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Lin YJ, Keh HJ. Sedimentation of a Charged Soft Sphere within a Charged Spherical Cavity. Molecules 2024; 29:3087. [PMID: 38999039 PMCID: PMC11242989 DOI: 10.3390/molecules29133087] [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: 06/05/2024] [Revised: 06/25/2024] [Accepted: 06/26/2024] [Indexed: 07/14/2024] Open
Abstract
The sedimentation of a soft particle composed of an uncharged hard sphere core and a charged porous surface layer inside a concentric charged spherical cavity full of a symmetric electrolyte solution is analyzed in a quasi-steady state. By using a regular perturbation method with small fixed charge densities of the soft sphere and cavity wall, a set of linearized electrokinetic equations relevant to the fluid velocity field, electrical potential profile, and ionic electrochemical potential energy distributions are solved. A closed-form formula for the sedimentation velocity of the soft sphere is obtained as a function of the ratios of core-to-particle radii, particle-to-cavity radii, particle radius-to-Debye screening length, and particle radius-to-porous layer permeation length. The existence of the surface charge on the cavity wall increases the settling velocity of the charged soft sphere, principally because of the electroosmotic enhancement of fluid recirculation within the cavity induced by the sedimentation potential gradient. When the porous layer space charge and cavity wall surface charge have the same sign, the particle velocity is generally enhanced by the presence of the cavity. When these fixed charges have opposite signs, the particle velocity will be enhanced/reduced by the presence of the cavity if the wall surface charge density is sufficiently large/small relative to the porous layer space charge density in magnitude. The effect of the wall surface charge on the sedimentation of the soft sphere increases with decreases in the ratios of core-to-particle radii, particle-to-cavity radii, and particle radius-to-porous layer permeation length but is not a monotonic function of the ratio of particle radius-to-Debye length.
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Affiliation(s)
- Yong-Jie Lin
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Huan J Keh
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
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2
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Ahualli S, Orozco-Barrera S, Medina Castillo A, Delgado A. Effect of coating nanostructure on the electrokinetics of polyelectrolyte-coated particles. Grafted vs adsorbed polymer. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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3
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Delgado AV, Ahualli S, Arroyo FJ, Jiménez ML, Carrique F. Electrokinetic detection of the salt-free condition in colloids. Application to polystyrene latexes. Adv Colloid Interface Sci 2022; 299:102539. [PMID: 34610864 DOI: 10.1016/j.cis.2021.102539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/28/2021] [Accepted: 09/28/2021] [Indexed: 01/06/2023]
Abstract
Because of their singular phenomenology, the so-called salt-free colloids constitute a special family of dispersed systems. Their main characteristic is that the dispersion medium ideally contains only the solvent and the ions compensating exactly the surface charge of the particles. These ions (often called released counterions) come into the solution when the surface groups responsible for the particles charge get ionized. An increasing effort is nowadays dedicated to rigorously compare theoretical model predictions for ideal salt-free suspensions, where only the released counterions are supposed to be present in solution, with appropriately devised experiments dealing with colloids as close as possible to the ideal salt-free ones. Of course, if the supporting solution is aqueous, the presence of atmospheric contamination and any other charged species different from the released counterions in the solution must be avoided. Because this is not an easy task, the presence of dissolved atmospheric CO2 and of H+ and OH- from water dissociation cannot be fully discarded in aqueous salt-free solutions (often denominated realistic in such case). Ultimately, at some point, the role of the released counterions will be comparable or even larger in highly charged concentrated colloids than that of added salts. These topics are covered in the present contribution. The model results are compared with experimental data on the dynamic mobility and dielectric dispersion of polystyrene spheres of various charges and sizes. As a rule, it is found that the model correctly predicts the significance of alpha and Maxwell-Wagner-O'Konski relaxations. Positions and amplitudes of such relaxations are well predicted, although it is necessary to assume that the released counterions are potassium or sodium instead of protons, otherwise the frequency spectra of experimental mobility and permittivity differ very significantly from those theoretically calculated. The proposed electrokinetic evaluation is an ideal tool for detecting in situ the possible contamination (or incomplete ion exchange of the latexes). A satisfactory agreement is found when potassium counterions are assumed to be in solution, mostly if one considers that the comparison is carried out without using any adjustable parameters.
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Affiliation(s)
- A V Delgado
- Departamento de Física Aplicada, Facultad de Ciencias, and MNat Unit of Excellence, Universidad de Granada, 18071 Granada, Spain.
| | - S Ahualli
- Departamento de Física Aplicada, Facultad de Ciencias, and MNat Unit of Excellence, Universidad de Granada, 18071 Granada, Spain
| | - F J Arroyo
- Departamento de Física, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071 Jaén, Spain
| | - M L Jiménez
- Departamento de Física Aplicada, Facultad de Ciencias, and MNat Unit of Excellence, Universidad de Granada, 18071 Granada, Spain
| | - F Carrique
- Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
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Maurya SK, Gopmandal PP, De S, Ohshima H, Sarkar S. Electrokinetics of Concentrated Suspension of Soft Particles with pH-Regulated Volumetric Charges. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:703-712. [PMID: 33412002 DOI: 10.1021/acs.langmuir.0c02805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This article presents a theoretical study on the electrokinetics of concentrated suspension of charge-regulated soft particles under a weak electric field and low potential assumptions. The inner core of the undertaken particle is "semisoft" in nature, which allows ion penetration while the fluid cannot flow within it, and the outer soft polymeric shell allows the flow of the ionized fluid. In addition, the inner core and the outer polyelectrolyte layer (PEL) bear pH-regulated basic and acidic functional groups, respectively. The Poisson-Boltzmann equation-based mathematical model was adopted here for electric potential. The fluid flow across the electrolyte medium and PEL is governed by the Stokes equation and the Darcy-Brinkman equation, respectively. The Kuwabara's unit cell model (J. Phys. Soc. Japan, 1959, 14, 522-527) was invoked to observe the effect of the interaction between the neighboring particles in a concentrated suspension. A first order perturbation technique was used to determine the mean electrophoretic mobility of the undertaken soft particles in a concentrated suspension. The effect of pH and concentration of bulk electrolyte, electrohydrodynamic properties of both the inner core and PEL, on the mean electrophoretic mobility has been studied extensively. In addition, the results have been presented for the neutralization factor that measures the fraction of fixed charges neutralized by the mobile counterions.
