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Blanco PM, Narambuena CF, Madurga S, Mas F, Garcés JL. Unusual Aspects of Charge Regulation in Flexible Weak Polyelectrolytes. Polymers (Basel) 2023; 15:2680. [PMID: 37376324 DOI: 10.3390/polym15122680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/07/2023] [Accepted: 06/10/2023] [Indexed: 06/29/2023] Open
Abstract
This article reviews the state of the art of the studies on charge regulation (CR) effects in flexible weak polyelectrolytes (FWPE). The characteristic of FWPE is the strong coupling of ionization and conformational degrees of freedom. After introducing the necessary fundamental concepts, some unconventional aspects of the the physical chemistry of FWPE are discussed. These aspects are: (i) the extension of statistical mechanics techniques to include ionization equilibria and, in particular, the use of the recently proposed Site Binding-Rotational Isomeric State (SBRIS) model, which allows the calculation of ionization and conformational properties on the same foot; (ii) the recent progresses in the inclusion of proton equilibria in computer simulations; (iii) the possibility of mechanically induced CR in the stretching of FWPE; (iv) the non-trivial adsorption of FWPE on ionized surfaces with the same charge sign as the PE (the so-called "wrong side" of the isoelectric point); (v) the influence of macromolecular crowding on CR.
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Affiliation(s)
- Pablo M Blanco
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Claudio F Narambuena
- Grupo de Bionanotecnologia y Sistemas Complejos, Infap-CONICET & Facultad Regional San Rafael, Universidad Tecnológica Nacional, San Rafael 5600, Argentina
| | - Sergio Madurga
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Francesc Mas
- Physical Chemistry Unit, Materials Science and Physical Chemistry Department & Research Institute of Theoretical and Computational Chemistry (IQTCUB), Barcelona University (UB), 08028 Barcelona, Catalonia, Spain
| | - Josep L Garcés
- Chemistry Department, Technical School of Agricultural Engineering & AGROTECNIO, Lleida University (UdL), 25003 Lleida, Catalonia, Spain
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2
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Lu D, Fatehi P. Interaction of rough ellipsoidal particles with random surface asperities in colloidal systems. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.117869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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3
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Malicka W, Haag R, Ballauff M. Interaction of Heparin with Proteins: Hydration Effects. J Phys Chem B 2022; 126:6250-6260. [PMID: 35960645 DOI: 10.1021/acs.jpcb.2c04928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a thermodynamic investigation of the interaction of heparin with lysozyme in the presence of potassium glutamate (KGlu). The binding constant Kb is measured by isothermal titration calorimetry (ITC) in a temperature range from 288 to 310 K for concentrations of KGlu between 25 and 175 mM. The free energy of binding ΔGb derived from Kb is strongly decreasing with increasing concentration of KGlu, whereas the dependence of ΔGb on temperature T is found to be small. The decrease of ΔGb can be explained in terms of counterion release: Binding of lysozyme to the strong polyelectrolyte heparin liberates approximately three of the condensed counterions of heparin, thus increasing the entropy of the system. The dependence of ΔGb on T, on the other hand, is traced back to a change of hydration of the protein and the polyelectrolyte upon complex formation. This dependence is quantitatively described by the parameter Δw that depends on T and vanishes at a characteristic temperature T0. A comparison of the complex formation in the presence of KGlu with the one in the presence of NaCl demonstrates that the parameters related to hydration are changed considerably. The characteristic temperature T0 in the presence of KGlu solutions is considerably smaller than that in the presence of NaCl solutions. The change of specific heat Δcp is found to become more negative with increasing salt concentration: This finding agrees with the model-free analysis by the generalized van't Hoff equation. The entire analysis reveals a small but important change of the free energy of binding by hydration. It shows that these ion-specific Hofmeister effects can be modeled quantitatively in terms of a characteristic temperature T0 and a parameter describing the dependence of Δcp on salt concentration.
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Affiliation(s)
- Weronika Malicka
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Rainer Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany
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4
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Lunkad R, Barroso da Silva FL, Košovan P. Both Charge-Regulation and Charge-Patch Distribution Can Drive Adsorption on the Wrong Side of the Isoelectric Point. J Am Chem Soc 2022; 144:1813-1825. [DOI: 10.1021/jacs.1c11676] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Raju Lunkad
- Department of Physical and Macromolecular Chemistry, Charles University, Hlavova 8, 128 43 Prague, Czech Republic
| | - Fernando L. Barroso da Silva
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
- Department of Biomolecular Sciences, School of Pharmaceutical Sciences at Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo 14040-900, Brazil
| | - Peter Košovan
- Department of Physical and Macromolecular Chemistry, Charles University, Hlavova 8, 128 43 Prague, Czech Republic
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Mahapatra S, Polimeni M, Gentiluomo L, Roessner D, Frieß W, Peters GHJ, Streicher WW, Lund M, Harris P. Self-Interactions of Two Monoclonal Antibodies: Small-Angle X-ray Scattering, Light Scattering, and Coarse-Grained Modeling. Mol Pharm 2021; 19:508-519. [PMID: 34939811 DOI: 10.1021/acs.molpharmaceut.1c00627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using light scattering (LS), small-angle X-ray scattering (SAXS), and coarse-grained Monte Carlo (MC) simulations, we studied the self-interactions of two monoclonal antibodies (mAbs), PPI03 and PPI13. With LS measurements, we obtained the osmotic second virial coefficient, B22, and the molecular weight, Mw, of the two mAbs, while with SAXS measurements, we studied the mAbs' self-interaction behavior in the high protein concentration regime up to 125 g/L. Through SAXS-derived coarse-grained representations of the mAbs, we performed MC simulations with either a one-protein or a two-protein model to predict B22. By comparing simulation and experimental results, we validated our models and obtained insights into the mAbs' self-interaction properties, highlighting the role of both ion binding and charged patches on the mAb surfaces. Our models provide useful information about mAbs' self-interaction properties and can assist the screening of conditions driving to colloidal stability.
