1
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Gallegos A, Müller M, Wu J. Single-chain simulation of Ising density functional theory for weak polyelectrolytes. J Chem Phys 2023; 159:214902. [PMID: 38047517 DOI: 10.1063/5.0175561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/02/2023] [Indexed: 12/05/2023] Open
Abstract
Conventional theories of weak polyelectrolytes are either computationally prohibitive to account for the multidimensional inhomogeneity of polymer ionization in a liquid environment or oversimplistic in describing the coupling effects of ion-explicit electrostatic interactions and long-range intrachain correlations. To bridge this gap, we implement the Ising density functional theory (iDFT) for ionizable polymer systems using the single-chain-in-mean-field algorithm. The single-chain-in-iDFT (sc-iDFT) shows significant improvements over conventional mean-field methods in describing segment-level dissociation equilibrium, specific ion effects, and long-range intrachain correlations. With an explicit consideration of the fluctuations of polymer configurations and the position-dependent ionization of individual polymer segments, sc-iDFT provides a faithful description of the structure and thermodynamic properties of inhomogeneous weak polyelectrolyte systems across multiple length scales.
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Affiliation(s)
- Alejandro Gallegos
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
| | - Marcus Müller
- Institut für Theoretische Physik, Georg-August-Universität, 37077 Göttingen, Germany
| | - Jianzhong Wu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
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2
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Rahmaninejad H, Parnell AJ, Chen WL, Duzen N, Sexton T, Dunderdale G, Ankner JF, Bras W, Ober CK, Ryan AJ, Ashkar R. Synthesis and Characterization of Stimuli-Responsive Polymer Brushes in Nanofluidic Channels. ACS APPLIED MATERIALS & INTERFACES 2023; 15:54942-54951. [PMID: 37973616 PMCID: PMC10695172 DOI: 10.1021/acsami.3c12744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 10/20/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023]
Abstract
Nanochannels with controllable gating behavior are attractive features in a wide range of nanofluidic applications including viral detection, particle sorting, and flow regulation. Here, we use selective sidewall functionalization of nanochannels with a polyelectrolyte brush to investigate the channel gating response to variations in solution pH and ionic strength. The conformational and structural changes of the interfacial brush layer within the channels are interrogated by specular and off-specular neutron reflectometry. Simultaneous fits of the specular and off-specular signals, using a dynamical theory model and a fitting optimization protocol, enable detailed characterization of the brush conformations and corresponding channel geometry under different solution conditions. Our results indicate a collapsed brush state under basic pH, equivalent to an open gate, and an expanded brush state representing a partially closed gate upon decreasing the pH and salt concentration. These findings open new possibilities in noninvasive in situ characterization of tunable nanofluidics and lab-on-chip devices with advanced designs and improved functionality.
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Affiliation(s)
- Hadi Rahmaninejad
- Department
of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
- Center
for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Andrew J. Parnell
- Department
of Physics, The University of Sheffield, Sheffield S3 7RH, U.K.
| | - Wei-Liang Chen
- Department
of Material Science and Engineering, University
of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Nilay Duzen
- Department
of Material Science and Engineering, Cornell
University, Ithaca, New York 14850, United States
| | - Thomas Sexton
- Department
of Physics, The University of Sheffield, Sheffield S3 7RH, U.K.
| | - Gary Dunderdale
- Department
of Chemical and Biological Engineering, The University of Sheffield, Sheffield S1 3JD, U.K.
| | - John F. Ankner
- Second
Target Station, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Wim Bras
- Chemical
Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Christopher K. Ober
- Department
of Material Science and Engineering, Cornell
University, Ithaca, New York 14850, United States
| | - Anthony J. Ryan
- Department
of Chemistry, The University of Sheffield, Sheffield S3 7HF, U.K.
| | - Rana Ashkar
- Center
for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Physics, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecular Innovation Institute, Virginia
Tech, Blacksburg, Virginia 24061, United States
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3
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Gallegos A, Ong GMC, Wu J. Ising density functional theory for weak polyelectrolytes with strong coupling of ionization and intrachain correlations. J Chem Phys 2021; 155:241102. [PMID: 34972389 DOI: 10.1063/5.0066774] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report a theoretical framework for weak polyelectrolytes by combining the polymer density functional theory with the Ising model for charge regulation. The so-called Ising density functional theory provides an accurate description of the effects of polymer conformation on the ionization of individual segments and is able to account for both the intra- and interchain correlations due to the excluded-volume effects, chain connectivity, and electrostatic interactions. Theoretical predictions of the titration behavior and microscopic structure of ionizable polymers are found to be in excellent agreement with the experiment.
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Affiliation(s)
- Alejandro Gallegos
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
| | - Gary M C Ong
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
| | - Jianzhong Wu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
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4
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Gallegos A, Ong GMC, Wu J. Thermodynamic non-ideality in charge regulation of weak polyelectrolytes. SOFT MATTER 2021; 17:9221-9234. [PMID: 34596201 DOI: 10.1039/d1sm00848j] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Polymer ionization differs from that for their monomeric counterparts due to intramolecular correlations. Such effects are conventionally described in terms of the site-binding model that accounts for short-range interactions between neighboring sites. With an apparent equilibrium constant for each ionizable group and the nearest-neighbor energy as adjustable parameters, the site-binding method is useful to correlate experimental titration curves when the site-site interactions are insignificant at long ranges. This work aims to describe the electrostatic behavior of weak polyelectrolytes in aqueous solutions on the basis of the intrinsic equilibrium constants of the individual ionizable groups and solution conditions underlying the thermodynamic non-ideality. A molecular thermodynamic model is proposed for the protonation of weak polyelectrolytes by incorporating classical density functional theory into the site-binding model to account for the effects of the local ionic environment on both inter-chain and intra-chain correlations. By an extensive comparison of theoretical predictions with experimental titration curves, we demonstrate that the thermodynamic model is able to quantify the ionization behavior of weak polyelectrolytes over a broad range of molecular architectures and solution conditions.