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Affiliation(s)
- Saurabh Kumar Maurya
- Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108, India
| | - Partha P Gopmandal
- Department of Mathematics, National Institute of Technology Durgapur, Durgapur 713209, India
| | - Simanta De
- Department of Mathematics, University of Gour Banga, Malda 732103, India
| | - H Ohshima
- Faculty of Pharmaceutical Sciences, Tokyo University of Science Noda, Chiba 278-8510, Japan
| | - Sankar Sarkar
- Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108, India
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5
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Ohshima H. Approximate analytic expressions for the electrophoretic mobility of spherical soft particles. Electrophoresis 2020; 42:2182-2188. [PMID: 33332593 DOI: 10.1002/elps.202000339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/10/2020] [Accepted: 12/11/2020] [Indexed: 11/11/2022]
Abstract
Approximate analytic expressions are derived for the electrophoretic mobility of a weakly charged spherical soft particle consisting of the particle core covered with a surface layer of polymers in an electrolyte solution. The particle core and the surface polymer layer may be charged or uncharged. The obtained electrophoretic mobility expressions, which involve neither numerical integration nor exponential integrals, are found to be in excellent agreement with the exact numerical results. It is also found that the obtained mobility expressions reproduce all the previously derived limiting expressions and approximate analytic expressions for the electrophoretic mobility of a weakly charged spherical soft particle.
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Affiliation(s)
- Hiroyuki Ohshima
- Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
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Ahualli S, Bermúdez S, Carrique F, Jiménez ML, Delgado ÁV. AC Electrokinetics of Salt-Free Multilayered Polymer-Grafted Particles. Polymers (Basel) 2020; 12:E2097. [PMID: 32942664 PMCID: PMC7569943 DOI: 10.3390/polym12092097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 11/20/2022] Open
Abstract
Interest in the electrical properties of the interface between soft (or polymer-grafted) nanoparticles and solutions is considerable. Of particular significance is the case of polyelectrolyte-coated particles, mainly taking into account that the layer-by-layer procedure allows the control of the thickness and permeability of the layer, and the overall charge of the coated particle. Like in simpler systems, electrokinetic determinations in AC fields (including dielectric dispersion in the 1 kHz-1 MHz frequency range and dynamic electrophoresis by electroacoustic methods in the 1-18 MHz range) provide a large amount of information about the physics of the interface. Different models have dealt with the electrokinetics of particles coated by a single polymer layer, but studies regarding multi-layered particles are far scarcer. This is even more significant in the case of so-called salt-free systems; ideally, the only charges existing in this case consist of the charge in the layer(s) and the core particle itself, and their corresponding countercharges, with no other ions added. The aims of this paper are as follows: (i) the elaboration of a model for the evaluation of the electrokinetics of multi-grafted polymer particles in the presence of alternating electric fields, in dispersion media where no salts are added; (ii) to carry out an experimental evaluation of the frequency dependence of the dynamic (or AC) electrophoretic mobility and the dielectric permittivity of suspensions of polystyrene latex spherical particles coated with successive layers of cationic, anionic, and neutral polymers; and (iii) finally, to perform a comparison between predictions and experimental results, so that it can be demonstrated that the electrokinetic analysis is a useful tool for the in situ characterization of multilayered particles.