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Affiliation(s)
- Sujata Mahapatra
- Novozymes A/S, Biologiens Vej 2, 2800 Kgs. Lyngby, Denmark.,Department of Chemistry, Technical University of Denmark, Kemitorvet Building 207, 2800 Kgs. Lyngby, Denmark
| | - Marco Polimeni
- Division of Theoretical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, 223 62 Lund, Sweden
| | - Lorenzo Gentiluomo
- Wyatt Technology Europe GmbH, Hochstrasse 12a, 56307 Dernbach, Germany.,Department of Pharmacy, Pharmaceutical Technology and Biopharmaceutics, Ludwig Maximilians-Universität München, Butenandtstrasse 5, 81377 Munich, Germany
| | - Dierk Roessner
- Wyatt Technology Europe GmbH, Hochstrasse 12a, 56307 Dernbach, Germany
| | - Wolfgang Frieß
- Department of Pharmacy, Pharmaceutical Technology and Biopharmaceutics, Ludwig Maximilians-Universität München, Butenandtstrasse 5, 81377 Munich, Germany
| | - Günther H J Peters
- Department of Chemistry, Technical University of Denmark, Kemitorvet Building 207, 2800 Kgs. Lyngby, Denmark
| | | | - Mikael Lund
- Division of Theoretical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, 223 62 Lund, Sweden.,Advanced X-ray and Neutron Science (LINXS), Lund University, Scheelevägen 19, 22370 Lund, Sweden
| | - Pernille Harris
- Department of Chemistry, Technical University of Denmark, Kemitorvet Building 207, 2800 Kgs. Lyngby, Denmark
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6
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Polyelectrolyte-nanoparticle mutual charge regulation and its influence on their complexation. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127258] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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7
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Shahfar H, Forder JK, Roberts CJ. Toward a Suite of Coarse-Grained Models for Molecular Simulation of Monoclonal Antibodies and Therapeutic Proteins. J Phys Chem B 2021; 125:3574-3588. [PMID: 33821645 DOI: 10.1021/acs.jpcb.1c01903] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of coarse-grained models for molecular simulation of proteins are considered, with emphasis on the application of predicting protein-protein self-interactions for monoclonal antibodies (MAbs). As an illustrative example and for quantitative comparison, the models are used to predict osmotic virial coefficients over a broad range of attractive and repulsive self-interactions and solution conditions for a series of MAbs where the second osmotic virial coefficient has been experimentally determined in prior work. The models are compared based on how well they can predict experimental behavior, their computational burdens, and scalability. An intermediate-resolution model is also introduced that can capture specific electrostatic interactions with improved efficiency and similar or improved accuracy when compared to the previously published models. Guidance is included for the selection of coarse-grained models more generally for capturing a balance of electrostatic, steric, and short-ranged nonelectrostatic interactions for proteins from low to high concentrations.
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Affiliation(s)
- Hassan Shahfar
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States.,Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, United States
| | - James K Forder
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Christopher J Roberts
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
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8
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Lu D, Fatehi P. A modeling approach for quantitative assessment of interfacial interaction between two rough particles in colloidal systems. J Colloid Interface Sci 2020; 587:24-38. [PMID: 33360896 DOI: 10.1016/j.jcis.2020.11.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 11/29/2020] [Accepted: 11/30/2020] [Indexed: 01/21/2023]
Abstract
HYPOTHESIS AND BACKGROUND The simulation of rough particle surface is important to understand and control the interface behavior of particles in colloidal systems. Literature analysis suggested a lack of information for an accurate model simulating the interfacial interaction between two rough particles. It is hypothesized that the total interfacial energy developed between two rough particles would depend on the surface morphologies of particles, and it could be predicted if a mathematical model to represent the interaction of two rough particles were created accurately. EXPERIMENTS In this study, mathematical models were developed to determine the interfacial energy created between two particles according to the XDLVO theory by considering the rippled particle theory and surface element integral (SEI) method. Three different scenarios of particle interactions were assumed in the simulation. The present study provides deep insights into particle interactions via considering aspect ratio, size, and surface roughness of two particles in colloidal systems. FINDINGS The assessment of the interfacial interaction revealed that an increase in the aspect ratio, surface roughness, and relative surface roughness of particles would weaken the total interaction energy generated between particles and promote particle aggregation. Increased interaction energy was predicted for the interaction of particles by increasing the particle size. The asperity ratio was more effective than the asperity number in controlling the interfacial energy between two particles. The results of this study could be used for foreseeing the interaction of rough particles, which has a significant application in particle coagulation or dispersion in colloidal systems.
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Affiliation(s)
- Duowei Lu
- Green Processes Research Centre and Chemical Engineering Department, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B5E1, Canada
| | - Pedram Fatehi
- Green Processes Research Centre and Chemical Engineering Department, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B5E1, Canada.
