1
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Zhou S. Effective electrostatic forces between two neutral surfaces with surface charge separation: valence asymmetry and dielectric constant heterogeneity. Mol Phys 2022. [DOI: 10.1080/00268976.2022.2094296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- S. Zhou
- School of Physics and Electronics, Central South University, Changsha, People’s Republic of China
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2
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Aguirre-Manzo LA, González-Mozuelos P. A self-consistent Ornstein-Zernike jellium for highly charged colloids (microgels) in suspensions with added salt. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:275101. [PMID: 34047280 DOI: 10.1088/1361-648x/abfe95] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
This work discusses a jellium scheme, built within the framework of the multicomponent Ornstein-Zernike (OZ) equation, which is capable of describing the collective structure of suspensions of highly charged colloids with added salt, even in the presence of finite-size multivalent microions. This approach uses a suitable approximation to decouple the microion-microion correlations from the macroion-microion profiles, which in combination with the methodology from the dressed ion theory (DIT) gives a full account of the electrostatic effective potential among the colloids. The main advantages of the present contribution reside in its ability to manage the short-range potentials and non-linear correlations among the microions, as well as its realistic characterization of the ionic clouds surrounding each macroion. The structure factors predicted by this jellium scheme are contrasted with previously reported experimental results for microgel suspensions with monovalent salts (2019Phys. Rev. E100032602), thus validating its high accuracy in these situations. The present theoretical analysis is then extended to microgel suspensions with multivalent salts, which reveals the prominent influence of the counterion valence on the makeup of the effective potentials. Although the induced differences may be difficult to identify through the mesoscopic structure, our results suggest that the microgel collapsing transition may be used to enhance these distinct effects, thus giving a feasible experimental probe for these phenomena.
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Affiliation(s)
- L A Aguirre-Manzo
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, Ciudad de México, C. P. 07360, Mexico
| | - P González-Mozuelos
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, Ciudad de México, C. P. 07360, Mexico
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3
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Aguirre-Manzo LA, González-Mozuelos P. Volume transition effects on the correlations and effective interactions among highly charged microgels. SOFT MATTER 2020; 16:5081-5093. [PMID: 32458939 DOI: 10.1039/d0sm00486c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recent experimental studies have demonstrated the huge influence that the volume phase transition (VPT) has on the collective structure of highly charged thermo-responsive microgels in aqueous solution with low concentrations of added monovalent salt, thus opening a promising new route for controlling the overall properties of practical colloidal suspensions. We present here an analysis of this structure based on the effective electrostatic potential obtained with the exact methodology of the dressed ion theory (DIT). Starting with a description at the primitive model level, we determine the correlations among the components of our model system (macroions plus monovalent anions and cations) by utilizing the two-density integral equation theory, thus allowing us to consider realistic values for the microgel charges. The resulting microgel structure factors show a good agreement with the reported light scattering measurements, whereas the microscopic pair distributions reveal that in this regime the shrunken states promote an enhanced counterion absorption into the microgels. This packing of counterions inside the microgels induces strongly non-linear correlations among the microions, and in turn provokes a substantial weakening of the microgel-microgel correlations. The ensuing effective interactions are then obtained by contracting the description to the level in which only the macroions are present. We find not only that the magnitude and reach of the corresponding pair potentials are markedly inhibited in the shrunken states, but also that their general form diverges from the conventional screened Coulomb shape. This makes it necessary to rethink the concepts of effective charge and screening length.
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Affiliation(s)
- L A Aguirre-Manzo
- Departamento de Física, Cinvestav del I. P. N., Av., Instituto Politécnico Nacional 2508, Ciudad de México, C. P. 07360, Mexico.
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4
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Silkina EF, Molotilin TY, Maduar SR, Vinogradova OI. Ionic equilibria and swelling of soft permeable particles in electrolyte solutions. SOFT MATTER 2020; 16:929-938. [PMID: 31815270 DOI: 10.1039/c9sm01602c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We discuss osmotic equilibria between soft permeable particles, of radius R and volume charge density ρ, and bulk electrolyte solutions of inverse Debye length κ. Existing models are based on a simplified assumption of weakly charged particles. Here we derive analytical approximations for the distribution of potentials, ions and pressure in a system, suitable even when ρ is quite large. Our theory is valid not only for "large" particles (κR≫ 1), where the central part is fully screened, but also for weakly screened "small" particles (κR≤ 1) with overlapping inner diffuse layers. Besides, we present novel coarse-grained simulations to validate the analysis and illustrate the variation of potential/ion profiles in response to changes in κR and ρ. Our simulations also allow us to argue that swelling of both "large" and "small" particles is uniform, although their inner non-uniform local pressure profiles are essentially and qualitatively different. These results are directly relevant for a variety of permeable charged objects, from polymer micro- and nanogels to more rigid porous colloids.