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Affiliation(s)
- Silvia Ahualli
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
| | - Sara Bermúdez
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
| | - Félix Carrique
- Department of Applied Physics I, School of Sciences, University of Málaga, 23071 Málaga, Spain;
| | - María L. Jiménez
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
| | - Ángel V. Delgado
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
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7
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Lai YC, Keh HJ. Transient electrophoresis of a charged porous particle. Electrophoresis 2020; 41:259-265. [DOI: 10.1002/elps.201900413] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/29/2019] [Accepted: 12/23/2019] [Indexed: 11/05/2022]
Affiliation(s)
- Yi C. Lai
- Department of Chemical EngineeringNational Taiwan University Taipei Taiwan
| | - Huan J. Keh
- Department of Chemical EngineeringNational Taiwan University Taipei Taiwan
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8
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Ashrafizadeh SN, Seifollahi Z, Ganjizade A, Sadeghi A. Electrophoresis of spherical soft particles in electrolyte solutions: A review. Electrophoresis 2019; 41:81-103. [DOI: 10.1002/elps.201900236] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 11/11/2019] [Accepted: 11/11/2019] [Indexed: 02/01/2023]
Affiliation(s)
- Seyed Nezameddin Ashrafizadeh
- Research Lab for Advanced Separation ProcessesDepartment of Chemical EngineeringIran University of Science and Technology Tehran Iran
| | - Zahra Seifollahi
- Research Lab for Advanced Separation ProcessesDepartment of Chemical EngineeringIran University of Science and Technology Tehran Iran
| | - Ardalan Ganjizade
- Research Lab for Advanced Separation ProcessesDepartment of Chemical EngineeringIran University of Science and Technology Tehran Iran
| | - Arman Sadeghi
- Department of Mechanical EngineeringUniversity of Kurdistan Sanandaj Iran
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Khandelwal AV, Singh A, Pal N, Kumar R, Goel G, Gupta S. AC Conductivity Measurements of Ultradilute Colloidal Suspensions in HEPES Buffer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:14725-14733. [PMID: 31626736 DOI: 10.1021/acs.langmuir.9b01464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Impedance spectroscopy was used to probe the AC conductivity of extremely dilute colloidal suspensions (2.5 × 10-5 ≤ Φw/v ≤ 4.0 × 10-2) comprising of polystyrene microspheres (PS; κa ≫ 1 and ζ = -65 mV), gold nanoparticles (Au NPs; κa > 1 and ζ = -26 mV), and Au-coated PS metallodielectric particles (Au-PS) in HEPES buffer. When AC electric fields of strength 10 mV and 1 MHz were applied via 100 μm gap interdigitated microelectrodes across 10 μL samples, a highly resistive (θcapacitive < 1°) and nonmonotonic response was obtained with particle concentrations at steady state. While the suspensions were less resistive (than the buffer) below a critical concentration, they became more resistive above it. More interestingly, particle-particle interactions took place in suspensions with concentrations as low as 0.005% w/v. We believe this unique behavior is linked to the ion size asymmetry in the HEPES molecule that provides an ideal microenvironment for counterionic polarization around the particles. The exact mechanism of polarization in HEPES, however, still remains elusive as the current theoretical models for simple electrolytes fail to explain our data.
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Affiliation(s)
- Aditya Vikram Khandelwal
- Department of Chemical Engineering , Indian Institute of Technology Delhi , New Delhi 110016 , India
| | - Akash Singh
- Department of Chemical Engineering , Indian Institute of Technology Delhi , New Delhi 110016 , India
| | - Namrata Pal
- Department of Chemical Engineering , Indian Institute of Technology Delhi , New Delhi 110016 , India
| | - Rajdeep Kumar
- Department of Chemical Engineering , Indian Institute of Technology Delhi , New Delhi 110016 , India
| | - Gaurav Goel
- Department of Chemical Engineering , Indian Institute of Technology Delhi , New Delhi 110016 , India
| | - Shalini Gupta
- Department of Chemical Engineering , Indian Institute of Technology Delhi , New Delhi 110016 , India
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Poltronieri P, Primiceri E, Radhakrishnan R. EIS-Based Biosensors in Foodborne Pathogen Detection with a Special Focus on Listeria monocytogenes. Methods Mol Biol 2019; 1918:87-101. [PMID: 30580401 DOI: 10.1007/978-1-4939-9000-9_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this chapter methods and protocols for surfaces adapted to electrochemical impedance detection, antibody binding, electrolyte couples used, and instrumentation for EIS Biosensing are presented. Various technical bottlenecks have been overcome in recent years. Other limitations still present in this technique are discussed. We present the most recent applications in food pathogen detection based on EIS methods, as well as using other antibody-based platforms.
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12
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Ionic coupling effects in dynamic electrophoresis and electric permittivity of aqueous concentrated suspensions. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Radhakrishnan R, Poltronieri P. Fluorescence-Free Biosensor Methods in Detection of Food Pathogens with a Special Focus on Listeria monocytogenes. BIOSENSORS 2017; 7:E63. [PMID: 29261134 PMCID: PMC5746786 DOI: 10.3390/bios7040063] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/11/2017] [Accepted: 12/18/2017] [Indexed: 12/16/2022]
Abstract
Food pathogens contaminate food products that allow their growth on the shelf and also under refrigerated conditions. Therefore, it is of utmost importance to lower the limit of detection (LOD) of the method used and to obtain the results within hours to few days. Biosensor methods exploit the available technologies to individuate and provide an approximate quantification of the bacteria present in a sample. The main bottleneck of these methods depends on the aspecific binding to the surfaces and on a change in sensitivity when bacteria are in a complex food matrix with respect to bacteria in a liquid food sample. In this review, we introduce surface plasmon resonance (SPR), new advancements in SPR techniques, and electrochemical impedance spectroscopy (EIS), as fluorescence-free biosensing technologies for detection of L. monocytogenes in foods. The application of the two methods has facilitated L. monocytogenes detection with LOD of 1 log CFU/mL. Further advancements are envisaged through the combination of biosensor methods with immunoseparation of bacteria from larger volumes, application of lab-on-chip technologies, and EIS sensing methods for multiplex pathogen detection. Validation efforts are being conducted to demonstrate the robustness of detection, reproducibility and variability in multi-site installations.