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9
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Merzougui CE, Roblin P, Aimar P, Venault A, Chang Y, Causserand C, Bacchin P. Pearl-necklace assembly of human serum albumin with the poly(acrylic acid) polyelectrolyte investigated using small angle X-ray scattering (SAXS). SOFT MATTER 2020; 16:9964-9974. [PMID: 33034602 DOI: 10.1039/d0sm01221a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this comprehensive study, the interaction of human serum albumin (HSA) with poly(acrylic acid) (PAA) was explored using small angle X-ray scattering (SAXS) combined with chromatography. The results revealed the formation of a complex between HSA macromolecules and PAA chains but solely under some specific conditions of the ionic strength and pH of the medium. In fact, this binding was found to take place only at pH close to 5 and at low ionic strength (0.15 M). Otherwise, for a higher pH and a salt concentration of 0.75 M the HSA-PAA complex tends to dissociate completely showing the reversibility of the complexation. The assessment of the influence of the HSA/PAA molar ratio on the radius of gyration of the complex suggests that 4 HSA molecules could bind to each 100 kDa PAA chain. In addition, the Porod volume evaluation for the same range of the HSA/PAA ratio confirms this assumption. Finally, an all-atom SAXS modelling study using the BUNCH program was conducted to find a compatible model that fits the HSA-PAA complex scattering data. This model allows us to portray the HSA/PAA complex as a pearl-necklace assembly with 4 HSA molecules on the 100 kDa PAA chain.
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Affiliation(s)
- Charaf E Merzougui
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Pierre Roblin
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Pierre Aimar
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Antoine Venault
- R&D Center for Membrane Technology, Chung Yuan Christian University, Chung Li, Taiwan
| | - Yung Chang
- R&D Center for Membrane Technology, Chung Yuan Christian University, Chung Li, Taiwan
| | - Christel Causserand
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
| | - Patrice Bacchin
- Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.
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10
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Srivastava R, Chattopadhyaya M, Bandyopadhyay P. Calculation of salt-dependent free energy of binding of β-lactoglobulin homodimer formation and mechanism of dimer formation using molecular dynamics simulation and three-dimensional reference interaction site model (3D-RISM): diffuse salt ions and non-polar interactions between the monomers favor the dimer formation. Phys Chem Chem Phys 2020; 22:2142-2156. [PMID: 31912070 DOI: 10.1039/c9cp05578a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
There are several important phenomena in chemistry, biology, and physics where molecules (or parts of a molecule) having charges of the same sign come closer together and become stable. DNA condensation, RNA folding, colloid-colloid interactions are some of the examples of this kind. In the current work, we have investigated how β-lactoglobulin, a protein found in milk, in spite of carrying +13 charge, favors the homodimer formation in the presence of salt. We have focussed on calculating the protein-protein binding free energy in the presence of salt and identifying the thermodynamic and microscopic mechanism of the process. Estimation of binding free energy of this salt-dependent process is done by combining molecular dynamics simulation with statistical mechanical theory of three-dimensional reference interaction site model (3D-RISM). Binding free energy is evaluated from the chemical potential of the solutes as opposed to potential of mean force calculation, which gives only a constrained free energy. Our calculated values semi-quantitatively match with the experimental results. By examining the different components of binding free energy, we have found that the role of salt ions (especially of Cl-) is to shift the equilibrium towards the dimer. Non-polar (Lennard-Jones) interactions between the monomers is also favorable to the binding free energy. However, water slightly disfavors the dimer formation. For the microscopic mechanism, heterogeneous of both Na+ and Cl- near the charged residues at the binding interface and change of this charge distribution on dimer formation contribute to the stability. A fine-tuning of enthalpic and entropic effects of salt ions is found to operate at different salt concentrations. Both thermodynamic and microscopic mechanism of dimer formation gives detailed insight into the complex electrostatics of charged protein-protein binding.
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Affiliation(s)
- Rakesh Srivastava
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India.
| | | | - Pradipta Bandyopadhyay
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India.
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11
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Xu X, Angioletti-Uberti S, Lu Y, Dzubiella J, Ballauff M. Interaction of Proteins with Polyelectrolytes: Comparison of Theory to Experiment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5373-5391. [PMID: 30095921 DOI: 10.1021/acs.langmuir.8b01802] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We discuss recent investigations of the interaction of polyelectrolytes with proteins. In particular, we review our recent studies on the interaction of simple proteins such as human serum albumin (HSA) and lysozyme with linear polyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte brushes. In all cases discussed here, we combined experimental work with molecular dynamics (MD) simulations and mean-field theories. In particular, isothermal titration calorimetry (ITC) has been employed to obtain the respective binding constants Kb and the Gibbs free energy of binding. MD simulations with explicit counterions but implicit water demonstrate that counterion release is the main driving force for the binding of proteins to strongly charged polyelectrolytes: patches of positive charges located on the surface of the protein become multivalent counterions of the polyelectrolyte, thereby releasing a number of counterions condensed on the polyelectrolyte. The binding Gibbs free energy due to counterion release is predicted to scale with the logarithm of the salt concentration in the system, which is verified by both simulations and experiment. In several cases, namely, for the interaction of proteins with linear polyelectrolytes and highly charged hydrophilic dendrimers, the binding constant could be calculated from simulations to very good approximation. This finding demonstrated that in these cases explicit hydration effects do not contribute to the Gibbs free energy of binding. The Gibbs free energy can also be used to predict the kinetics of protein uptake by microgels for a given system by applying dynamic density functional theory. The entire discussion demonstrates that the direct comparison of theory with experiments can lead to a full understanding of the interaction of proteins with charged polymers. Possible implications for applications, such as drug design, are discussed.