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Affiliation(s)
- Elena F Silkina
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Taras Y Molotilin
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Salim R Maduar
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Olga I Vinogradova
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia. and Department of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia and DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany
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5
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Moncho-Jordá A, Quesada-Pérez M. Crossover of the effective charge in ionic thermoresponsive hydrogel particles. Phys Rev E 2019; 100:050602. [PMID: 31869873 DOI: 10.1103/physreve.100.050602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Indexed: 06/10/2023]
Abstract
We use a generalized nonlinear Poisson-Boltzmann cell model that includes excluded-volume effects to investigate whether the effective charge (Z_{eff}) of charged thermosensitive hydrogel particles increases or decreases upon the hydrogel thermal collapse. We find the existence of a crossover charge, Z^{*}, that separates two regimes. For hydrogel bare charges below Z^{*} the system shows a behavior consistent with theories based on linear approximations, i.e., Z_{eff} increases in the collapsed state. However, for bare charges above Z^{*}, the system enters an anomalous regime, in which Z_{eff} decreases in the collapsed state. We show that diluted hydrogel suspensions at low ionic strength are more likely to follow the anomalous behavior. Our theory provides a full physical justification for the controversial theoretical and experimental results reported in this regard, and describes how the interplay between electrostatic, excluded-volume and entropic effects affects this crossover.
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Affiliation(s)
- A Moncho-Jordá
- Departamento de Física Aplicada, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
- Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - M Quesada-Pérez
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
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6
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Aguirre-Manzo LA, Ledesma-Motolinía M, Rojas-Ochoa LF, Trappe V, Callejas-Fernández J, Haro-Pérez C, González-Mozuelos P. Accounting for effective interactions among charged microgels. Phys Rev E 2019; 100:032602. [PMID: 31640009 DOI: 10.1103/physreve.100.032602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Indexed: 06/10/2023]
Abstract
We introduce a theoretical approach to describe structural correlations among charged permeable spheres at finite particle concentrations. This theory explicitly accounts for correlations among microions and between microions and macroions and allows for the proposal of an effective interaction among macroions that successfully captures structural correlations observed in poly-N-isopropyl acrylamide microgel systems. In our description the bare charge is fixed and independent of the microgel size, the microgel concentration, and the ionic strength, which contrasts with results obtained using linear response approximations, where the bare charge needs to be adapted to properly account for microgel correlations obtained at different conditions.
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Affiliation(s)
- L A Aguirre-Manzo
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico
| | - M Ledesma-Motolinía
- Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana-Azcapotzalco, 02200 Ciudad de México, Mexico
| | - L F Rojas-Ochoa
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico
| | - V Trappe
- Departement de Physique, Université de Fribourg, 1700 Fribourg, Switzerland
| | | | - C Haro-Pérez
- Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana-Azcapotzalco, 02200 Ciudad de México, Mexico
| | - P González-Mozuelos
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico
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7
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Mkanya A, Pellicane G, Ramos FS, Ramos AM, Lee LL. On the structure, property, and phase behaviour of the symmetric Yukawa mixtures: testing of the consistent integral equation theories. Mol Phys 2019. [DOI: 10.1080/00268976.2018.1542165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Anele Mkanya
- School of Chemistry and Physics, University of Kwazulu-Natal, Pietermaritzburg, South Africa
- National Institute for Theoretical Physics (NITheP), KZN node, Pietermaritzburg, South Africa
| | - Giuseppe Pellicane
- School of Chemistry and Physics, University of Kwazulu-Natal, Pietermaritzburg, South Africa
- National Institute for Theoretical Physics (NITheP), KZN node, Pietermaritzburg, South Africa
| | - Franklin S. Ramos
- Department of Chemical and Materials Engineering, California State University, Pomona, CA, USA
| | - Ana M. Ramos
- Department of Chemical and Materials Engineering, California State University, Pomona, CA, USA
| | - Lloyd L. Lee
- School of Chemistry and Physics, University of Kwazulu-Natal, Pietermaritzburg, South Africa
- Department of Chemical and Materials Engineering, California State University, Pomona, CA, USA
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8
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Chudoba R, Heyda J, Dzubiella J. Tuning the collapse transition of weakly charged polymers by ion-specific screening and adsorption. SOFT MATTER 2018; 14:9631-9642. [PMID: 30457144 DOI: 10.1039/c8sm01646a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The experimentally observed swelling and collapse response of weakly charged polymers to the addition of specific salts displays quite convoluted behavior that is not easy to categorize. Here we use a minimalistic implicit-solvent/explicit-salt simulation model with a focus on ion-specific interactions between ions and a single weakly charged polyelectrolyte to qualitatively explain the observed effects. In particular, we demonstrate ion-specific screening and bridging effects cause collapse at low salt concentrations whereas the same strong ion-specific direct interactions drive re-entrant swelling at high concentrations. Consistently with experiments, a distinct salt concentration at which the salting-out power of anions inverts from the reverse to direct Hofmeister series is observed. At this so called isospheric point, the ion-specific effects vanish. Furthermore, with additional simplifying assumptions, an ion-specific mean-field model is developed for the collapse transition which quantitatively agrees with the simulations. Our work demonstrates the sensitivity of the structural behavior of charged polymers to the addition of specific salt beyond simple screening and shall be useful for further guidance of experiments.