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Ahualli S, Iglesias GR, Fernández MM, Jiménez ML, Delgado ÁV. Use of Soft Electrodes in Capacitive Deionization of Solutions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:5326-5333. [PMID: 28368580 DOI: 10.1021/acs.est.6b06181] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
All efforts to obtain, reuse or purify water are extremely significant for society. Recently, researchers have begun to delve in an idea born decades ago: the desalination of water using highly porous electrodes. It is based on a fundamental aspect of electrical double layers, namely, their huge capacitance. The ions of a solution can be partially removed under the application of an electric field when the solution fills the space between porous electrodes, either bare (CDI, or capacitive deionization), coated with ionic exchange membranes (MCDI) or chemically treated (inverted-CDI or i-CDI). One of the challenges of the last years was to explore new materials and arrangements to improve the efficiency of the system. In this work, we propose a new approach inspired in the electrokinetics of soft particles: a layer of polyelectrolyte (cationic on one electrode, anionic on the opposite one) coats the carbon electrodes, converting them in a sort of "soft" electrode pair. We present a theoretical model and a set of experiments showing how soft electrodes can be successfully employed in capacitive deionization.
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Affiliation(s)
- Silvia Ahualli
- Department of Applied Physics, School of Science, Campus Fuentenueva University of Granada , 18071 Granada, Spain
| | - Guillermo R Iglesias
- Department of Applied Physics, School of Science, Campus Fuentenueva University of Granada , 18071 Granada, Spain
| | - María M Fernández
- Department of Applied Physics, School of Science, Campus Fuentenueva University of Granada , 18071 Granada, Spain
| | - María L Jiménez
- Department of Applied Physics, School of Science, Campus Fuentenueva University of Granada , 18071 Granada, Spain
| | - Ángel V Delgado
- Department of Applied Physics, School of Science, Campus Fuentenueva University of Granada , 18071 Granada, Spain
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Mohanty PS, Nöjd S, Bergman MJ, Nägele G, Arrese-Igor S, Alegria A, Roa R, Schurtenberger P, Dhont JKG. Dielectric spectroscopy of ionic microgel suspensions. SOFT MATTER 2016; 12:9705-9727. [PMID: 27808335 DOI: 10.1039/c6sm01683a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The determination of the net charge and size of microgel particles as a function of their concentration, as well as the degree of association of ions to the microgel backbone, has been pursued in earlier studies mainly by scattering and rheology. These methods suffer from contributions due to inter-particle interactions that interfere with the characterization of single-particle properties. Here we introduce dielectric spectroscopy as an alternative experimental method to characterize microgel systems. The advantage of dielectric spectroscopy over other experimental methods is that the polarization due to mobile charges within a microgel particle is only weakly affected by inter-particle interactions. Apart from electrode polarization effects, experimental spectra on PNIPAM-co-AA [poly(N-isopropylacrylamide-co-acrylic acid)] ionic microgel particles suspended in de-ionized water exhibit three well-separated relaxation modes, which are due to the polarization of the mobile charges within the microgel particles, the diffuse double layer around the particles, and the polymer backbone. Expressions for the full frequency dependence of the electrode-polarization contribution to the measured dielectric response are derived, and a theory is proposed for the polarization resulting from the mobile charges within the microgel. Relaxation of the diffuse double layer is modeled within the realm of a cell model. The net charge and the size of the microgel particles are found to be strongly varying with concentration. A very small value of the diffusion coefficient of ions within the microgel is found, due to a large degree of chemical association of protons to the polymer backbone.
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Affiliation(s)
- P S Mohanty
- Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden and School of Applied Sciences, KIIT University, Bhubaneswar 751024, India
| | - S Nöjd
- Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden
| | - M J Bergman
- Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden
| | - G Nägele
- Institute of Complex Systems ICS-3, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. and Heinrich-Heine Universität Düsseldorf, Department of Physics, D-40225 Düsseldorf, Germany and JARA-SOFT, 52425 Jülich, Germany
| | - S Arrese-Igor
- Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center, 20018 San Sebastián, Spain
| | - A Alegria
- Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center, 20018 San Sebastián, Spain and Universidad del País Vasco (UPV/EHU), Departamento de Física de Materiales, 20080 San Sebastián, Spain
| | - R Roa
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
| | - P Schurtenberger
- Division of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden
| | - J K G Dhont
- Institute of Complex Systems ICS-3, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. and Heinrich-Heine Universität Düsseldorf, Department of Physics, D-40225 Düsseldorf, Germany and JARA-SOFT, 52425 Jülich, Germany
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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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Li WC, Keh HJ. Electrophoretic mobility of charged porous shells or microcapsules and electric conductivity of their dilute suspensions. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.02.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Liu HC, Keh HJ. Electrophoresis and electric conduction in a suspension of charged soft particles. Colloid Polym Sci 2016. [DOI: 10.1007/s00396-016-3863-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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19
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Sagou JPS, Ahualli S, Thomas F. Influence of ionic strength and polyelectrolyte concentration on the electrical conductivity of suspensions of soft colloidal polysaccharides. J Colloid Interface Sci 2015; 459:212-217. [DOI: 10.1016/j.jcis.2015.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 08/01/2015] [Indexed: 10/23/2022]
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Chiang CC, Keh HJ. Transient electroosmosis in the transverse direction of a fibrous porous medium. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.06.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Wu H, Zhao K. Dielectric Relaxation of Spherical Polyelectrolyte Brushes: Movement of Counterions and Electrical Properties of the Brush Layer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:8566-8576. [PMID: 26172222 DOI: 10.1021/acs.langmuir.5b01408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Dielectric behaviors of spherical polyelectrolyte brush (SPB) suspensions under various mass fractions of SPB and the pH of solution were investigated in a frequency range of 40 Hz to 110 MHz. The SPB consists of a polystyrene (PS) core grafted with poly(acrylic acid) (PAA) chains. Two unique relaxations were found at either about 10 kHz or 1-10 MHz, respectively, with the former due to the diffusion of counterions and the latter resulting from the interfacial polarization. Using dielectric parameters of two relaxations, we obtained information about the migration of counterion and the conformation of polyelectrolyte chains. The PAA chains are fully stretched when pH is about 8 under the domination of the equilibrium between the penetration and diffusion of counterions in the brushes. A dielectric model is proposed to describe the high-frequency relaxation, and the permittivity and conductivity of SPB and its volume fraction were also calculated on the basis of the model. The surface conductivity of SPB, the Donnan potential, and the fixed charge density in the brush layer were derived from these paramaters. The distribution of the Donnan potential was also simulated by using Poisson-Boltzmann equations, and the result is in accordance with these obtained on the basis of the dielectric model.