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Affiliation(s)
- Xiao Xu
- School of Chemical Engineering , Nanjing University of Science and Technology , 200 Xiao Ling Wei , Nanjing 210094 , P. R. China
| | - Stefano Angioletti-Uberti
- Department of Materials , Imperial College London , London SW7 2AZ - UK , U.K
- International Research Centre for Soft Matter , Beijing University of Chemical Technology , 100099 Beijing , PR China
| | - Yan Lu
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institute of Chemistry , University of Potsdam , 14467 Potsdam , Germany
| | - Joachim Dzubiella
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Physikalisches Institut , Albert-Ludwigs-Universität , 79104 Freiburg , Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin , Germany
- Institut für Physik , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
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12
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Mehr FN, Grigoriev D, Puretskiy N, Böker A. Mono-patchy zwitterionic microcolloids as building blocks for pH-controlled self-assembly. SOFT MATTER 2019; 15:2430-2438. [PMID: 30788469 PMCID: PMC6430096 DOI: 10.1039/c8sm02151a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
A directional molecular interaction between microcolloids can be achieved through pre-defined sites on their surface, "patches", which might make them follow each other in a controlled way and assemble into target structures of more complexity. In this article, we report the successful generation and characterization of mono-patchy melamine-formaldehyde microparticles with oppositely charged patches made of poly(methyl vinyl ether-alt-maleic acid) or polyethyleneimine via microcontact printing. The study of their self-aggregation behavior in solution shows that by change of pH, particle dimers are formed via attractive electrostatic force between the patchy and non-patchy surface of the particles, which reaches its optimum at a specific pH.
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Affiliation(s)
- Fatemeh Naderi Mehr
- Fraunhofer Institute for Applied Polymer Research IAP
,
D-14476 Potsdam-Golm
, Germany
.
;
- Chair of Polymer Materials and Polymer Technologies
, University Potsdam
,
D-14476 Potsdam-Golm
, Germany
| | - Dmitry Grigoriev
- Fraunhofer Institute for Applied Polymer Research IAP
,
D-14476 Potsdam-Golm
, Germany
.
;
| | - Nikolay Puretskiy
- Fraunhofer Institute for Applied Polymer Research IAP
,
D-14476 Potsdam-Golm
, Germany
.
;
| | - Alexander Böker
- Fraunhofer Institute for Applied Polymer Research IAP
,
D-14476 Potsdam-Golm
, Germany
.
;
- Chair of Polymer Materials and Polymer Technologies
, University Potsdam
,
D-14476 Potsdam-Golm
, Germany
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13
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Locatelli E, Bianchi E. Tuning the order of colloidal monolayers: assembly of heterogeneously charged colloids close to a patterned substrate. SOFT MATTER 2018; 14:8119-8136. [PMID: 30283950 DOI: 10.1039/c8sm00691a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We study the behavior of negatively charged colloids with two positively charged polar caps close to a planar patterned surface. The competition between the different anisotropic components of the particle-particle interaction is able by itself to give rise to a rich assembly scenario: colloids with charged surface patterns already form different crystalline domains when adsorbed to a homogeneously charged substrate. Here we consider substrates composed of alternating (negative/neutral, positive/neutral and positive/negative) parallel stripes and, by means of Monte Carlo simulations, we investigate the ordering of the colloids on changing the number of the stripes. We show that the additional competition between the two different lengths scales characterizing the system (i.e., the particle interaction range and the size of the stripes) gives rise to a plethora of distinct particle arrangements, where some well-defined trends can be observed. By accurately tuning the substrate charged motif it is possible to, e.g., promote specific particle arrangements, disfavor crystalline domains or induce the formation of extended, open clusters.
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Affiliation(s)
- Emanuele Locatelli
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090, Vienna, Austria.
| | - Emanuela Bianchi
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090, Vienna, Austria.
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14
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Chen D, Zhang G, Torquato S. Inverse Design of Colloidal Crystals via Optimized Patchy Interactions. J Phys Chem B 2018; 122:8462-8468. [DOI: 10.1021/acs.jpcb.8b05627] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Lošdorfer BoŽič A. From discrete to continuous description of spherical surface charge distributions. SOFT MATTER 2018; 14:1149-1161. [PMID: 29345714 DOI: 10.1039/c7sm02207g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The importance of electrostatic interactions in soft matter and biological systems can often be traced to non-uniform charge effects, which are commonly described using a multipole expansion of the corresponding charge distribution. The standard approach when extracting the charge distribution of a given system is to treat the constituent charges as points. This can, however, lead to an overestimation of multipole moments of high order, such as dipole, quadrupole, and higher moments. Focusing on distributions of charges located on a spherical surface - characteristic of numerous biological macromolecules, such as globular proteins and viral capsids, as well as of inverse patchy colloids - we develop a novel way of representing spherical surface charge distributions based on the von Mises-Fisher distribution. This approach takes into account the finite spatial extension of individual charges, and leads to a simple yet powerful way of describing surface charge distributions and their multipole expansions. In this manner, we analyze charge distributions and the derived multipole moments of a number of different spherical configurations of identical charges with various degrees of symmetry. We show how the number of charges, their size, and the geometry of their configuration influence the behavior and relative importance of multipole magnitudes of different order. Importantly, we clearly demonstrate how neglecting the effect of charge size leads to an overestimation of high-order multipoles. The results of our work can be applied to construct analytical models of electrostatic interactions and multipole expansion of charged particles in diverse soft matter and biological systems.