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Affiliation(s)
- Alejandro Gallegos
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
| | - Gary M C Ong
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
| | - Jianzhong Wu
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
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5
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Eichhorn J, Gordievskaya YD, Kramarenko EY, Khokhlov AR, Schacher FH. pH-Dependent Structure of Block Copolymer Micelles Featuring a Polyampholyte Corona: A Combined Experimental and Theoretical Approach. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jonas Eichhorn
- Institute of Organic Chemistry and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Humboldtstraße 10, Jena 07743, Germany
- Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, Jena 07743, Germany
| | - Yulia D. Gordievskaya
- Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, 1-2, Moscow 119991, Russia
- A. N. Nesmeyanov Institute of Organoelement Compounds RAS, Vavilova St., 28, Moscow 119991, Russia
- Institute of Advanced Energy Related Nanomaterials, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Elena Yu. Kramarenko
- Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, 1-2, Moscow 119991, Russia
- A. N. Nesmeyanov Institute of Organoelement Compounds RAS, Vavilova St., 28, Moscow 119991, Russia
| | - Alexei R. Khokhlov
- Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, 1-2, Moscow 119991, Russia
- A. N. Nesmeyanov Institute of Organoelement Compounds RAS, Vavilova St., 28, Moscow 119991, Russia
- Institute of Advanced Energy Related Nanomaterials, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Felix H. Schacher
- Institute of Organic Chemistry and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Humboldtstraße 10, Jena 07743, Germany
- Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, Jena 07743, Germany
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6
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Prusty D, Nap RJ, Szleifer I, Olvera de la Cruz M. Charge regulation mechanism in end-tethered weak polyampholytes. SOFT MATTER 2020; 16:8832-8847. [PMID: 32901638 DOI: 10.1039/d0sm01323d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Weak polyampholytes, containing oppositely charged dissociable groups, are expected to be responsive to changes in ionic conditions. Here, we determine structural and thermodynamic properties, including the charged groups' degrees of dissociation, of end-tethered weak polyampholyte layers as a function of salt concentration, pH, and the solvent quality. For diblock weak polyampholytes grafted by their acidic blocks, we find that the acidic monomers increase their charge while the basic monomers decrease their charge with decreasing salt concentration for pH values less than the pKa value of both monomers and vice versa when the pH > pKa. This complex charge regulation occurs because the electrostatic attraction between oppositely charged blocks is stronger than the repulsion between monomers with the same charge in both good and poor solvents when the screening by salt ions is weak. This is evidenced by the retraction of the top block into the bottom layer. In the case of poor solvent conditions to the basic block (the top block), we find lateral segregation of basic monomers into micelles, forming a two-dimensional hexagonal pattern on the surface at intermediate and high pH values for monovalent salt concentrations from 0.01 to 0.1 M. When the solvent is poor to both blocks, we find lateral segregation of the grafted acidic block into lamellae with longitudinal undulations of low and high acidic monomer density. By exploiting weak block polyampholytes, our work expands the parameter space for creating responsive surfaces stable over a wide range of pH and salt concentration.
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Affiliation(s)
- D Prusty
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
| | - R J Nap
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, USA and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, USA
| | - I Szleifer
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208, USA and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, USA and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - M Olvera de la Cruz
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA. and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA and Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
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7
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Theoretical Modeling of Chemical Equilibrium in Weak Polyelectrolyte Layers on Curved Nanosystems. Polymers (Basel) 2020; 12:polym12102282. [PMID: 33027995 PMCID: PMC7601300 DOI: 10.3390/polym12102282] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 12/19/2022] Open
Abstract
Surface functionalization with end-tethered weak polyelectrolytes (PE) is a versatile way to modify and control surface properties, given their ability to alter their degree of charge depending on external cues like pH and salt concentration. Weak PEs find usage in a wide range of applications, from colloidal stabilization, lubrication, adhesion, wetting to biomedical applications such as drug delivery and theranostics applications. They are also ubiquitous in many biological systems. Here, we present an overview of some of the main theoretical methods that we consider key in the field of weak PE at interfaces. Several applications involving engineered nanoparticles, synthetic and biological nanopores, as well as biological macromolecules are discussed to illustrate the salient features of systems involving weak PE near an interface or under (nano)confinement. The key feature is that by confining weak PEs near an interface the degree of charge is different from what would be expected in solution. This is the result of the strong coupling between structural organization of weak PE and its chemical state. The responsiveness of engineered and biological nanomaterials comprising weak PE combined with an adequate level of modeling can provide the keys to a rational design of smart nanosystems.