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Affiliation(s)
- Richard Chudoba
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, D-12489 Berlin, Germany.
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9
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Micali N, Bertoldo M, Buratti E, Nigro V, Angelini R, Villari V. Interpenetrating Polymer Network Microgels in Water: Effect of Composition on the Structural Properties and Electrosteric Interactions. Chemphyschem 2018; 19:2894-2901. [PMID: 30074305 DOI: 10.1002/cphc.201800707] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/11/2022]
Abstract
Microgels of cross-linked interpenetrating polymer networks (IPNs) are very versatile systems combining the properties of colloids and polymers. Herein we study IPN microgels composed of poly(N-isopropylacrylamide) and poly(acrylic acid) to understand how weight composition and reactant concentrations affect their structural, conformational and electrosteric properties in water. The results show that it is possible to drive the formation of microgels with the desired properties by adjusting IPN composition and preparation method during the synthesis. During synthesis, the polymerization of acrylic acid triggers the merging among IPNs via covalent linking, giving rise to microgels with larger mass and size, the effect being larger for higher concentration of the reactants. In addition, a close relation between the microgel internal conformation and the colloidal stability is observed, due to the presence of screened groups inside the microgel.
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Affiliation(s)
- Norberto Micali
- CNR-IPCF Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, Viale F. Stagno d'Alcontres 37, I-98158, Messina, Italy
| | - Monica Bertoldo
- CNR-IPCF Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, Area della Ricerca, Via G. Moruzzi 1, I-56124, Pisa, Italy
| | - Elena Buratti
- CNR-IPCF Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, Area della Ricerca, Via G. Moruzzi 1, I-56124, Pisa, Italy
| | - Valentina Nigro
- CNR-ISC Istituto dei Sistemi Complessi, sede Sapienza, Consiglio Nazionale delle Ricerche, P.le Aldo Moro 5, I-00185, Roma, Italy.,Dipartimento di Fisica, Sapienza Università di Roma, P.le Aldo Moro 5, 00185, Roma, Italy
| | - Roberta Angelini
- CNR-ISC Istituto dei Sistemi Complessi, sede Sapienza, Consiglio Nazionale delle Ricerche, P.le Aldo Moro 5, I-00185, Roma, Italy.,Dipartimento di Fisica, Sapienza Università di Roma, P.le Aldo Moro 5, 00185, Roma, Italy
| | - Valentina Villari
- CNR-IPCF Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, Viale F. Stagno d'Alcontres 37, I-98158, Messina, Italy
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10
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Adroher-Benítez I, Moncho-Jordá A, Odriozola G. Conformation change of an isotactic poly (N-isopropylacrylamide) membrane: Molecular dynamics. J Chem Phys 2018; 146:194905. [PMID: 28527458 DOI: 10.1063/1.4983525] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, isotactic Poly (N-Isopropylacrylamide)-PNIPAM-in neat water and in electrolyte solutions is studied by means of molecular dynamics simulations. This is done for an infinitely diluted oligomer and for an assembly of several PNIPAM chains arranged into a planar membrane configuration with a core-shell morphology. We employed two different force fields, AMBER (assisted model building with energy refinement) and OPLS-AA (all atom - optimized potentials for liquid simulations) in combination with extended simple point charge water. Despite the more water insoluble character of isotactic oligomers, our results support the existence of a coil to globule transition for the isolated 30-mer. This may imply the existence of an oligomer rich phase of coil-like structures in equilibrium with a water rich phase for temperatures close but below the coil to globule transition temperature, TΘ. However, the obtained coil structure is much more compact than that corresponding to the syndiotactic chain. Our estimations of TΘ are (308±5) K and (303±5) K for AMBER and OPLS-AA, respectively. The membrane configuration allows one to include chain-chain interactions, to follow density profiles of water, polymer, and solutes, and accessing the membrane-water interface tension. Results show gradual shrinking and swelling of the membrane by switching temperature above and below TΘ, as well as the increase and decrease of the membrane-water interface tension. Finally, concentration profiles for 1M NaCl and 1M NaI electrolytes are shown, depicting a strong salting-out effect for NaCl and a much lighter effect for NaI, in good qualitative agreement with experiments.