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16
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Lošdorfer Božič A, Podgornik R. pH Dependence of Charge Multipole Moments in Proteins. Biophys J 2017; 113:1454-1465. [PMID: 28978439 DOI: 10.1016/j.bpj.2017.08.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 08/10/2017] [Accepted: 08/11/2017] [Indexed: 11/26/2022] Open
Abstract
Electrostatic interactions play a fundamental role in the structure and function of proteins. Due to ionizable amino acid residues present on the solvent-exposed surfaces of proteins, the protein charge is not constant but varies with the changes in the environment-most notably, the pH of the surrounding solution. We study the effects of pH on the charge of four globular proteins by expanding their surface charge distributions in terms of multipoles. The detailed representation of the charges on the proteins is in this way replaced by the magnitudes and orientations of the multipole moments of varying order. Focusing on the three lowest-order multipoles-the total charge, dipole, and quadrupole moment-we show that the value of pH influences not only their magnitudes, but more notably and importantly also the spatial orientation of their principal axes. Our findings imply important consequences for the study of protein-protein interactions and the assembly of both proteinaceous shells and patchy colloids with dissociable charge groups.
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Affiliation(s)
| | - Rudolf Podgornik
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia; Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
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17
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Chen J, Chevreuil M, Combet S, Lansac Y, Tresset G. Investigating the thermal dissociation of viral capsid by lattice model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:474001. [PMID: 29098985 PMCID: PMC7104912 DOI: 10.1088/1361-648x/aa8d88] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/08/2017] [Accepted: 09/19/2017] [Indexed: 06/07/2023]
Abstract
The dissociation of icosahedral viral capsids was investigated by a homogeneous and a heterogeneous lattice model. In thermal dissociation experiments with cowpea chlorotic mottle virus and probed by small-angle neutron scattering, we observed a slight shrinkage of viral capsids, which can be related to the strengthening of the hydrophobic interaction between subunits at increasing temperature. By considering the temperature dependence of hydrophobic interaction in the homogeneous lattice model, we were able to give a better estimate of the effective charge. In the heterogeneous lattice model, two sets of lattice sites represented different capsid subunits with asymmetric interaction strengths. In that case, the dissociation of capsids was found to shift from a sharp one-step transition to a gradual two-step transition by weakening the hydrophobic interaction between AB and CC subunits. We anticipate that such lattice models will shed further light on the statistical mechanics underlying virus assembly and disassembly.
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Affiliation(s)
- Jingzhi Chen
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Maelenn Chevreuil
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Sophie Combet
- Laboratoire Léon Brillouin (LLB), UMR 12 CEA-CNRS, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex, France
| | - Yves Lansac
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
- GREMAN, CNRS, Université François Rabelais, 73200 Tours, France
| | - Guillaume Tresset
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
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18
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Srivastava D, Santiso E, Gubbins K, Barroso da Silva FL. Computationally Mapping pK a Shifts Due to the Presence of a Polyelectrolyte Chain around Whey Proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11417-11428. [PMID: 28859478 DOI: 10.1021/acs.langmuir.7b02271] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Experimental studies have shown the formation of soluble complexes in the pure repulsive Coulombic regime even when the net charges of the protein and the polyelectrolyte have the same sign ( De Kruif et al. Curr. Opin. Colloid Interface Sci. 2004 , 9 , 340 ; De Vries et al. J. Chem. Phys. 2003 , 118 , 4649 ; Grymonpre et al. Biomacromolecules 2001 , 2 , 422 ; Hattori et al. Langmuir 2000 , 16 , 9738 ). This attractive phenomenon has often been described as "complexation on the wrong side of pI". While one theory assumes the existence of "charged patches" on the protein surface from ion-dipole interactions, thus allowing a polyelectrolyte to bind to an oppositely heterogeneous charged protein region, another theoretical view considers the induced-charge interactions to be the dominant factor in these complexations. This charge regulation mechanism can be described by proton fluctuations resulting from mutual rearrangements of the distributions of the charged groups, due to perturbations of the acid-base equilibrium. Using constant-pH Monte Carlo simulations and several quantitative and visual analysis tools, we investigate the significance of each of these interactions for two whey proteins, α-lactalbumin (α-LA) and lysozyme (LYZ). Through physical chemistry parameters, free energies of interactions, and the mapping of amino acid pKa shifts and polyelectrolyte trajectories, we show the charge regulation mechanism to be the most important contributor in protein-polyelectrolyte complexation regardless of pH, dipole moment, and protein capacitance in a low salt regime.