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Affiliation(s)
- Haiyan Wu
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Kongshuang Zhao
- College of Chemistry, Beijing Normal University, Beijing 100875, China
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22
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Electrophoretic mobility and electric conductivity in suspensions of charge-regulating porous particles. Colloid Polym Sci 2015. [DOI: 10.1007/s00396-015-3580-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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23
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Mavrogiannis N, Desmond M, Gagnon ZR. Fluidic dielectrophoresis: The polarization and displacement of electrical liquid interfaces. Electrophoresis 2015; 36:1386-95. [DOI: 10.1002/elps.201400454] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 11/29/2014] [Accepted: 12/03/2014] [Indexed: 02/04/2023]
Affiliation(s)
- Nicholas Mavrogiannis
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University Baltimore; Baltimore MD USA
| | - Mitchell Desmond
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University Baltimore; Baltimore MD USA
| | - Zachary R. Gagnon
- Department of Chemical and Biomolecular Engineering; Johns Hopkins University Baltimore; Baltimore MD USA
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24
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Huang HY, Keh HJ. Diffusiophoresis in Suspensions of Charged Porous Particles. J Phys Chem B 2015; 119:2040-50. [DOI: 10.1021/jp510448x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hsin Y. Huang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Huan J. Keh
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan, Republic of China
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25
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Ahualli S, Fernández MM, Iglesias G, Delgado ÁV, Jiménez ML. Temperature effects on energy production by salinity exchange. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:12378-12385. [PMID: 25230095 DOI: 10.1021/es500634f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In recent years, the capacitance of the interface between charged electrodes and ionic solutions (the electric double layer) has been investigated as a source of clean energy. Charge is placed on the electrodes either by means of ion-exchange membranes or of an external power source. In the latter method, net energy is produced by simple solution exchange in open circuit, due to the associated decrease in the capacitance of the electric double layer. In this work, we consider the change in capacitance associated with temperature variations: the former decreases when temperature is raised, and, hence, a cycle is possible in which some charge is put on the electrode at a certain potential and returned at a higher one. We demonstrate experimentally that it is thus viable to obtain energy from electric double layers if these are successively contacted with water at different temperatures. In addition, we show theoretically and experimentally that temperature and salinity variations can be conveniently combined to maximize the electrode potential increase. The resulting available energy is also estimated.
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Affiliation(s)
- Silvia Ahualli
- Department of Applied Physics, School of Sciences, University of Granada , 18071 Granada, Granada, Spain
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26
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Chen GY, Keh HJ. Start-up of electrophoresis of an arbitrarily oriented dielectric cylinder. Electrophoresis 2014; 35:2560-5. [DOI: 10.1002/elps.201400184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/10/2014] [Accepted: 06/12/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Guan Y. Chen
- Department of Chemical Engineering; National Taiwan University; Taipei Taiwan ROC
| | - Huan J. Keh
- Department of Chemical Engineering; National Taiwan University; Taipei Taiwan ROC
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Merlin J, Duval JFL. Electrodynamics of soft multilayered particles dispersions: dielectric permittivity and dynamic mobility. Phys Chem Chem Phys 2014; 16:15173-88. [DOI: 10.1039/c4cp01674b] [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
A theory is presented for the electrodynamics of dispersions of spherical soft multilayered (bio)particles consisting of a hard core surrounded by step-function or diffuse-like polymeric layers with distinct electrohydrodynamic and structural features.
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Affiliation(s)
- Jenny Merlin
- Université de Lorraine
- Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC)
- Vandœuvre-lès-Nancy, France
- CNRS
- Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC)
| | - Jérôme F. L. Duval
- Université de Lorraine
- Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC)
- Vandœuvre-lès-Nancy, France
- CNRS
- Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC)
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28
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Sedimentation velocity and potential in a concentrated suspension of charged soft spheres. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2012.08.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Ohshima H. Electrophoretic mobility of soft particles. A soft step function model. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2012.09.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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30
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Ahualli S, Jiménez ML, Fernández MM, Iglesias G, Brogioli D, Delgado ÁV. Polyelectrolyte-coated carbons used in the generation of blue energy from salinity differences. Phys Chem Chem Phys 2014; 16:25241-6. [DOI: 10.1039/c4cp03527e] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polyelectrolyte-coated carbon films are used as electrodes for energy extraction from salinity exchange.