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Affiliation(s)
- Irene Adroher-Benítez
- Departamento de Física Aplicada e Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Arturo Moncho-Jordá
- Departamento de Física Aplicada e Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Gerardo Odriozola
- Área de Física de Procesos Irreversibles, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana, Ave. San Pablo 180 Col., Reynosa-Tamaulipas, 02200 Ciudad de México, Mexico
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11
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Weyer TJ, Denton AR. Concentration-dependent swelling and structure of ionic microgels: simulation and theory of a coarse-grained model. SOFT MATTER 2018; 14:4530-4540. [PMID: 29796467 DOI: 10.1039/c8sm00799c] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We study swelling and structural properties of ionic microgel suspensions within a comprehensive coarse-grained model that combines the polymeric and colloidal natures of microgels as permeable, compressible, charged spheres governed by effective interparticle interactions. The model synthesizes the Flory-Rehner theory of cross-linked polymer gels, the Hertz continuum theory of effective elastic interactions, and a theory of density-dependent effective electrostatic interactions. Implementing the model using Monte Carlo simulation and thermodynamic perturbation theory, we compute equilibrium particle size distributions, swelling ratios, volume fractions, net valences, radial distribution functions, and static structure factors as functions of concentration. Trial Monte Carlo moves comprising particle displacements and size variations are accepted or rejected based on the total change in elastic and electrostatic energies. The theory combines first-order thermodynamic perturbation and variational free energy approximations. For illustrative system parameters, theory and simulation agree closely at concentrations ranging from dilute to beyond particle overlap. With increasing concentration, as microgels deswell, we predict a decrease in the net valence and an unusual saturation of pair correlations. Comparison with experimental data for deionized, aqueous suspensions of PNIPAM particles demonstrates the capacity of the coarse-grained model to predict and interpret measured swelling behavior.
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Affiliation(s)
- Tyler J Weyer
- Department of Physics, North Dakota State University, Fargo, ND 58108-6050, USA.
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12
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Quesada-Pérez M, Maroto-Centeno JA, Martín-Molina A, Moncho-Jordá A. Direct determination of forces between charged nanogels through coarse-grained simulations. Phys Rev E 2018; 97:042608. [PMID: 29758622 DOI: 10.1103/physreve.97.042608] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Indexed: 06/08/2023]
Abstract
In this work, electrostatic forces between charged nanogels are explored through coarse-grained simulations. These simulations allow us to explicitly consider the complex topology of these nanoparticles and provide reliable force values to examine highly charged nanogels of a few tens of nanometers. The results obtained here clearly reveal that the electrostatic interactions between these nanoparticles are not governed by the net charge of the nanogel, which includes not only the charge of the polymer network but also the charge of ions inside. Thus two theoretical procedures for predicting effective charges are also proposed and investigated. Both provide predictions of the same order and capture the behavior found for the effective charge obtained from simulations.
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Affiliation(s)
- Manuel Quesada-Pérez
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700, Linares, Jaén, Spain
| | - José Alberto Maroto-Centeno
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700, Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
- Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Arturo Moncho-Jordá
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
- Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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13
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Pérez-Mas L, Martín-Molina A, Quesada-Pérez M, Moncho-Jordá A. Maximizing the absorption of small cosolutes inside neutral hydrogels: steric exclusion versus hydrophobic adhesion. Phys Chem Chem Phys 2018; 20:2814-2825. [PMID: 29323684 DOI: 10.1039/c7cp07679g] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In this work the equilibrium absorption of nanometric cosolutes (which could represent drugs, reactants, small globular proteins and other kind of biomacromolecules) inside neutral hydrogels is studied. We specially focus on exploring, for different swelling states, the competition between the steric exclusion induced by the cross-linked polymer network constituting the hydrogel, and the solvent-induced short-range hydrophobic attraction between the polymer chains and the cosolute particle. For this purpose, the cosolute partition coefficient is calculated by means of coarse-grained grand canonical Monte Carlo simulations, and the results are compared to theoretical predictions based on the calculation of the excluded and binding volume around the polymer chains. For small hydrophobic attractions or large cosolute sizes, the steric repulsion dominates, and the partition coefficient decreases monotonically with the polymer volume fraction, ϕm. However, for large enough hydrophobic attraction strength, the interplay between hydrophobic adhesion and the steric exclusion leads to a maximum in the partition coefficient at certain intermediate polymer density. Good qualitative and quantitative agreement is achieved between simulation results and theoretical predictions in the limit of small ϕm, pointing out the importance of geometrical aspects of the cross-linked polymer network, even for hydrogels in the swollen state. In addition, the theory is able to predict analytically the onset of the maximum formation in terms of the details of the cosolute-monomer pair interaction, in good agreement with simulations too. Finally, the effect of the many-body attractions between the cosolute and multiple polymer chains is quantified. The results clearly show that these many-body attractions play a very relevant role determining the cosolute binding, enhancing its absorption in more than one order of magnitude.