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Affiliation(s)
- Deepti Srivastava
- Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Erik Santiso
- Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Keith Gubbins
- Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Fernando Luís Barroso da Silva
- Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
- Department of Physics and Chemistry, School of Pharmaceutical Sciences at Ribeirão Preto, University of São Paulo , 14040-903 Ribeirão Preto, SP, Brazil
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19
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Adar RM, Andelman D, Diamant H. Electrostatics of patchy surfaces. Adv Colloid Interface Sci 2017; 247:198-207. [PMID: 28526129 DOI: 10.1016/j.cis.2017.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 10/19/2022]
Abstract
In the study of colloidal, biological and electrochemical systems, it is customary to treat surfaces, macromolecules and electrodes as homogeneously charged. This simplified approach is proven successful in most cases, but fails to describe a wide range of heterogeneously charged surfaces commonly used in experiments. For example, recent experiments have revealed a long-range attraction between overall neutral surfaces, locally charged in a mosaic-like structure of positively and negatively charged domains ("patches"). Here, we review experimental and theoretical studies addressing the stability of heterogeneously charged surfaces, their effect on ionic profiles in solution, and the interaction between two such surfaces. We focus on electrostatics, and highlight the important new physical parameters appearing in the heterogeneous case, such as the largest patch size and inter-surface charge correlations.
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20
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Zhou S, Zhou R. A comprehensive comparison between thermodynamic perturbation theory and first-order mean spherical approximation: Based on discrete potentials with hard core. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.05.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Bianchi E, van Oostrum PD, Likos CN, Kahl G. Inverse patchy colloids: Synthesis, modeling and self-organization. Curr Opin Colloid Interface Sci 2017. [DOI: 10.1016/j.cocis.2017.03.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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22
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Wang W, Li L, Henzler K, Lu Y, Wang J, Han H, Tian Y, Wang Y, Zhou Z, Lotze G, Narayanan T, Ballauff M, Guo X. Protein Immobilization onto Cationic Spherical Polyelectrolyte Brushes Studied by Small Angle X-ray Scattering. Biomacromolecules 2017; 18:1574-1581. [PMID: 28398743 DOI: 10.1021/acs.biomac.7b00164] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The immobilization of bovine serum albumins (BSA) onto cationic spherical polyelectrolyte brushes (SPB) consisting of a solid polystyrene (PS) core and a densely grafted poly(2-aminoethyl methacrylate hydrochloride) (PAEMH) shell was studied by small-angle X-ray scattering (SAXS). The observed dynamics of adsorption of BSA onto SPB by time-resolved SAXS can be divided into two stages. In the first stage (tens of milliseconds), the added proteins as in-between bridge instantaneously caused the aggregation of SPB. Then BSA penetrated into the brush layer driven by electrostatic attractions, and reached equilibrium in the second stage (tens of seconds). The amount of BSA immobilized onto brush layer reached the maximum when pH was increased to about 6.1 and BSA concentration to 10 g/L. The cationic SPB were confirmed to provide stronger adsorption capacity for BSA compared to anionic ones.
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Affiliation(s)
- Weihua Wang
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China.,Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Li Li
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China
| | - Katja Henzler
- Paul Scherer Institute , Laboratory for Synchrotron Radiation and Femtochemistry, 5232 Villigen PSI, Switzerland
| | - Yan Lu
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Hahn-Meitner-Platz 1, 14109 Berlin, Germany.,Institut für Phzsik, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
| | - Junyou Wang
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China
| | - Haoya Han
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China
| | - Yuchuan Tian
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China
| | - Yunwei Wang
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China
| | - Zhiming Zhou
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China
| | - Gudrun Lotze
- European Synchrotron Radiation Facility , F-38043, Grenoble, France
| | | | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Hahn-Meitner-Platz 1, 14109 Berlin, Germany.,Institut für Phzsik, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
| | - Xuhong Guo
- State-Key Laboratory of Chemical Engineering, East China University of Science and Technology , Shanghai 200237, People's Republic of China.,Engineering Research Center of Materials Chemical Engineering of Xinjiang Bingtuan, Shihezi University , Xinjiang 832000, People's Republic of China
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23
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Yigit C, Kanduč M, Ballauff M, Dzubiella J. Interaction of Charged Patchy Protein Models with Like-Charged Polyelectrolyte Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:417-427. [PMID: 27983858 DOI: 10.1021/acs.langmuir.6b03797] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study the adsorption of charged patchy particle models (CPPMs) on a thin film of a like-charged and dense polyelectrolyte (PE) brush (of 50 monomers per chain) by means of implicit-solvent, explicit-salt Langevin dynamics computer simulations. Our previously introduced set of CPPMs embraces well-defined one- and two-patched spherical globules, each of the same net charge and (nanometer) size, with mono- and multipole moments comparable to those of small globular proteins. We focus on electrostatic effects on the adsorption far away from the isoelectric point of typical proteins, i.e., where charge regulation plays no role. Despite the same net charge of the brush and globule, we observe large binding affinities up to tens of the thermal energy, kBT, which are enhanced by decreasing salt concentration and increasing charge of the patch(es). Our analysis of the distance-resolved potentials of mean force together with a phenomenological description of all leading interaction contributions shows that the attraction is strongest at the brush surface, driven by multipolar, Born (self-energy), and counterion-release contributions, dominating locally over the monopolar and steric repulsions.
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Affiliation(s)
- Cemil Yigit
- Institut für Physik, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin , 14109 Berlin, Germany
- Multifunctional Biomaterials for Medicine, Helmholtz Virtual Institute , 14513 Teltow, Germany
| | - Matej Kanduč
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin , 14109 Berlin, Germany
| | - Matthias Ballauff
- Institut für Physik, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin , 14109 Berlin, Germany
- Multifunctional Biomaterials for Medicine, Helmholtz Virtual Institute , 14513 Teltow, Germany
| | - Joachim Dzubiella
- Institut für Physik, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin , 14109 Berlin, Germany
- Multifunctional Biomaterials for Medicine, Helmholtz Virtual Institute , 14513 Teltow, Germany
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24
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Bianchi E, Capone B, Coluzza I, Rovigatti L, van Oostrum PDJ. Limiting the valence: advancements and new perspectives on patchy colloids, soft functionalized nanoparticles and biomolecules. Phys Chem Chem Phys 2017; 19:19847-19868. [DOI: 10.1039/c7cp03149a] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Artistic representation of limited valance units consisting of a soft core (in blue) and a small number of flexible bonding patches (in orange).