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Affiliation(s)
- S. Ahualli
- Department of Applied Physics
- School of Sciences
- University of Granada
- Granada, Spain
| | - M. L. Jiménez
- Department of Applied Physics
- School of Sciences
- University of Granada
- Granada, Spain
| | - M. M. Fernández
- Department of Applied Physics
- School of Sciences
- University of Granada
- Granada, Spain
| | - G. Iglesias
- Department of Applied Physics
- School of Sciences
- University of Granada
- Granada, Spain
| | - D. Brogioli
- Dipartimento di Scienze della Salute
- Universit degli Studi di Milano-Bicocca
- Monza (MB) 20900, Italy
| | - Á. V. Delgado
- Department of Applied Physics
- School of Sciences
- University of Granada
- Granada, Spain
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31
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Carrique F, Ruiz-Reina E, Lechuga L, Arroyo FJ, Delgado ÁV. Effects of non-equilibrium association-dissociation processes in the dynamic electrophoretic mobility and dielectric response of realistic salt-free concentrated suspensions. Adv Colloid Interface Sci 2013; 201-202:57-67. [PMID: 24161224 DOI: 10.1016/j.cis.2013.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 10/04/2013] [Accepted: 10/05/2013] [Indexed: 10/26/2022]
Abstract
Electrokinetic investigations in nanoparticle suspensions in aqueous media are most often performed assuming that the liquid medium is a strong electrolyte solution with specified concentration. The role of the ions produced by the process of charging the surfaces of the particles is often neglected or, at most, the concentrations of such ions are estimated in some way and added to the concentrations of the ions in the externally prepared solution. The situation here considered is quite different: no electrolyte is dissolved in the medium, and ideally only the counterions stemming from the particle charging are assumed to be in solution. This is the case of so-called salt-free systems. With the aim of making a model for such kind of dispersions as close to real situations as possible, it was previously found to consider the unavoidable presence of H(+) and OH(-) coming from water dissociation, as well as the (almost unavoidable) ions stemming from the dissolution of atmospheric CO2. In this work, we extend such approach by considering that the chemical reactions involved in dissociation and recombination of the (weak) electrolytes in solution must not necessarily be in equilibrium conditions (equal rates of forward and backward reactions). To that aim, we calculate the frequency spectra of the electric permittivity and dynamic electrophoretic mobility of salt-free suspensions considering realistic non-equilibrium conditions, using literature values for the rate constants of the reactions. Four species are linked by such reactions, namely H(+) (from water, from the--assumed acidic--groups on the particle surfaces, and from CO2 dissolution), OH(-) (from water), HCO3(-) and H2CO3 (again from CO2). A cell model is used for the calculations, which are extended to arbitrary values of the surface charge, the particle size, and particle volume fraction, in a wide range of the field frequency ω. Both approaches predict a high frequency relaxation of the counterion condensated layer and a Maxwell-Wagner-O'Konski electric double layer relaxation at intermediate frequencies. Also, in both cases an inertial decay of the electrophoretic mobility at high ω takes place. The most significant difference between the present model and previous results based on the equilibrium hypothesis is by no means negligible: only in non-equilibrium conditions do we find a low-frequency relaxation (mostly noticed in permittivity data, while its significance is lower in dynamic mobility spectra). This new relaxation presents all the characteristic features of the concentration polarization (or alpha) dispersion. These are: i) the average electric polarization of the system increases when the relaxation frequency is surpassed, contrary to the behavior after Maxwell-Wagner type relaxations; ii) the amplitude of the relaxation increases with surface charge, reaching a sort of saturation if the charge is too high; iii) the relaxation frequency increases with volume fraction while the relaxation amplitude decreases; iv) the characteristic frequency is reduced by the increase in particle radius. All these facts confirm that the non-equilibrium approach seems to better describe the physics of the system by giving rise to a concentration polarization kind of relaxation, only possible when ions can accumulate on both sides of the particles as dictated by the field, and not as determined by equilibrium conditions in the dissociation-recombination reactions involved.
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32
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Chang YJ, Keh HJ. Sedimentation of a charged porous particle in a charged cavity. J Phys Chem B 2013; 117:12319-27. [PMID: 24041255 DOI: 10.1021/jp407805x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sedimentation of a charged porous sphere at the center of a charged spherical cavity filled with an electrolyte solution is analyzed. The thickness of the electric double layers around the particle and cavity wall is arbitrary, and their relaxation effect is considered. Through the use of a set of linearized electrokinetic equations and a perturbation method, the ionic electrochemical potential energy, electric potential, and velocity fields in the fluid are solved with the fixed space charge density of the particle and surface charge density of the cavity as the small perturbation parameters, and an explicit formula for the sedimentation velocity is obtained. Due to the electroosmotic enhancement on the fluid recirculation in the cavity caused by the sedimentation-induced electric field, the presence of the surface charges on the cavity wall increases the sedimentation velocity of the porous particle. For the sedimentation of a porous particle in a cavity with their fixed charges of the same sign, the effect of electric interaction between the particle and cavity wall in general increases the sedimentation velocity. For the case of their fixed charges with opposite signs, the sedimentation velocity is increased/reduced if the magnitude of the fixed charge density of the cavity wall is relatively large/small. The effect of the surface charges at the cavity wall on the sedimentation of the porous particle increases with an increase in the permeability for fluid flow within the particle and with a decrease in the particle-to-cavity radius ratio (i.e., an increase in the surface area of the cavity wall relative to a given size of the particle, which enhances the fluid recirculation effect).