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Affiliation(s)
- Luis Pérez-Mas
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Avenida Fuentenueva S/N, 18001 Granada, Spain
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14
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Kim WK, Moncho-Jordá A, Roa R, Kanduč M, Dzubiella J. Cosolute Partitioning in Polymer Networks: Effects of Flexibility and Volume Transitions. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01206] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Won Kyu Kim
- Institut
für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Arturo Moncho-Jordá
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Avenida Fuente Nueva, 18071 Granada, Spain
- Instituto
Carlos I de Física Teórica y Computacional, Facultad
de Ciencias, Universidad de Granada, Avenida Fuente Nueva S/N, 18071 Granada, Spain
| | - Rafael Roa
- Institut
für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Matej Kanduč
- Institut
für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Joachim Dzubiella
- Institut
für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Institut
für Physik, Humboldt-Universität zu Berlin, Newtonstr.
15, 12489 Berlin, Germany
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15
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Abstract
The accurate characterization of the electrical double layer properties of nanoparticles is of fundamental importance for optimizing their physicochemical properties for specific biotechnological and biomedical applications. In this article, we use classical solvation density functional theory and a surface complexation model to investigate the effects of the pH and the nanoparticle size on the structural and electrostatic properties of an electrolyte solution surrounding a spherical silica oxide nanoparticle. The formulation has been particularly useful for identifying dominant interactions governing the ionic driving force at a variety of pH levels and nanoparticle sizes. As a result of the energetic interplay displayed between electrostatic potential, ion-ion correlation and particle crowding effects on the nanoparticle surface titration, rich, non-trivial ion density profiles and mean electrostatic potential behavior have been found.
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Affiliation(s)
- Christian Hunley
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX 78249-5003, USA.
| | - Marcelo Marucho
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX 78249-5003, USA.
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16
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Adroher-Benítez I, Martín-Molina A, Ahualli S, Quesada-Pérez M, Odriozola G, Moncho-Jordá A. Competition between excluded-volume and electrostatic interactions for nanogel swelling: effects of the counterion valence and nanogel charge. Phys Chem Chem Phys 2017; 19:6838-6848. [DOI: 10.1039/c6cp08683g] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The equilibrium distribution of monovalent and trivalent ions within a thermo-responsive charged nanogel is investigated using Monte Carlo simulations and Ornstein–Zernike equations.
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Affiliation(s)
- Irene Adroher-Benítez
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
| | - Alberto Martín-Molina
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
| | - Silvia Ahualli
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
| | - Manuel Quesada-Pérez
- Departamento de Física
- Escuela Politécnica Superior de Linares
- Universidad de Jaeén
- 23700 Linares
- Spain
| | - Gerardo Odriozola
- Área de Física de Procesos Irreversibles
- División de Ciencias Básicas e Ingeniería
- Universidad Autónoma Metropolitana
- 02200 México CD de México
- Mexico
| | - Arturo Moncho-Jordá
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
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17
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Urich M, Denton AR. Swelling, structure, and phase stability of compressible microgels. SOFT MATTER 2016; 12:9086-9094. [PMID: 27774556 DOI: 10.1039/c6sm02056a] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Microgels are soft colloidal particles that, when dispersed in a solvent, swell and deswell in response to changes in environmental conditions, such as temperature, concentration, and pH. Using Monte Carlo simulation, we model bulk suspensions of microgels that interact via Hertzian elastic interparticle forces and can expand or contract via trial moves that allow particles to change size in accordance with the Flory-Rehner free energy of cross-linked polymer gels. We monitor the influence of particle compressibility, size fluctuations, and concentration on bulk structural and thermal properties by computing particle swelling ratios, radial distribution functions, static structure factors, osmotic pressures, and freezing densities. For microgels in the nanoscale size range, particle compressibility and associated size fluctuations suppress crystallization, shifting the freezing transition to a higher density than for the hard-sphere fluid. As densities increase beyond close packing, microgels progressively deswell, while their intrinsic size distribution grows increasingly polydisperse.
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Affiliation(s)
- Matthew Urich
- Department of Physics, North Dakota State University, Fargo, ND 58108-6050, USA.
| | - Alan R Denton
- Department of Physics, North Dakota State University, Fargo, ND 58108-6050, USA.
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18
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Braibanti M, Haro-Pérez C, Quesada-Pérez M, Rojas-Ochoa LF, Trappe V. Impact of volume transition on the net charge of poly-N-isopropyl acrylamide microgels. Phys Rev E 2016; 94:032601. [PMID: 27739781 DOI: 10.1103/physreve.94.032601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Indexed: 06/06/2023]
Abstract
We explore the electrostatic properties of poly-N-isopropyl acrylamide microgels in dilute, quasi-de-ionized dispersions and show that the apparent net charge of these thermosensitive microgels is an increasing function of their size, the size being conveniently varied by temperature. Our experimental results obtained in a combination of light scattering, conductivity, and mobility experiments are consistent with those obtained in Poisson-Boltzmann cell model calculations, effectively indicating that upon shrinking the number of counterions entrapped within the microgels increases. Remarkably, this behavior shows that the electrostatic energy per particle remains constant upon swelling or deswelling the microgel, resulting in a square root dependence of the net charge on the particle radius.