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Affiliation(s)
- Emanuela Bianchi
- Faculty of Physics
- University of Vienna
- A-1090 Vienna
- Austria
- Institute for Theoretical Physics
| | - Barbara Capone
- Faculty of Physics
- University of Vienna
- A-1090 Vienna
- Austria
- Dipartimento di Scienze
| | - Ivan Coluzza
- Faculty of Physics
- University of Vienna
- A-1090 Vienna
- Austria
| | - Lorenzo Rovigatti
- Faculty of Physics
- University of Vienna
- A-1090 Vienna
- Austria
- Rudolf Peierls Centre for Theoretical Physics
| | - Peter D. J. van Oostrum
- Department of Nanobiotechnology
- Institute for Biologically Inspired Materials
- University of Natural Resources and Life Sciences
- A-1190 Vienna
- Austria
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25
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Blanco MA, Shen VK. Effect of the surface charge distribution on the fluid phase behavior of charged colloids and proteins. J Chem Phys 2016; 145:155102. [PMID: 27782465 PMCID: PMC5158025 DOI: 10.1063/1.4964613] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A generic but simple model is presented to evaluate the effect of the heterogeneous surface charge distribution of proteins and zwitterionic nanoparticles on their thermodynamic phase behavior. By considering surface charges as continuous "patches," the rich set of surface patterns that is embedded in proteins and charged patchy particles can readily be described. This model is used to study the fluid phase separation of charged particles where the screening length is of the same order of magnitude as the particle size. In particular, two types of charged particles are studied: dipolar fluids and protein-like fluids. The former represents the simplest case of zwitterionic particles, whose charge distribution can be described by their dipole moment. The latter system corresponds to molecules/particles with complex surface charge arrangements such as those found in biomolecules. The results for both systems suggest a relation between the critical region, the strength of the interparticle interactions, and the arrangement of charged patches, where the critical temperature is strongly correlated to the magnitude of the dipole moment. Additionally, competition between attractive and repulsive charge-charge interactions seems to be related to the formation of fluctuating clusters in the dilute phase of dipolar fluids, as well as to the broadening of the binodal curve in protein-like fluids. Finally, a variety of self-assembled architectures are detected for dipolar fluids upon small changes to the charge distribution, providing the groundwork for studying the self-assembly of charged patchy particles.
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Affiliation(s)
- Marco A. Blanco
- National Institute of Standards and Technology, Gaithersburg, MD 20899
- Institute of Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
| | - Vincent K. Shen
- National Institute of Standards and Technology, Gaithersburg, MD 20899
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26
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Roos M, Ott M, Hofmann M, Link S, Rössler E, Balbach J, Krushelnitsky A, Saalwächter K. Coupling and Decoupling of Rotational and Translational Diffusion of Proteins under Crowding Conditions. J Am Chem Soc 2016; 138:10365-72. [PMID: 27434647 DOI: 10.1021/jacs.6b06615] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Molecular motion of biopolymers in vivo is known to be strongly influenced by the high concentration of organic matter inside cells, usually referred to as crowding conditions. To elucidate the effect of intermolecular interactions on Brownian motion of proteins, we performed (1)H pulsed-field gradient NMR and fluorescence correlation spectroscopy (FCS) experiments combined with small-angle X-ray scattering (SAXS) and viscosity measurements for three proteins, αB-crystalline (αBc), bovine serum albumin, and hen egg-white lysozyme (HEWL) in aqueous solution. Our results demonstrate that long-time translational diffusion quantitatively follows the expected increase of macro-viscosity upon increasing the protein concentration in all cases, while rotational diffusion as assessed by polarized FCS and previous multi-frequency (1)H NMR relaxometry experiments reveals protein-specific behavior spanning the full range between the limiting cases of full decoupling from (αBc) and full coupling to (HEWL) the macro-viscosity. SAXS was used to study the interactions between the proteins in solution, whereby it is shown that the three cases cover the range between a weakly interacting hard-sphere system (αBc) and screened Coulomb repulsion combined with short-range attraction (HEWL). Our results, as well as insights from the recent literature, suggest that the unusual rotational-translational coupling may be due to anisotropic interactions originating from hydrodynamic shape effects combined with high charge and possibly a patchy charge distribution.