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Affiliation(s)
- Ya J Chang
- Department of Chemical Engineering, National Taiwan University , Taipei 10617, Taiwan, Republic of China
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33
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Chen WJ, Keh HJ. Electrophoresis of a Charged Soft Particle in a Charged Cavity with Arbitrary Double-Layer Thickness. J Phys Chem B 2013; 117:9757-67. [DOI: 10.1021/jp405357e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wei J. Chen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan, Republic of
China
| | - Huan J. Keh
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan, Republic of
China
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34
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Predictions of the maximum energy extracted from salinity exchange inside porous electrodes. J Colloid Interface Sci 2013; 402:340-9. [DOI: 10.1016/j.jcis.2013.03.068] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 11/24/2022]
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35
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36
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Cui H, Li S, Yuan Q, Wadhwa A, Eda S, Chambers M, Ashford R, Jiang H, Wu J. An AC electrokinetic impedance immunosensor for rapid detection of tuberculosis. Analyst 2013; 138:7188-96. [DOI: 10.1039/c3an01112g] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Ahualli S, Ballauff M, Arroyo FJ, Delgado ÁV, Jiménez ML. Electrophoresis and dielectric dispersion of spherical polyelectrolyte brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:16372-16381. [PMID: 23110617 DOI: 10.1021/la302483e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Spherical polyelectrolyte brushes (SPBs) consist of a rigid core on which polyelectrolyte chains are grafted in such a way that in certain conditions (low ionic strength and high charge of the chains) the polymer chains extend radially toward the liquid medium. Because of the hairy-like structure of the polymer brushes, the typical soft-particle approach used for explaining the behavior of polyelectrolyte-coated particles must be modified, using the assumptions that the density of charged segments in the polymer chains decreases with the squared distance to the rigid core surface and that the same happens to the friction between the brushes and the surrounding fluid. Interest in clarifying the electrokinetics of these systems is not just academic. It has recently been found experimentally (Jiménez et al., Soft Matter 2011, 7, 3758-3762) that the response of concentrated suspensions of spherical polyelectrolyte brushes in the presence of alternating electric fields shows a number of unexpected features. Both dielectric and dynamic electrophoretic mobility spectra (respectively, dependences of the electric permittivity and the AC electrophoretic mobility on the frequency of the applied field) showed very special aspects, with giant values of the mobility and an unusually strong dielectric relaxation in the kHz region. In the present paper we give a full account of the electrodynamics of such systems, based on a cell model for describing the hydrodynamic and electrical interactions between the particles. It is found that the low-frequency dynamic mobility of SPBs is much higher than that of rigid particles of comparable size and charge, making any interpretation based on zeta potential estimations of very limited applicability. The very characteristic feature of SPBs in concentrated suspensions, namely, the enhanced alpha relaxation, can be explained by considering an adequate description of the field-induced perturbations in the counterion and co-ion concentrations, well developed both outside and inside the soft layer in the case of brush-coated particles. It can be also pointed out that the dynamic electrophoretic mobility of SPBs increases with the volume fraction of particles, as a consequence of the large thickness of the brush. Predictions are also shown for the effects of friction coefficient and charge of the polyelectrolyte layer. The results compare well with experimental spectra of the dynamic mobility and electric permittivity of moderately concentrated suspensions of SPBs consisting of a 50 nm polystyrene core with grafted poly(styrene sulfonate) chains some 140 nm in length.
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Affiliation(s)
- Silvia Ahualli
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain
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38
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Uppapalli S, Zhao H. Polarization of a diffuse soft particle subjected to an alternating current field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11164-11172. [PMID: 22758794 DOI: 10.1021/la301889e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The polarization of a diffuse soft particle submerged in an aqueous electrolyte and subjected to a uniform alternating electric field is theoretically analyzed with the standard electrokinetic model (the Poisson-Nernst-Planck equations). The particle consists of a rigid uncharged core and a charged diffuse polyelectrolytic shell (soft layer) permeable to ions and solvent. Our focus is on the impact of the characteristics of the soft layer including the Donnan potential, the soft layer thickness, and the friction coefficient of the soft layer on the dipole coefficient, characterizing the strength of the polarization. Under the limits of thin double layers and thin polyelectrolytic shells, approximate analytical expressions to evaluate the dipole moment coefficients are derived for high-frequency and low-frequency ranges, respectively. The analytical results are compared and agree favorably with those numerically computed by the standard model. Interestingly, we discover that when the double layer is comparable to the soft layer the dipole moment behaves qualitatively differently at different Donnan potentials. When the Donnan potential is small, the dipole moment decreases as the double layer increases. In contrast, at large Donnan potentials, the dipole moment increases with the increase in the double layer. The distinct responses to Donnan potentials are attributed to the impact of the associated double layer on the charge distribution of mobile ions inside the soft layer. The theoretical model provides a fundamental basis for interpreting the polarization of heterogeneous systems, including environmental or biological colloids or microgel particles.
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Affiliation(s)
- Sebastian Uppapalli
- Department of Mechanical Engineering, University of Nevada, Las Vegas, Nevada 89154, United States
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39
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Louie SM, Phenrat T, Small MJ, Tilton RD, Lowry GV. Parameter identifiability in application of soft particle electrokinetic theory to determine polymer and polyelectrolyte coating thicknesses on colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10334-10347. [PMID: 22708677 DOI: 10.1021/la301912j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Soft particle electrokinetic models have been used to determine adsorbed nonionic polymer and polyelectrolyte layer properties on nanoparticles or colloids by fitting electrophoretic mobility data. Ohshima first established the formalism for these models and provided analytical approximations ( Ohshima, H. Adv. Colloid Interface Sci.1995, 62, 189 ). More recently, exact numerical solutions have been developed, which account for polarization and relaxation effects and require fewer assumptions on the particle and soft layer properties. This paper characterizes statistical uncertainty in the polyelectrolyte layer charge density, layer thickness, and permeability (Brinkman screening length) obtained from fitting data to either the analytical or numerical electrokinetic models. Various combinations of particle core and polymer layer properties are investigated to determine the range of systems for which this analysis can provide a solution with reasonably small uncertainty bounds, particularly for layer thickness. Identifiability of layer thickness in the analytical model ranges from poor confidence for cases with thick, highly charged coatings, to good confidence for cases with thin, low-charged coatings. Identifiability is similar for the numerical model, except that sensitivity is improved at very high charge and permeability, where polarization and relaxation effects are significant. For some poorly identifiable cases, parameter reduction can reduce collinearity to improve identifiability. Analysis of experimental data yielded results consistent with expectations from the simulated theoretical cases. Identifiability of layer charge density and permeability is also evaluated. Guidelines are suggested for evaluation of statistical confidence in polymer and polyelectrolyte layer parameters determined by application of the soft particle electrokinetic theory.
