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Trefalt G, Behrens SH, Borkovec M. Charge Regulation in the Electrical Double Layer: Ion Adsorption and Surface Interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:380-400. [PMID: 26599980 DOI: 10.1021/acs.langmuir.5b03611] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Charge regulation in the electrical double layer has important implications for ion adsorption, interparticle forces, colloidal stability, and deposition phenomena. Although charge regulation generally receives little attention, its consequences can be major, especially when considering interactions between unequally charged surfaces. The present article discusses common approaches to quantify such phenomena, especially within classical Poisson-Boltzmann theory, and pinpoints numerous situations where a consideration of charge regulation is essential. For the interpretation of interaction energy profiles, we advocate the use of the constant regulation approximation, which summarizes the surface properties in terms of two quantities, namely, the diffuse layer potential and the regulation parameter. This description also captures some pronounced regulation effects observed in the presence of multivalent ions.
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Affiliation(s)
- Gregor Trefalt
- Department of Inorganic and Analytical Chemistry, University of Geneva , Sciences II, 30 Quai Ernest-Ansermet, 1205 Geneva, Switzerland
| | - Sven Holger Behrens
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0100, United States
| | - Michal Borkovec
- Department of Inorganic and Analytical Chemistry, University of Geneva , Sciences II, 30 Quai Ernest-Ansermet, 1205 Geneva, Switzerland
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Hernando-Pérez M, Cartagena-Rivera AX, Lošdorfer Božič A, Carrillo PJP, San Martín C, Mateu MG, Raman A, Podgornik R, de Pablo PJ. Quantitative nanoscale electrostatics of viruses. NANOSCALE 2015; 7:17289-98. [PMID: 26228582 DOI: 10.1039/c5nr04274g] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Electrostatics is one of the fundamental driving forces of the interaction between biomolecules in solution. In particular, the recognition events between viruses and host cells are dominated by both specific and non-specific interactions and the electric charge of viral particles determines the electrostatic force component of the latter. Here we probe the charge of individual viruses in liquid milieu by measuring the electrostatic force between a viral particle and the Atomic Force Microscope tip. The force spectroscopy data of co-adsorbed ϕ29 bacteriophage proheads and mature virions, adenovirus and minute virus of mice capsids is utilized for obtaining the corresponding density of charge for each virus. The systematic differences of the density of charge between the viral particles are consistent with the theoretical predictions obtained from X-ray structural data. Our results show that the density of charge is a distinguishing characteristic of each virus, depending crucially on the nature of the viral capsid and the presence/absence of the genetic material.
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Affiliation(s)
- M Hernando-Pérez
- Departamento de Física de la Materia Condensada and Condensed Matter Physics Center - IFIMAC, Universidad Autónoma de Madrid, Spain.
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Angelescu DG, Caragheorgheopol D. Influence of the shell thickness and charge distribution on the effective interaction between two like-charged hollow spheres. J Chem Phys 2015; 143:144902. [DOI: 10.1063/1.4932372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Daniel G. Angelescu
- Romanian Academy, “Ilie Murgulescu” Institute of Physical Chemistry, Splaiul Independentei 202, 060021 Bucharest, Romania
| | - Dan Caragheorgheopol
- Romanian Academy, “Ilie Murgulescu” Institute of Physical Chemistry, Splaiul Independentei 202, 060021 Bucharest, Romania
- Technical University of Civil Engineering Bucharest, Lacul Tei Blvd., 122-124, 020396 Bucharest, Romania
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Tubiana L, Božič AL, Micheletti C, Podgornik R. Synonymous mutations reduce genome compactness in icosahedral ssRNA viruses. Biophys J 2015; 108:194-202. [PMID: 25564866 DOI: 10.1016/j.bpj.2014.10.070] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/29/2014] [Accepted: 10/08/2014] [Indexed: 12/15/2022] Open
Abstract
Recent studies have shown that single-stranded (ss) viral RNAs fold into more compact structures than random RNA sequences with similar chemical composition and identical length. Based on this comparison, it has been suggested that wild-type viral RNA may have evolved to be atypically compact so as to aid its encapsidation and assist the viral assembly process. To further explore the compactness selection hypothesis, we systematically compare the predicted sizes of >100 wild-type viral sequences with those of their mutants, which are evolved in silico and subject to a number of known evolutionary constraints. In particular, we enforce mutation synonynimity, preserve the codon-bias, and leave untranslated regions intact. It is found that progressive accumulation of these restricted mutations still suffices to completely erase the characteristic compactness imprint of the viral RNA genomes, making them in this respect physically indistinguishable from randomly shuffled RNAs. This shows that maintaining the physical compactness of the genome is indeed a primary factor among ssRNA viruses' evolutionary constraints, contributing also to the evidence that synonymous mutations in viral ssRNA genomes are not strictly neutral.