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Affiliation(s)
- Matthias Roos
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg , 06099 Halle (Saale), Germany
| | - Maria Ott
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg , 06099 Halle (Saale), Germany
| | - Marius Hofmann
- Experimentalphysik II, Universität Bayreuth , 95440 Bayreuth, Germany
| | - Susanne Link
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg , 06099 Halle (Saale), Germany
| | - Ernst Rössler
- Experimentalphysik II, Universität Bayreuth , 95440 Bayreuth, Germany
| | - Jochen Balbach
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg , 06099 Halle (Saale), Germany
| | - Alexey Krushelnitsky
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg , 06099 Halle (Saale), Germany
| | - Kay Saalwächter
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg , 06099 Halle (Saale), Germany
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27
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Adar RM, Andelman D, Diamant H. Electrostatic attraction between overall neutral surfaces. Phys Rev E 2016; 94:022803. [PMID: 27627373 DOI: 10.1103/physreve.94.022803] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Indexed: 06/06/2023]
Abstract
Two overall neutral surfaces with positively and negatively charged domains ("patches") have been shown in recent experiments to exhibit long-range attraction when immersed in an ionic solution. Motivated by the experiments, we calculate analytically the osmotic pressure between such surfaces within the Poisson-Boltzmann framework, using a variational principle for the surface-averaged free energy. The electrostatic potential, calculated beyond the linear Debye-Hückel theory, yields an overall attraction at large intersurface separations, over a wide range of the system's controlled length scales. In particular, the attraction is stronger and occurs at smaller separations for surface patches of larger size and charge density. In this large patch limit, we find that the attraction-repulsion crossover separation is inversely proportional to the square of the patch-charge density and to the Debye screening length.
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Affiliation(s)
- Ram M Adar
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - David Andelman
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Haim Diamant
- Raymond and Beverly Sackler School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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28
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Yigit C, Heyda J, Ballauff M, Dzubiella J. Like-charged protein-polyelectrolyte complexation driven by charge patches. J Chem Phys 2016; 143:064905. [PMID: 26277164 DOI: 10.1063/1.4928078] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the pair complexation of a single, highly charged polyelectrolyte (PE) chain (of 25 or 50 monomers) with like-charged patchy protein models (CPPMs) by means of implicit-solvent, explicit-salt Langevin dynamics computer simulations. Our previously introduced set of CPPMs embraces well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size with mono- and multipole moments comparable to those of globular proteins with similar size. We observe large binding affinities between the CPPM and the like-charged PE in the tens of the thermal energy, kBT, that are favored by decreasing salt concentration and increasing charge of the patch(es). Our systematic analysis shows a clear correlation between the distance-resolved potentials of mean force, the number of ions released from the PE, and CPPM orientation effects. In particular, we find a novel two-site binding behavior for PEs in the case of two-patched CPPMs, where intermediate metastable complex structures are formed. In order to describe the salt-dependence of the binding affinity for mainly dipolar (one-patched) CPPMs, we introduce a combined counterion-release/Debye-Hückel model that quantitatively captures the essential physics of electrostatic complexation in our systems.
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Affiliation(s)
- Cemil Yigit
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
| | - Jan Heyda
- Department of Physical Chemistry, University of Chemistry and Technology, Prague, 166 28 Praha 6, Czech Republic
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
| | - Joachim Dzubiella
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
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29
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Hansen J, Platten F, Wagner D, Egelhaaf SU. Tuning protein-protein interactions using cosolvents: specific effects of ionic and non-ionic additives on protein phase behavior. Phys Chem Chem Phys 2016; 18:10270-80. [PMID: 27020538 DOI: 10.1039/c5cp07285a] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cosolvents are routinely used to modulate the (thermal) stability of proteins and, hence, their interactions with proteins have been studied intensely. However, less is known about their specific effects on protein-protein interactions, which we characterize in terms of the protein phase behavior. We analyze the phase behavior of lysozyme solutions in the presence of sodium chloride (NaCl), guanidine hydrochloride (GuHCl), glycerol, and dimethyl sulfoxide (DMSO). We experimentally determined the crystallization boundary (XB) and, in combination with data on the cloud-point temperatures (CPTs), the crystallization gap. In agreement with other studies, our data indicate that the additives might affect the protein phase behavior through electrostatic screening and additive-specific contributions. At high salt concentrations, where electrostatic interactions are screened, both the CPT and the XB are found to be linear functions of the additive concentration. Their slopes quantify the additive-specific changes of the phase behavior and thus of the protein-protein interactions. While the specific effect of NaCl is to induce attractions between proteins, DMSO, glycerol and GuHCl (with increasing strength) weaken attractions and/or induce repulsions. Except for DMSO, changes of the CPT are stronger than those of the XB. Furthermore, the crystallization gap widens in the case of GuHCl and glycerol and narrows in the case of NaCl. We relate these changes to colloidal interaction models, namely square-well and patchy interactions.
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Affiliation(s)
- Jan Hansen
- Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany.
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30
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Lund M. Anisotropic protein-protein interactions due to ion binding. Colloids Surf B Biointerfaces 2015; 137:17-21. [PMID: 26162300 DOI: 10.1016/j.colsurfb.2015.05.054] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/11/2015] [Accepted: 05/13/2015] [Indexed: 10/23/2022]
Abstract
Self-association of proteins is strongly affected by long-range electrostatic interactions caused by equilibrium adsorption of small ions such as protons and multivalent metals. By affecting the molecular net charge, solution pH is thus a widely used parameter to tune stability and phase behavior of proteins. We here review recent studies where the charge distribution is perturbed not only by protons, but also by other binding ions, leading to a rich and inherently anisotropic charge distribution. Focus is on coarse grained simulation techniques, coupled to experiments of protein-protein interaction at varying salt and pH conditions. Finally, and with future bio-colloidal models in mind, we discuss the validity of coarse graining charge anisotropy using electric multipoles.
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Affiliation(s)
- Mikael Lund
- Division of Theoretical Chemistry, Lund University, PO Box 124, SE-22100 Lund, Sweden.
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