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Affiliation(s)
- M Braibanti
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - C Haro-Pérez
- Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana-Azcapotzalco, Avenida San Pablo 180, 02200 Ciudad de México, Mexico
| | - M Quesada-Pérez
- Departamento de Física, Universidad de Jaén, Escuela Politécnica Superior de Linares, 23700 Linares, Spain
| | - L F Rojas-Ochoa
- Departamento de Física, CINVESTAV-IPN, Avenida Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico
| | - V Trappe
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
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19
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Adroher-Benítez I, Ahualli S, Bastos-González D, Ramos J, Forcada J, Moncho-Jordá A. The effect of electrosteric interactions on the effective charge of thermoresponsive ionic microgels: Theory and experiments. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Irene Adroher-Benítez
- Departamento de Física Aplicada, Facultad de Ciencias; Universidad de Granada; Campus Fuentenueva S/N Granada 18071 Spain
| | - Silvia Ahualli
- Departamento de Física Aplicada, Facultad de Ciencias; Universidad de Granada; Campus Fuentenueva S/N Granada 18071 Spain
| | - Delfi Bastos-González
- Departamento de Física Aplicada, Facultad de Ciencias; Universidad de Granada; Campus Fuentenueva S/N Granada 18071 Spain
| | - José Ramos
- Grupo de Ingeniería Química, Facultad de Ciencias Químicas; Universidad del País Vasco/EHU; San Sebastián 20080 Spain
| | - Jacqueline Forcada
- Grupo de Ingeniería Química, Facultad de Ciencias Químicas; Universidad del País Vasco/EHU; San Sebastián 20080 Spain
| | - Arturo Moncho-Jordá
- Departamento de Física Aplicada and Instituto Carlos I de Física Teórica y Computacional; Universidad de Granada; Campus Fuentenueva S/N Granada 18071 Spain
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20
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González-Mozuelos P. Effective electrostatic interactions among charged thermo-responsive microgels immersed in a simple electrolyte. J Chem Phys 2016; 144:054902. [DOI: 10.1063/1.4941324] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- P. González-Mozuelos
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, Mexico, Distrito Federal, C. P. 07360, Mexico
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21
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Moncho-Jordá A, Dzubiella J. Swelling of ionic microgel particles in the presence of excluded-volume interactions: a density functional approach. Phys Chem Chem Phys 2016; 18:5372-85. [DOI: 10.1039/c5cp07794j] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In this work a new density functional theory framework is developed to predict the salt-concentration dependent swelling state of charged microgels and the local concentration of monovalent ions inside and outside the microgel.
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Affiliation(s)
- Arturo Moncho-Jordá
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18071 Granada
- Spain
| | - Joachim Dzubiella
- Institut für Weiche Materie und Funktionale Materialien
- Helmholtz-Zentrum Berlin
- 14109 Berlin
- Germany
- Institut für Physik, Humboldt-Universität zu Berlin
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22
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Ledesma-Motolinía M, Braibanti M, Rojas-Ochoa LF, Haro-Pérez C. Interplay between internal structure and optical properties of thermosensitive nanogels. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.07.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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23
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Quesada-Pérez M, Ahualli S, Martín-Molina A. Temperature-sensitive nanogels in the presence of salt: explicit coarse-grained simulations. J Chem Phys 2015; 141:124903. [PMID: 25273470 DOI: 10.1063/1.4895960] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In this work, coarse-grained simulations of two charged thermo-shrinking nanogels (with degrees of ionization of 0.125 and 0.250) in the presence of 1:1 and 3:1 electrolytes have been explicitly performed through the bead-spring model of polyelectrolyte. In a first set of simulations, salt concentrations for 1:1 and 3:1 electrolytes ranged from 1 to 100 mM and from 0.167 to 16.7 mM, respectively, whereas temperature remained fixed at a value for which hydrophobic forces were negligible in our case (288 K). The sizes of swollen nanogels are smaller when trivalent cations are present, but they do not change significantly in the range of concentrations of 3:1 electrolyte studied here. It should be also stressed that trivalent cations neutralize the nanogel charge more efficiently. According to these results the electrostatic repulsion plays an important role. In a second set of simulations, the temperature varied from 288 to 333 K to study the effect of salt on the thermal response when hydrophobic forces are not negligible. For the nanogels with the lowest degree of ionization, the behavior of the radius with increasing the temperature can be described by a sigmoid function, which shifts towards lower temperatures in the presence of salt. This shift is more clearly observed for trivalent cations, even at low concentrations. For the nanogels with the highest degree of ionization, the effect of additional electrolyte is also noticeable. In this case, hydrophobic forces are not the only responsible for their shrinkage in the presence of trivalent cations. The surface electrostatic potential and the concentration of salt cations inside the nanogel have been computed from simulations and a modified Poisson-Boltzmann (PB) cell model. The thermosensitivity in size have certain influence on the sensitivity of these properties to temperature changes. The rich behavior of the surface electrostatic potential and the uptake of salt cations are successfully predicted by the modified PB cell model proposed (at least qualitatively). Particularly, the model is able to predict how the retention of salt cations depends on their charge and the ionic valence when nanogels shrink.