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8
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Adame-Arana O, Weber CA, Zaburdaev V, Prost J, Jülicher F. Liquid Phase Separation Controlled by pH. Biophys J 2020; 119:1590-1605. [PMID: 33010236 DOI: 10.1016/j.bpj.2020.07.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 06/27/2020] [Accepted: 07/06/2020] [Indexed: 12/31/2022] Open
Abstract
We present a minimal model to study the effects of pH on liquid phase separation of macromolecules. Our model describes a mixture composed of water and macromolecules that exist in three different charge states and have a tendency to phase separate. This phase separation is affected by pH via a set of chemical reactions describing protonation and deprotonation of macromolecules, as well as self-ionization of water. We consider the simple case in which interactions are captured by Flory-Huggins interaction parameters corresponding to Debye screening lengths shorter than a nanometer, which is relevant to proteins inside biological cells under physiological conditions. We identify the conjugate thermodynamic variables at chemical equilibrium and discuss the effective free energy at fixed pH. First, we study phase diagrams as a function of macromolecule concentration and temperature at the isoelectric point of the macromolecules. We find a rich variety of phase diagram topologies, including multiple critical points, triple points, and first-order transition points. Second, we change the pH relative to the isoelectric point of the macromolecules and study how phase diagrams depend on pH. We find that these phase diagrams as a function of pH strongly depend on whether oppositely charged macromolecules or neutral macromolecules have a stronger tendency to phase separate. One key finding is that we predict the existence of a reentrant behavior as a function of pH. In addition, our model predicts that the region of phase separation is typically broader at the isoelectric point. This model could account for both in vitro phase separation of proteins as a function of pH and protein phase separation in yeast cells for pH values close to the isoelectric point of many cytosolic proteins.
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Affiliation(s)
- Omar Adame-Arana
- Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany
| | - Christoph A Weber
- Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany
| | - Vasily Zaburdaev
- Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany; Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany
| | - Jacques Prost
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France; Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Frank Jülicher
- Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany; Cluster of Excellence Physics of Life, Technische Universität Dresden, Dresden, Germany.
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9
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Willott JD, Murdoch TJ, Leermakers FAM, de Vos WM. Behavior of Weak Polyelectrolyte Brushes in Mixed Salt Solutions. Macromolecules 2018; 51:1198-1206. [PMID: 29472729 PMCID: PMC5814957 DOI: 10.1021/acs.macromol.7b02244] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/22/2017] [Indexed: 12/25/2022]
Abstract
![]()
Hydrophilic
and hydrophobic weak polybasic brushes immersed in
aqueous solutions of mixed salt counterions are considered using a
mean-field numerical self-consistent field approach. On top of the
solvent quality of the polymer, the counterion–solvent interactions
are accounted for by implementing Flory–Huggins interaction
parameters. We show that ion specificity within the brush can bring
about large changes in conformation. It is found that the collapse
transition of hydrophobic, weak polyelectrolyte brushes features an
intermediate two-phase state wherein a subset of chains are collapsed
in a dense layer at the substrate, while the remainder of chains are
well-solvated and strongly stretched away from the it. Besides pH
and ionic strength, solvent quality of counterions and the composition
of ions in the solvent are important control parameters for the behavior
of polyelectrolyte brushes. Increasingly hydrophobic counterions penetrate
deeper within the brush and stabilize the collapsed region, while
hydrophilic counterions do the opposite.
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Affiliation(s)
- Joshua D Willott
- Membrane Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Timothy J Murdoch
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Frans A M Leermakers
- Physical Chemistry and Soft Matter, Wageningen University and Research, Wageningen 6708 WE, The Netherlands
| | - Wiebe M de Vos
- Membrane Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
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10
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Willott JD, Murdoch TJ, Webber GB, Wanless EJ. Physicochemical behaviour of cationic polyelectrolyte brushes. Prog Polym Sci 2017. [DOI: 10.1016/j.progpolymsci.2016.09.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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11
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Léonforte F, Welling U, Müller M. Single-chain-in-mean-field simulations of weak polyelectrolyte brushes. J Chem Phys 2016; 145:224902. [PMID: 27984879 DOI: 10.1063/1.4971212] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Structural properties of brushes which are composed of weak acidic and basic polyelectrolytes are studied in the framework of a particle-based approach that implicitly accounts for the solvent quality. Using a semi-grandcanonical partition function in the framework of the Single-Chain-in-Mean-Field (SCMF) algorithm, the weak polyelectrolyte is conceived as a supramolecular mixture of polymers in different dissociation states, which are explicitly treated in the partition function and sampled by the SCMF procedure. One obtains a local expression for the equilibrium acid-base reaction responsible for the regulation of the charged groups that is also incorporated to the SCMF sampling. Coupled to a simultaneous treatment of the electrostatics, the approach is shown to capture the main features of weak polyelectrolyte brushes as a function of the bulk pH in the solution, the salt concentration, and the grafting density. Results are compared to experimental and theoretical works from the literature using coarse-grained representations of poly(acrylic acid) (PAA) and poly(2-vinyl pyridine) (P2VP) polymer-based brushes. As the Born self-energy of ions can be straightforwardly included in the numerical approach, we also study its effect on the local charge regulation mechanism of the brush. We find that its effect becomes significant when the brush is dense and exposed to high salt concentrations. The numerical methodology is then applied (1) to the study of the kinetics of collapse/swelling of a P2VP brush and (2) to the ability of an applied voltage to induce collapse/swelling of a PAA brush in a pH range close to the pKa value of the polymer.