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Affiliation(s)
- Stacey M Louie
- Center for the Environmental Implications of NanoTechnology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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40
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Ohshima H. Electrical Phenomena of Soft Particles. A Soft Step Function Model. J Phys Chem A 2012; 116:6473-80. [DOI: 10.1021/jp212002e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hiroyuki Ohshima
- Faculty of Pharmaceutical
Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510,
Japan, and Center for Colloid and Interface Science, Research Institute
for Science and Technology, Tokyo University of Science, 2641 Yamazaki,
Noda, Chiba 278-8510, Japan
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41
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Rong Z, Feng Q. How Insoluble Particles Affect the Solutions’ Conductivity: A Theory and the Test in NaCl and Chitosan Solutions. J Phys Chem B 2011; 115:12816-21. [DOI: 10.1021/jp202432u] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ziqin Rong
- Laboratory of Advanced Material, Department of Material Science and Engineering, Tsinghua University, Beijing 100084, P.R. China
| | - Qingling Feng
- Laboratory of Advanced Material, Department of Material Science and Engineering, Tsinghua University, Beijing 100084, P.R. China
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42
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Viota JL, Rudzka K, Trueba Á, Torres-Aleman I, Delgado ÁV. Electrophoretic characterization of insulin growth factor (IGF-1) functionalized magnetic nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:6426-6432. [PMID: 21506536 DOI: 10.1021/la2009144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The synthesis of composite nanoparticles consisting of a magnetite core coated with a layer of the hormone insulin growth factor 1 (IGF-1) is described. The adsorption of the hormone in the different formulations is first studied by electrophoretic mobility measurements as a function of pH, ionic strength, and time. Because of the permeable character expected for both citrate and IGF-1 coatings surrounding the magnetite cores, an appropriate analysis of their electrophoretic mobility must be addressed. Recent developments of electrokinetic theories for particles covered by soft surface layers have rendered possible the evaluation of the softness degree from raw electrophoretic mobility data. In the present contribution, the data are quantitatively analyzed based on the theoretical model of the electrokinetics of soft particles. As a result, information is obtained on both the thickness and the charge density of the surrounding layer. It is shown that IGF-1 adsorbs onto the surface of citrate-coated magnetite nanoparticles, and adsorption is confirmed by dot-blot analysis. In addition, it is also demonstrated that the external layer of IGF-1 exerts a shielding effect on the surface charge of citrate-magnetite particles, as suggested by the mobility reduction upon contacting the particles with the hormone. Aging effects are demonstrated, providing an electrokinetic fingerprint of changes in adsorbed protein configuration with time.
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Affiliation(s)
- Julián L Viota
- Department of Physics, Campus Las Lagunillas, University of Jaén, 23071, Jaén, Spain.
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43
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Ohshima H. Electrophoretic mobility of a highly charged soft particle: Relaxation effect. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2010.09.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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44
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Roa R, Carrique F, Ruiz-Reina E. dc electrokinetics for spherical particles in salt-free concentrated suspensions including ion size effects. Phys Chem Chem Phys 2011; 13:19437-48. [DOI: 10.1039/c1cp22359c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Koupanou E, Ahualli S, Glatter O, Delgado A, Krumeich F, Leontidis E. Stabilization of lead sulfide nanoparticles by polyamines in aqueous solutions. A structural study of the dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:16909-16920. [PMID: 20945867 DOI: 10.1021/la1031366] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Lead sulfide (PbS) nanoparticles have been synthesized in aqueous solutions by a reaction between inorganic lead salts and sodium sulfide and stabilized using the cationic polyelectrolytes branched poly(ethylenimine) (PEI), poly(allylamine hydrochloride) (PAH), and poly(diallyldimethylammonium chloride) (PDDA). The structures of the polyamine-stabilized nanoparticle dispersions were examined in detail using UV-vis spectroscopy, small-angle X-ray scattering (SAXS), static and dynamic electrophoretic mobility measurements, and transmission electron microscopy (TEM). Considerable differences were found between the stabilizing efficiencies of these polyelectrolytes, which cannot be attributed to their charge densities or their persistence lengths. Small monodisperse nanoparticles of PbS with a tight stabilizing shell were consistently found only when PEI was used as a stabilizer even at high pH values, although its charge density is then very low. The excellence of PEI as a stabilizer is mainly due to the extensive branching of the chains and the presence of uncharged secondary and tertiary amine groups, which apparently serve as good anchoring points at the nanoparticle surfaces. None of the polyelectrolytes examined here provide long-term protection of the nanoparticles toward oxidation by air, showing that a need for more complex multipurpose stabilizers exists for aqueous PbS dispersions.
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Affiliation(s)
- Elena Koupanou
- Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
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46
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