indexed: 11/18/2022]
Abstract
Analysis of the band corresponding to the frequency of vibrational symmetric stretching mode of methylene groups in the lipid acyl chains and the bands of water below and above the phase transition of different lipids by Fourier transform infrared spectroscopy gives strong support to the formation of confined water pockets in between the lipid acyl chains. Our measures and analysis consolidate the mechanism early proposed by Traüble, in the sense that water is present in kinks formed by trans-gauche isomers along the hydrocarbon tails. The formation of these regions depends on the acyl lipid composition, which determines the presence of different populations of water species, characterized by its degree of H bond coordination in fluid saturated or unsaturated lipids. The free energy excess due to the reinforcement of the water structure along few water molecules in the adjacencies of exposed membrane residues near the phase transition is a reasonable base to explain the insertion and translocation of polar peptides and amino acid residues through the biomembrane on thermodynamic and structural grounds.
Collapse
Affiliation(s)
- E A Disalvo
- Universidad Nacional de Santiago del Estero, Santiago del Estero, Argentina.
| | | | | |
Collapse
|
11
|
Water defects induced by expansion and electrical fields in DMPC and DMPE monolayers: Contribution of hydration and confined water. Colloids Surf B Biointerfaces 2013; 102:871-8. [DOI: 10.1016/j.colsurfb.2012.09.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/12/2012] [Accepted: 09/17/2012] [Indexed: 11/19/2022]
|
12
|
Mills M, Orr BG, Banaszak Holl MM, Andricioaei I. Attractive hydration forces in DNA-dendrimer interactions on the nanometer scale. J Phys Chem B 2013; 117:973-81. [PMID: 23234339 PMCID: PMC3633417 DOI: 10.1021/jp309616t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The energetic contribution of attractive hydration forces arising from water ordering is an interesting but often neglected aspect of macromolecular interactions. Ordering effects of water can bring about cooperativity in many intermolecular transactions, in both the short and long range. Given its high charge density, this is of particular importance for DNA. For instance, in nanotechnology, highly charged dendrimers are used for DNA compaction and transfection. Hypothesizing that water ordering and hydration forces should be maximal for DNA complexes that show charge complementarity (positive-negative), we present here an analysis of water ordering from molecular dynamics simulations and free energy calculations of the interaction between DNA and a nanoparticle with a high positive charge density. Our results indicate not only that complexation of the dendrimer with DNA affects the local water structure but also that ordered water molecules facilitate long-range interactions between the molecules. This contributes significantly to the free energy of binding of dendrimers to DNA and extends the interaction well beyond the electrostatic range of the DNA. Such water effects are of potentially substantial importance in cases when molecules appear to recognize each other across sizable distances, or for which kinetic rates are too fast to be due to pure diffusion. Our results are in good agreement with experiments on the role of solvent in DNA condensation by multivalent cations and exemplify a microscopic realization of mean-field phenomenological theories for hydration forces between mesoscopic surfaces.
Collapse
|
13
|
Gongadze E, van Rienen U, Kralj-Iglič V, Iglič A. Spatial variation of permittivity of an electrolyte solution in contact with a charged metal surface: a mini review. Comput Methods Biomech Biomed Engin 2012; 16:463-80. [PMID: 22263808 PMCID: PMC3664910 DOI: 10.1080/10255842.2011.624769] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/14/2011] [Indexed: 11/14/2022]
Abstract
Contact between a charged metal surface and an electrolyte implies a particular ion distribution near the charged surface, i.e. the electrical double layer. In this mini review, different mean-field models of relative (effective) permittivity are described within a simple lattice model, where the orientational ordering of water dipoles in the saturation regime is taken into account. The Langevin-Poisson-Boltzmann (LPB) model of spatial variation of the relative permittivity for point-like ions is described and compared to a more general Langevin-Bikerman (LB) model of spatial variation of permittivity for finite-sized ions. The Bikerman model and the Poisson-Boltzmann model are derived as limiting cases. It is shown that near the charged surface, the relative permittivity decreases due to depletion of water molecules (volume-excluded effect) and orientational ordering of water dipoles (saturation effect). At the end, the LPB and LB models are generalised by also taking into account the cavity field.
Collapse
Affiliation(s)
- E. Gongadze
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - U. van Rienen
- Faculty of Computer Science and Electrical Engineering, University of Rostock, Rostock, Germany
| | - V. Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - A. Iglič
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| |
Collapse
|
14
|
Gongadze E, Iglič A. Decrease of permittivity of an electrolyte solution near a charged surface due to saturation and excluded volume effects. Bioelectrochemistry 2011; 87:199-203. [PMID: 22209491 DOI: 10.1016/j.bioelechem.2011.12.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 10/22/2011] [Accepted: 12/01/2011] [Indexed: 11/17/2022]
Abstract
The dipole moment of a water molecule in liquid water differs from that of an isolated one because each molecule is further polarized by the electric field of its neighbours. In this work a formula for the spatial dependence of the relative permittivity of an electrolyte near a highly charged surface is obtained in which the mutual influence of the water molecules is taken into account by means of the cavity field. The orientational ordering of water dipoles is considered in the saturation regime. It is predicted that the relative permittivity of an electrolyte solution near the highly charged surface (i.e. in saturation regime) may be substantially decreased due to orientational ordering of water (saturation effect) and depletion of water molecules (excluded volume effect) due to accumulation of counterions.
Collapse
Affiliation(s)
- Ekaterina Gongadze
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | | |
Collapse
|
15
|
Gongadze E, Kabaso D, Bauer S, Slivnik T, Schmuki P, van Rienen U, Iglič A. Adhesion of osteoblasts to a nanorough titanium implant surface. Int J Nanomedicine 2011; 6:1801-16. [PMID: 21931478 PMCID: PMC3173045 DOI: 10.2147/ijn.s21755] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This work considers the adhesion of cells to a nanorough titanium implant surface with sharp edges. The basic assumption was that the attraction between the negatively charged titanium surface and a negatively charged osteoblast is mediated by charged proteins with a distinctive quadrupolar internal charge distribution. Similarly, cation-mediated attraction between fibronectin molecules and the titanium surface is expected to be more efficient for a high surface charge density, resulting in facilitated integrin mediated osteoblast adhesion. We suggest that osteoblasts are most strongly bound along the sharp convex edges or spikes of nanorough titanium surfaces where the magnitude of the negative surface charge density is the highest. It is therefore plausible that nanorough regions of titanium surfaces with sharp edges and spikes promote the adhesion of osteoblasts.
Collapse
Affiliation(s)
- Ekaterina Gongadze
- Institute of General Electrical Engineering, University of Rostock, Rostock, Germany
| | | | | | | | | | | | | |
Collapse
|
16
|
Iglic A, Gongadze E, Bohinc K. Excluded volume effect and orientational ordering near charged surface in solution of ions and Langevin dipoles. Bioelectrochemistry 2010; 79:223-7. [PMID: 20678740 DOI: 10.1016/j.bioelechem.2010.05.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 05/09/2010] [Accepted: 05/18/2010] [Indexed: 11/18/2022]
Abstract
The influence of a finite volume of ions and orientational ordering of water Langevin dipoles on the dielectric permittivity profile in the vicinity of charged surface is studied theoretically via a numerical solution of the modified Poisson-Boltzmann equation. It is shown that the dielectric permittivity profile close to the charged surface is mainly determined by two mechanisms; specifically, the depletion of dipoles at the charged surface due to accumulated counterions and the increased orientational ordering of the water dipoles.
Collapse
Affiliation(s)
- Ales Iglic
- Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, SI-1000 Ljubljana, Slovenia.
| | | | | |
Collapse
|