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Affiliation(s)
- F Léonforte
- Institut für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - U Welling
- Institut für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - M Müller
- Institut für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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12
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Response of bi-disperse polyelectrolyte brushes to external electric fields — A numerical self-consistent field theory study. CHINESE JOURNAL OF POLYMER SCIENCE 2016. [DOI: 10.1007/s10118-017-1868-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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Léonforte F, Müller M. Functional Poly(N-isopropylacrylamide)/Poly(acrylic acid) Mixed Brushes for Controlled Manipulation of Nanoparticles. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00535] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Fabien Léonforte
- Institut
für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marcus Müller
- Institut
für Theoretische Physik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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14
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Raup A, Stahlschmidt U, Jérôme V, Synatschke CV, Müller AHE, Freitag R. Influence of Polyplex Formation on the Performance of Star-Shaped Polycationic Transfection Agents for Mammalian Cells. Polymers (Basel) 2016; 8:polym8060224. [PMID: 30979314 PMCID: PMC6432395 DOI: 10.3390/polym8060224] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/30/2016] [Accepted: 06/01/2016] [Indexed: 12/19/2022] Open
Abstract
Genetic modification (“transfection”) of mammalian cells using non-viral, synthetic agents such as polycations, is still a challenge. Polyplex formation between the DNA and the polycation is a decisive step in such experiments. Star-shaped polycations have been proposed as superior transfection agents, yet have never before been compared side-by-side, e.g., in view of structural effects. Herein four star-shaped polycationic structures, all based on (2-dimethylamino) ethyl methacrylate (DMAEMA) building blocks, were investigated for their potential to deliver DNA to adherent (CHO, L929, HEK-293) and non-adherent (Jurkat, primary human T lymphocytes) mammalian cells. The investigated vectors included three structures where the PDMAEMA arms (different arm length and grafting densities) had been grown from a center silsesquioxane or silica-coated γ-Fe2O3-core and one micellar structure self-assembled from poly(1,2-butadiene)-block PDMAEMA polymers. All nano-stars combined high transfection potential with excellent biocompatibility. The micelles slightly outperformed the covalently linked agents. For method development and optimization, the absolute amount of polycation added to the cells was more important than the N/P-ratio (ratio between polycation nitrogen and DNA phosphate), provided a lower limit was passed and enough polycation was present to overcompensate the negative charge of the plasmid DNA. Finally, the matrix (NaCl vs. HEPES-buffered glucose solution), but also the concentrations adjusted during polyplex formation, affected the results.
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Affiliation(s)
- Alexander Raup
- Process Biotechnology, University of Bayreuth, 95440 Bayreuth, Germany.
| | | | - Valérie Jérôme
- Process Biotechnology, University of Bayreuth, 95440 Bayreuth, Germany.
| | - Christopher V Synatschke
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, 60611 IL, USA.
| | - Axel H E Müller
- Institute of Organic Chemistry, Johannes-Gutenberg-University, 55099 Mainz, Germany.
| | - Ruth Freitag
- Process Biotechnology, University of Bayreuth, 95440 Bayreuth, Germany.
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15
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Mahalik JP, Yang Y, Deodhar C, Ankner JF, Lokitz BS, Kilbey SM, Sumpter BG, Kumar R. Monomer volume fraction profiles in pH responsive planar polyelectrolyte brushes. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- J. P. Mahalik
- Computer Science and Mathematics Division; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - Yubo Yang
- Denison University; Granville Ohio 43023
| | - Chaitra Deodhar
- Department of Chemistry; University of Tennessee; Knoxville Tennessee 37996
| | - John F. Ankner
- Spallation Neutron Source; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - Bradley S. Lokitz
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - S. Michael Kilbey
- Department of Chemistry; University of Tennessee; Knoxville Tennessee 37996
| | - Bobby G. Sumpter
- Computer Science and Mathematics Division; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - Rajeev Kumar
- Computer Science and Mathematics Division; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
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16
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Chen G, Das S. Scaling Laws and Ionic Current Inversion in Polyelectrolyte-Grafted Nanochannels. J Phys Chem B 2015; 119:12714-26. [DOI: 10.1021/acs.jpcb.5b07167] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Guang Chen
- Department of Mechanical
Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical
Engineering, University of Maryland, College Park, Maryland 20742, United States
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17
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Tong C. Numerical self-consistent field theory study of the response of strong polyelectrolyte brushes to external electric fields. J Chem Phys 2015; 143:054903. [DOI: 10.1063/1.4927814] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Chaohui Tong
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
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18
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Lei Z, Miao B, Yang S, Chen EQ. Curvature elasticity of a grafted polyelectrolyte brush. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:062602. [PMID: 26172729 DOI: 10.1103/physreve.91.062602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Indexed: 06/04/2023]
Abstract
The curvature elasticity of a polyelectrolyte brush monolayer attached to curved surface is investigated theoretically. An analytical method based on the strong-stretching theory for a Gaussian chain is developed to calculate the elastic modulus induced by a polyelectrolyte brush. In particular, the scaling relations for the bending or Gaussian modulus with respect to system parameters related to the electrostatic interaction (degree of ionization and salt concentration) are derived. Using the numerical self-consistent-field theory, the inner structural, free-energy, and elastic moduli are computed for the polyelectrolyte brush with excluded-volume interactions. Compared to the analytical result, the curvature elasticity has a weaker dependence on the system parameters, which is attributed to the linearization for the Poisson-Boltzmann equation in the analytical treatment. Furthermore, our results are compared to the curvature elasticity of a bare charged surface, wherefrom the unique polyelectrolyte brush effect on the surface elasticity is clarified clearly. The scaling relations derived in our paper can serve as a guide to experimental studies on the related systems.