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Affiliation(s)
- Luca Tubiana
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia.
| | - Anže Lošdorfer Božič
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia; Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Rudolf Podgornik
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia; Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; Department of Physics, University of Massachusetts, Amherst, Massachusetts
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55
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Arzenšek D, Kuzman D, Podgornik R. Hofmeister Effects in Monoclonal Antibody Solution Interactions. J Phys Chem B 2015. [DOI: 10.1021/acs.jpcb.5b02459] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Dejan Arzenšek
- Sandoz Biopharmaceuticals
Mengeš, Lek Pharmaceuticals d.d., Kolodvorska 27, Mengeš SI-1234, Slovenia
- Netica storitve
d.o.o., Reteče 97, Škofja Loka SI-4220, Slovenia
- Department
of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, Ljubljana SI-1000, Slovenia
| | - Drago Kuzman
- Sandoz Biopharmaceuticals
Mengeš, Lek Pharmaceuticals d.d., Kolodvorska 27, Mengeš SI-1234, Slovenia
| | - Rudolf Podgornik
- Department
of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, Ljubljana SI-1000, Slovenia
- Department
of Theoretical Physics, J. Stefan Institute, Jamova cesta 39, Ljubljana SI-1000, Slovenia
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Adžić N, Podgornik R. Charge regulation in ionic solutions: thermal fluctuations and Kirkwood-Schumaker interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022715. [PMID: 25768539 DOI: 10.1103/physreve.91.022715] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Indexed: 06/04/2023]
Abstract
We study the behavior of two macroions with dissociable charge groups, regulated by local variables such as pH and electrostatic potential, immersed in a monovalent salt solution, considering cases where the net charge can either change sign or remain of the same sign depending on these local parameters. The charge regulation in both cases is described by the proper free-energy function for each of the macroions, while the coupling between the charges is evaluated on the approximate Debye-Hückel level. The charge correlation functions and the ensuing charge fluctuation forces are calculated analytically and numerically. Strong attraction between like-charged macroions is found close to the point of zero charge, specifically due to asymmetric, anticorrelated charge fluctuations of the macroion charges. The general theory is then implemented for a system of two proteinlike macroions, generalizing the form and magnitude of the Kirkwood-Schumaker interaction.
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Affiliation(s)
- Nataša Adžić
- Department of Theoretical Physics, J. Stefan Institute, 1000 Ljubljana, Slovenia
| | - Rudolf Podgornik
- Department of Theoretical Physics, J. Stefan Institute, 1000 Ljubljana, Slovenia
- Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
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Abstract
A molecular theory to study the properties of end-tethered polymer layers, in which the polymers have the ability to form hydrogen bonds with water, is presented. The approach combines the ideas of the single-chain mean-field theory to treat tethered layers with the approach of Dormidontova (Macromolecules, 2002, 35, 987.) to include hydrogen bonds. The generalization includes the consideration of position-dependent polymer-water and water-water hydrogen bonds. The theory is applied to model poly(ethylene oxide) (PEO), and the predictions are compared with equivalent polymer layers that do not form hydrogen bonds. It is found that increasing the temperature lowers the solubility of the PEO and results in a collapse of the layer at high enough temperatures. The properties of the layer and their temperature dependence are shown to be the result of the coupling between the conformational entropy of the chains, the ability of the polymer to form hydrogen bonds, and the intermolecular interactions. The structural and thermodynamic properties of the PEO layers, such as the lateral pressure-area isotherms and polymer chemical potentials, are studied as a function of temperature and type of tethering surface. The possibility of phase separation of the PEO layer at high enough temperature is predicted due to the reduced solubility induced by breaking of polymer-water hydrogen bonds. A discussion of the advantages and limitations of the theory, together with how to apply the approach to different hydrogen-bonding polymers, is presented.
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Affiliation(s)
- Chun-Lai Ren
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, USA
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