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Affiliation(s)
- Manuel Quesada-Pérez
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Silvia Ahualli
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Grupo de Física de Fluidos y Biocoloides, Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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24
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Adroher-Benítez I, Ahualli S, Martín-Molina A, Quesada-Pérez M, Moncho-Jordá A. Role of Steric Interactions on the Ionic Permeation Inside Charged Microgels: Theory and Simulations. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00356] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Irene Adroher-Benítez
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Silvia Ahualli
- Departamento
de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Manuel Quesada-Pérez
- Departamento
de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Arturo Moncho-Jordá
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
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25
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Barrios-Contreras EA, González-Tovar E, Guerrero-García GI. The dominance of small ions in the electric double layer of size- and charge-asymmetric electrolytes: a mean-field study on the charge reversal and surface charge amplification. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1018853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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26
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Colla T, Likos CN, Levin Y. Equilibrium properties of charged microgels: A Poisson-Boltzmann-Flory approach. J Chem Phys 2014; 141:234902. [DOI: 10.1063/1.4903746] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Ovanesyan Z, Medasani B, Fenley MO, Guerrero-García GI, de la Cruz MO, Marucho M. Excluded volume and ion-ion correlation effects on the ionic atmosphere around B-DNA: theory, simulations, and experiments. J Chem Phys 2014; 141:225103. [PMID: 25494770 PMCID: PMC4265039 DOI: 10.1063/1.4902407] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 11/12/2014] [Indexed: 12/19/2022] Open
Abstract
The ionic atmosphere around a nucleic acid regulates its stability in aqueous salt solutions. One major source of complexity in biological activities involving nucleic acids arises from the strong influence of the surrounding ions and water molecules on their structural and thermodynamic properties. Here, we implement a classical density functional theory for cylindrical polyelectrolytes embedded in aqueous electrolytes containing explicit (neutral hard sphere) water molecules at experimental solvent concentrations. Our approach allows us to include ion correlations as well as solvent and ion excluded volume effects for studying the structural and thermodynamic properties of highly charged cylindrical polyelectrolytes. Several models of size and charge asymmetric mixtures of aqueous electrolytes at physiological concentrations are studied. Our results are in good agreement with Monte Carlo simulations. Our numerical calculations display significant differences in the ion density profiles for the different aqueous electrolyte models studied. However, similar results regarding the excess number of ions adsorbed to the B-DNA molecule are predicted by our theoretical approach for different aqueous electrolyte models. These findings suggest that ion counting experimental data should not be used alone to validate the performance of aqueous DNA-electrolyte models.
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Affiliation(s)
- Zaven Ovanesyan
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
| | - Bharat Medasani
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
| | - Marcia O Fenley
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA
| | - Guillermo Iván Guerrero-García
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí, Mexico
| | - Mónica Olvera de la Cruz
- Department of Chemistry and Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Marcelo Marucho
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
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28
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Hanel C, Likos CN, Blaak R. Effective Interactions between Multilayered Ionic Microgels. MATERIALS 2014; 7:7689-7705. [PMID: 28788269 PMCID: PMC5456439 DOI: 10.3390/ma7127689] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 11/17/2014] [Accepted: 11/27/2014] [Indexed: 11/23/2022]
Abstract
Using a one-component reduction formalism, we calculate the effective interactions and the counterion density profiles for microgels that feature a multilayered shell structure. We follow a strategy that involves second order perturbation theory and obtain analytical expressions for the effective interactions by modeling the layers of the particles as linear superpostion of homogeneously charged spheres. The general method is applied to the important case of core–shell microgels and compared with the well-known results for a microgel that can be approximated by a macroscopic, and homogeneously charged, spherical macroion.
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Affiliation(s)
- Clemens Hanel
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria.
| | - Christos N Likos
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria.
| | - Ronald Blaak
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria.