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Affiliation(s)
- Zhen Lei
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Bing Miao
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuang Yang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Er-Qiang Chen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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19
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Willott JD, Murdoch TJ, Humphreys BA, Edmondson S, Wanless EJ, Webber GB. Anion-specific effects on the behavior of pH-sensitive polybasic brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3707-3717. [PMID: 25768282 DOI: 10.1021/acs.langmuir.5b00116] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The anion-specific solvation and conformational behavior of weakly basic poly(2-dimethylamino)ethyl methacrylate (poly(DMA)), poly(2-diethylamino)ethyl methacrylate (poly(DEA)), and poly(2-diisopropylamino)ethyl methacrylate (poly(DPA)) brushes, with correspondingly increasing inherent hydrophobicity, have been investigated using in situ ellipsometric and quartz crystal microbalance with dissipation (QCM-D) measurements. In the osmotic brush regime, as the initial low concentration of salt is increased, the brushes osmotically swell by the uptake of solvent as they become charged and the attractive hydrophobic inter- and intrachain interactions are overcome. With increased ionic strength, the brushes move into the salted brush regime where they desolvate and collapse as their electrostatic charge is screened. Here, as the brushes collapse, they transition to more uniform and rigid conformations, which dissipate less energy, than similarly solvated brushes at lower ionic strength. Significantly, in these distinct regimes brush behavior is not only ionic strength dependent but is also influenced by the nature of the added salt based on its position in the well-known Hofmeister or lyotropic series, with potassium acetate, nitrate, and thiocyanate investigated. The strongly kosmotropic acetate anions display low affinity for the hydrophobic polymers, and largely unscreened electrosteric repulsions allow the brushes to remain highly solvated at higher acetate concentrations. The mildly chaotropic nitrate and strongly chaotropic thiocyanate anions exhibit a polymer hydrophobicity-dependent affinity for the brushes. Increasing thiocyanate concentration causes the brushes to collapse at lower ionic strength than for the other two anions. This study of weak polybasic brushes demonstrates the importance of all ion, solvent, and polymer interactions.
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Affiliation(s)
- Joshua D Willott
- †Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Timothy J Murdoch
- †Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Ben A Humphreys
- †Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Steve Edmondson
- ‡School of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Erica J Wanless
- †Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B Webber
- †Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
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20
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Tong C. Numerical study of weak polybase brushes grafted on neutral or charged spherical surface by the self-consistent field theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:15301-15308. [PMID: 25459349 DOI: 10.1021/la503526a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The self-consistent field theory (SCFT) is employed to numerically study the response of weak polybase type polymer chains grafted on a sphere to electric fields generated by the uniform positive or negative charges on the grafting substrate in the planar polyelectrolyte brush limit. Also the effect of curvature of the grafting sphere on the brush height of weak polybase brushes in the absence of surface charges is investigated. The numerical study reveals interesting and nontrivial dependence of the brush height on the radius of the grafting substrate. Consistent with experimental results, in the parameter range of the surface charge density examined, the brush height is found to be independent of the applied electric field at intermediate and high grafting densities. At relatively low grafting density, the applied negative surface charge which is termed as negative bias in this study results in a reduction of the brush height. At rather low grafting density, the positive bias corresponding to applied positive surface charges can lead to a slight increase in the brush height. The underlining mechanism governing the response of weak polybase brushes to the applied electric field is elucidated.
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Affiliation(s)
- Chaohui Tong
- Department of Physics, Ningbo University , Ningbo 315211, China
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21
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Quan G, Wang M, Tong C. A numerical study of spherical polyelectrolyte brushes by the self-consistent field theory. POLYMER 2014. [DOI: 10.1016/j.polymer.2014.10.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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22
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Liu S, Huang W, Jin MJ, Wang QM, Zhang GL, Wang XM, Shao S, Gao ZG. High gene delivery efficiency of alkylated low-molecular-weight polyethylenimine through gemini surfactant-like effect. Int J Nanomedicine 2014; 9:3567-81. [PMID: 25114526 PMCID: PMC4122513 DOI: 10.2147/ijn.s64554] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To our knowledge, the mechanism underlying the high transfection efficiency of alkylated low-molecular-weight polyethylenimine (PEI) is not yet well understood. In this work, we grafted branched PEI (molecular weight of 1,800 Da; bPEI1800) with lauryl chains (C12), and found that bPEI1800-C12 was structurally similar to gemini surfactant and could similarly assemble into micelle-like particles. Stability, cellular uptake, and lysosome escape ability of bPEI1800-C12/DNA polyplexes were all greatly enhanced after C12 grafting. bPEI1800-C12/DNA polyplexes exhibited significantly higher transfection efficiency than Lipofectamine™ 2000 in the presence of serum. Bioluminescence imaging showed that systemic injection of bPEI1800-C12/DNA polyplexes resulted in intensive luciferase expression in vivo and bioluminescence signals that could be detected even in the head. Altogether, the high transfection efficacy of bPEI1800-C12 was because bPEI1800-C12, being an analog of gemini surfactant, facilitated lysosome escape and induced the coil–globule transition of DNA to assemble into a highly organized micelle-like structure that showed high stability.
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Affiliation(s)
- Shan Liu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China ; Department of Pharmaceutics, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Wei Huang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China ; Department of Pharmaceutics, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Ming-Ji Jin
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China ; Department of Pharmaceutics, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Qi-Ming Wang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China ; Department of Pharmaceutics, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Gan-Lin Zhang
- Beijing Hospital of Traditional Chinese Medicine affiliated to Capital Medical University, Beijing, People's Republic of China
| | - Xiao-Min Wang
- Beijing Hospital of Traditional Chinese Medicine affiliated to Capital Medical University, Beijing, People's Republic of China
| | - Shuai Shao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China ; Department of Pharmaceutics, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Zhong-Gao Gao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China ; Department of Pharmaceutics, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
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23
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Lee H, Tsouris V, Lim Y, Mustafa R, Choi J, Choi YH, Park HW, Meron M, Lin B, Won YY. Macroscopic lateral heterogeneity observed in a laterally mobile immiscible mixed polyelectrolyte-neutral polymer brush. SOFT MATTER 2014; 10:3771-82. [PMID: 24695635 PMCID: PMC4397986 DOI: 10.1039/c4sm00022f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We studied mixed poly(ethylene oxide) (PEO) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes. The question we attempted to answer was: when the chain grafting points are laterally mobile, how will this lateral mobility influence the structure and phase behavior of the mixed brush? Three different model mixed PEO/PDMAEMA brush systems were prepared: (1) a laterally mobile mixed brush by spreading onto the air-water interface a mixture of poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) and poly(2-(dimethylamino)ethyl methacrylate)-poly(n-butyl acrylate) (PDMAEMA-PnBA) diblock copolymers (the specific diblock copolymers used will be denoted as PEO113-PnBA100 and PDMAEMA118-PnBA100, where the subscripts refer to the number-average degrees of polymerization of the individual blocks), (2) a mobility-restricted (inseparable) version of the above mixed brush prepared using a PEO-PnBA-PDMAEMA triblock copolymer (denoted as PEO113-PnBA89-PDMAEMA120) having respective brush molecular weights matched with those of the diblock copolymers, and (3) a different laterally mobile mixed PEO and PDMAEMA brush prepared from a PEO113-PnBA100 and PDMAEMA200-PnBA103 diblock copolymer combination, which represents a further more height-mismatched mixed brush situation than described in (1). These three mixed brush systems were investigated by surface pressure-area isotherm and X-ray (XR) reflectivity measurements. These experimental data were analyzed within the theoretical framework of a continuum self-consistent field (SCF) polymer brush model. The combined experimental and theoretical results suggest that the mobile mixed brush derived using the PEO113-PnBA100 and PDMAEMA118-PnBA100 combination (i.e., mixed brush System #1) undergoes a lateral macroscopic phase separation at high chain grafting densities, whereas the more height-mismatched system (System #3) is only microscopically phase separated under comparable brush density conditions even though the lateral mobility of the grafted chains is unrestricted. The macroscopic phase separation observed in the laterally mobile mixed brush system is in contrast with the microphase separation behavior commonly observed in two-dimensional laterally mobile charged small molecule mixtures. Further study is needed to determine the detailed morphologies of the macro- and microphase-separated mixed PEO/PDMAEMA brushes.
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Affiliation(s)
- Hoyoung Lee
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
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24
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Alswieleh A, Cheng N, Leggett GJ, Armes SP. Spatial control over cross-linking dictates the pH-responsive behavior of poly(2-(tert-butylamino)ethyl methacrylate) brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1391-400. [PMID: 24417283 PMCID: PMC4190050 DOI: 10.1021/la403666y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 01/13/2014] [Indexed: 05/12/2023]
Abstract
Surface-initiated atom transfer radical polymerization (ATRP) of 2-(tert-butylamino)ethyl methacrylate (TBAEMA) produced pH-responsive secondary amine-functionalized polymer brushes with dry thicknesses ranging from 4 to 28 nm, as determined by ellipsometry. At low pH, linear PTBAEMA brushes became protonated and highly swollen; brush collapse occurred when the solution pH was increased to ca. 7.7 due to deprotonation. PTBAEMA brushes were subsequently cross-linked using tolylene-2,4-diisocyanate-terminated poly(propylene glycol) (PPG-TGI) in either THF (a good solvent for PTBAEMA) or n-hexane (a poor solvent). The intensity of the C-C-O component (286.5 eV) in the C1s X-ray photoelectron spectrum increased after reaction with PPG-TDI, suggesting that cross-linking was successful in both solvents. Ellipsometry studies indicated that the pH-responsive behavior of these cross-linked brushes is dictated by the spatial location of the PPG-TDI cross-linker. Thus, uniformly cross-linked brushes prepared in THF became appreciably less swollen at a given (low) pH than surface-cross-linked brushes prepared in n-hexane. Micro- and nanopatterned PTBAEMA brushes were prepared via UV irradiation and interference lithography, respectively, and characterized by atomic force microscopy. The change in brush height was determined as a function of pH, and these AFM observations correlated closely with the ellipsometric studies.