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29
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Quesada-Pérez M, Ahualli S, Martín-Molina A. Thermo-responsive gels in the presence of monovalent salt at physiological concentrations: A Monte Carlo simulation study. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/polb.23576] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Manuel Quesada-Pérez
- Departamento de Física; Escuela Politécnica Superior de Linares, Universidad de Jaén; 23700 Linares Jaén Spain
| | - Silvia Ahualli
- Departamento de Física; Escuela Politécnica Superior de Linares, Universidad de Jaén; 23700 Linares Jaén Spain
| | - Alberto Martín-Molina
- Grupo de Física de Fluidos y Biocoloides; Departamento de Física Aplicada; Facultad de Ciencias, Universidad de Granada; 18071 Granada Spain
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30
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Moncho-Jordá A, Adroher-Benítez I. Ion permeation inside microgel particles induced by specific interactions: from charge inversion to overcharging. SOFT MATTER 2014; 10:5810-5823. [PMID: 24974885 DOI: 10.1039/c4sm00243a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this work we have performed a theoretical study of a system formed by ionic microgels in the presence of monovalent salt with the help of Ornstein-Zernike integral equations within the hypernetted-chain (HNC) approximation. We focus in particular on analysing the role that the short-range specific interactions between the polymer fibres of the microgel and the incoming ions have on the equilibrium ion distribution inside and outside the microgel. For this purpose, a theoretical model based on the equilibrium partitioning effect is developed to determine the interaction between the microgel particle and a single ion. The results indicate that when counterions are specifically attracted to the polymer fibres of the microgel, an enhanced counterion accumulation occurs that induces the charge inversion of the microgel and a strong increase of the microgel net charge (or overcharging). In the case of coions, the specific attraction is also able to provoke the coion adsorption even though they are electrostatically repelled, and so increasing the microgel charge (true overcharging). Moreover, we show that ion adsorption onto the microgel particle is very different in swollen and shrunken states due to the competition between specific attraction and steric repulsion. In particular, ion adsorption occurs preferentially in the internal core of the particle for swollen states, whereas it is mainly concentrated in the external shell for de-swollen configurations. Finally, we observe the existence of a critical salt concentration, where the net charge of the microgels vanishes; above this inversion point the net charge of the microgels increases again, thus leading to reentrant stability of microgel suspensions.
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Affiliation(s)
- A Moncho-Jordá
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain.
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31
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Xu W, Chen W, Chen H. Modeling of soft interfacial volume fraction in composite materials with complex convex particles. J Chem Phys 2014; 140:034704. [PMID: 25669404 DOI: 10.1063/1.4861664] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Wenxiang Xu
- Institute of Soft Matter Mechanics, College of Mechanics and Materials, Hohai University, Nanjing 210098, China
| | - Wen Chen
- Institute of Soft Matter Mechanics, College of Mechanics and Materials, Hohai University, Nanjing 210098, China
| | - Huisu Chen
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
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32
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Ahualli S, Martín-Molina A, Quesada-Pérez M. Excluded volume effects on ionic partitioning in gels and microgels: a simulation study. Phys Chem Chem Phys 2014; 16:25483-91. [DOI: 10.1039/c4cp03314k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An analytical expression accounting for excluded volume effects on ionic partitioning in gels is tested through Monte Carlo simulations.
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Affiliation(s)
- Silvia Ahualli
- Departamento de Física
- Escuela Politécnica Superior de Linares
- Universidad de Jaén
- Linares, Spain
| | - Alberto Martín-Molina
- Grupo de Física de Fluidos y Biocoloides
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18071 Granada, Spain
| | - Manuel Quesada-Pérez
- Departamento de Física
- Escuela Politécnica Superior de Linares
- Universidad de Jaén
- Linares, Spain
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33
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Guerrero-García GI, González-Mozuelos P, Olvera de la Cruz M. Large counterions boost the solubility and renormalized charge of suspended nanoparticles. ACS NANO 2013; 7:9714-9723. [PMID: 24180597 DOI: 10.1021/nn404477b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Colloidal particles are ubiquitous in biology and in everyday products such as milk, cosmetics, lubricants, paints, or drugs. The stability and aggregation of colloidal suspensions are of paramount importance in nature and in diverse nanotechnological applications, including the fabrication of photonic materials and scaffolds for biological assemblies, gene therapy, diagnostics, targeted drug delivery, and molecular labeling. Electrolyte solutions have been extensively used to stabilize and direct the assembly of colloidal particles. In electrolytes, the effective electrostatic interactions among the suspended colloids can be changed over various length scales by tuning the ionic concentration. However, a major limitation is gelation or flocculation at high salt concentrations. This is explained by classical theories, which show that the electrostatic repulsion among charged colloids is significantly reduced at high electrolyte concentrations. As a result, these screened colloidal particles are expected to aggregate due to short-range attractive interactions or dispersion forces as the salt concentration increases. We discuss here a robust, tunable mechanism for colloidal stability by which large counterions prevent highly charged nanoparticles from aggregating in salt solutions with concentrations up to 1 M. Large counterions are shown to generate a thicker ionic cloud in the proximity of each charged colloid, which strengthens short-range repulsions among colloidal particles and also increases the corresponding renormalized colloidal charge perceived at larger separation distances. These effects thus provide a reliable stabilization mechanism in a broad range of biological and synthetic colloidal suspensions.
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34
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Moncho-Jordá A. Effective charge of ionic microgel particles in the swollen and collapsed states: The role of the steric microgel-ion repulsion. J Chem Phys 2013; 139:064906. [DOI: 10.1063/1.4817852] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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