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Affiliation(s)
| | | | - Graham J. Leggett
- Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, United Kingdom
| | - Steven P. Armes
- Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, United Kingdom
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25
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Wang M, Tong C. A numerical study of two opposing polyelectrolyte brushes by the self-consistent field theory. RSC Adv 2014. [DOI: 10.1039/c4ra01935k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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26
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Tong C. The numerical study of the adsorption of flexible polyelectrolytes with the annealed charge distribution onto an oppositely charged sphere by the self-consistent field theory. J Chem Phys 2013; 139:084903. [DOI: 10.1063/1.4819037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [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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Lewis T, Ganesan V. Interactions between Grafted Cationic Dendrimers and Anionic Bilayer Membranes. J Phys Chem B 2013; 117:9806-20. [DOI: 10.1021/jp4053049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Thomas Lewis
- Department
of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Venkat Ganesan
- Department of Chemical Engineering and Institute for
Computational and Engineering Sciences, University of Texas at Austin, Austin, Texas 78712, United States
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28
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Won YY, Lee H. "pH phoresis": a new concept that can be used for improving drug delivery to tumor cells. J Control Release 2013; 170:396-400. [PMID: 23791576 DOI: 10.1016/j.jconrel.2013.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/04/2013] [Accepted: 06/08/2013] [Indexed: 11/27/2022]
Abstract
We propose a new concept describing how nanoparticles composed of weak polybases (such as polyamines) would behave when they are exposed to a pH gradient; weak polybase-containing particles will tend to accumulate preferentially in low pH regions under a pH gradient environment. This phenomenon, which we term "pH phoresis", may provide a useful mechanism for improving the delivery of drugs to cancer cells in solid tumor tissues.
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Affiliation(s)
- You-Yeon Won
- School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA.
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29
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Deodhar C, Soto-Cantu E, Uhrig D, Bonnesen P, Lokitz BS, Ankner JF, Kilbey SM. Hydration in Weak Polyelectrolyte Brushes. ACS Macro Lett 2013; 2:398-402. [PMID: 35581845 DOI: 10.1021/mz300615v] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Weak polyelectrolytes (PEs) are complex because intertwined connections between conformation and charge are regulated by the local dielectric environment. While end-tethered PE chains-so-called PE "brushes"-are archetypal systems for comprehending structure-property relationships, it is revealed that the reference state nominally referred to as "dry" is, in fact, a situation in which the chains are hydrated by water vapor in the ambient. Using charge-negative PE homopolymer brushes based on methacrylic acid and copolymer brushes that incorporate methacrylic acid and 2-hydroxyethylmethacrylate, we determine self-consistently the water content of PE films using neutron reflectometry under different hydration conditions. Modeling multiple data sets, we obtain dry polymer mass density and layer thickness, independent of adsorbed water, and PE brush profiles into different pH solutions. We show that hydration of the chains distorts, here by as much as 30%, the quantification of these important physical parameters benchmarked to films in ambient conditions.
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Affiliation(s)
- Chaitra Deodhar
- Department
of Chemistry, University of Tennessee,
Knoxville, Tennessee 37996,
United States
| | - Erick Soto-Cantu
- Department
of Chemistry, University of Tennessee,
Knoxville, Tennessee 37996,
United States
| | | | | | | | | | - S. Michael Kilbey
- Department
of Chemistry, University of Tennessee,
Knoxville, Tennessee 37996,
United States
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30
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Barr SA, Panagiotopoulos AZ. Conformational transitions of weak polyacids grafted to nanoparticles. J Chem Phys 2012; 137:144704. [PMID: 23061858 DOI: 10.1063/1.4757284] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The charge distribution on polyelectrolytes is a key factor, which controls their conformation and interactions. In weak polyelectrolytes, this distribution is determined by a number of factors, including the solvent conditions and local environment. In this work, we investigate charge distributions of chains end-grafted on a spherical nanoparticle in a salt solution, using grand canonical titration Monte Carlo simulations of a coarse-grained polymer model. In this approach, the ionization state of each polymer bead fluctuates based on the dissociation constant, pH of the solution, and interactions with other particles in the system. We determine charge and polymer conformations as functions of the pH and solvent quality. We compare the results to a fixed charge model and also investigate the role of grafting density and the effect of curvature on the film morphologies.
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Affiliation(s)
- S A Barr
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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31
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Kumar R, Sumpter BG, Kilbey SM. Charge regulation and local dielectric function in planar polyelectrolyte brushes. J Chem Phys 2012; 136:234901. [DOI: 10.1063/1.4729158] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Lee H, Kim DH, Witte KN, Ohn K, Choi J, Akgun B, Satija S, Won YY. Water Is a Poor Solvent for Densely Grafted Poly(ethylene oxide) Chains: A Conclusion Drawn from a Self-Consistent Field Theory-Based Analysis of Neutron Reflectivity and Surface Pressure–Area Isotherm Data. J Phys Chem B 2012; 116:7367-78. [PMID: 22616550 DOI: 10.1021/jp301817e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Hoyoung Lee
- School of Chemical
Engineering, Purdue University, West Lafayette, Indiana, United States
| | - Dae Hwan Kim
- School of Chemical
Engineering, Purdue University, West Lafayette, Indiana, United States
| | - Kevin N. Witte
- School of Chemical
Engineering, Purdue University, West Lafayette, Indiana, United States
| | - Kimberly Ohn
- School of Chemical
Engineering, Purdue University, West Lafayette, Indiana, United States
| | - Je Choi
- School of Chemical
Engineering, Purdue University, West Lafayette, Indiana, United States
| | - Bulent Akgun
- NIST Center for Neutron Research
(NCNR), National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, United States
- Department of Materials
Science and Engineering, University of Maryland, College Park, Maryland, United States
| | - Sushil Satija
- NIST Center for Neutron Research
(NCNR), National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, United States
| | - You-Yeon Won
- School of Chemical
Engineering, Purdue University, West Lafayette, Indiana, United States
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33
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Matsen MW. Effect of salt on the compression of polyelectrolyte brushes in a theta solvent. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:13. [PMID: 22367602 DOI: 10.1140/epje/i2012-12013-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 02/05/2012] [Accepted: 02/07/2012] [Indexed: 05/31/2023]
Abstract
Classical strong-stretching theory (SST) predicts that, as opposing polyelectrolyte brushes are compressed together in a salt-free theta solvent, they contract so as to maintain a finite polymer-free gap, which offers a potential explanation for the ultra-low frictional forces observed in experiments despite the application of large normal forces. However, the SST ignores chain fluctuations, which would tend to close the gap resulting in physical contact and in turn significant friction. In a preceding study, we examined the effect of fluctuations using self-consistent field theory (SCFT) and illustrated that high normal forces can still be applied before the gap is destroyed. We now look at the effect of adding salt. It is found to reduce the long-range interaction between the brushes but has little effect on the short-range part, provided the concentration does not enter the salted-brush regime. Consequently, the maximum normal force between two planar brushes at the point of contact is remarkably unaffected by salt. For the crossed-cylinder geometry commonly used in experiments, however, there is a gradual reduction because in this case the long-range part of the interaction contributes to the maximum normal force.
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Affiliation(s)
- M W Matsen
- University of Reading, School of Mathematical and Physical Sciences, Whiteknights, Reading, UK.
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34
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Qu LJ, Man X, Han CC, Qiu D, Yan D. Responsive Behaviors of Diblock Polyampholyte Brushes within Self-Consistent Field Theory. J Phys Chem B 2012; 116:743-50. [DOI: 10.1021/jp210165t] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Li-Jian Qu
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xingkun Man
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Charles C. Han
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Dong Qiu
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Dadong Yan
- Department of Physics, Beijing Normal University, Beijing 100875
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35
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Jia H, Wildes A, Titmuss S. Structure of pH-Responsive Polymer Brushes Grown at the Gold–Water Interface: Dependence on Grafting Density and Temperature. Macromolecules 2011. [DOI: 10.1021/ma201839y] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Haidong Jia
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, U.K
| | - Andrew Wildes
- Institut Laue-Langevin, BP 156, 38402 Grenoble Cedex 9, France
| | - Simon Titmuss
- School of Physics & Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, U.K
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36
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Lewis T, Pryamitsyn V, Ganesan V. Mean field theory of charged dendrimer molecules. J Chem Phys 2011; 135:204902. [DOI: 10.1063/1.3663382] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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37
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Borozenko O, Godin R, Lau KL, Mah W, Cosa G, Skene WG, Giasson S. Monitoring in Real-Time the Degrafting of Covalently Attached Fluorescent Polymer Brushes Grafted to Silica Substrates—Effects of pH and Salt. Macromolecules 2011. [DOI: 10.1021/ma2013755] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Olga Borozenko
- Department of Chemistry Université de Montréal, C.P. 6128, succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Robert Godin
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada, H3A 2K6
| | - Kai Lin Lau
- Department of Chemistry Université de Montréal, C.P. 6128, succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada, H3A 2K6
| | - Wayne Mah
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada, H3A 2K6
| | - Gonzalo Cosa
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada, H3A 2K6
| | - W. G. Skene
- Department of Chemistry Université de Montréal, C.P. 6128, succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Suzanne Giasson
- Department of Chemistry Université de Montréal, C.P. 6128, succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
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Zhulina EB, Borisov OV. Poisson-Boltzmann theory of pH-sensitive (annealing) polyelectrolyte brush. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:10615-10633. [PMID: 21823583 DOI: 10.1021/la201456a] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a self-consistent field analytical theory of a polymer brush formed by weakly charged pH-sensitive (annealing) polyelectrolytes tethered to a solid-liquid interface and immersed in buffer solution of low molecular weight salt. We use the Poisson-Boltzmann framework, applied by us previously to polyelectrolyte (PE) brushes with quenched charge (Zhulina, E. B.; Borisov, O. V. J. Chem. Phys. 1997, 107, 5952). This approach allows for detailed analysis of the internal structure of annealing PE brush in terms of polymer density distribution, profiles of electrostatic potential and of local degree of chain ionization as a function of buffer ionic strength and pH without any assumptions on mobile ion distribution imposed in earlier scaling-type models. The presented analytical theory recovers all major asymptotic dependences for average brush properties predicted earlier. In particular, a nonmonotonic dependence of brush thickness on ionic strength and grafting density is confirmed and specified with accuracy of numerical coefficients including crossover regions. Moreover, the theory predicts qualitatively new effects, such as, e.g., disproportionation of tethered polyions into weakly charged concentrated proximal and strongly charged sparse distal brush domains at low salt and moderate grating densities. The presented results allow us to quantify responsive features of annealing PE brushes whose large-scale and local conformational properties can be manipulated by external stimuli.
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Affiliation(s)
- E B Zhulina
- Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg 199004, Russia
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39
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Matsen MW. Compression of polyelectrolyte brushes in a salt-free theta solvent. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:45. [PMID: 21562969 DOI: 10.1140/epje/i2011-11045-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 04/12/2011] [Indexed: 05/30/2023]
Abstract
This paper examines the normal force between two opposing polyelectrolyte brushes and the interpenetration of their chains that is responsible for sliding friction. It focuses on the special case of semi-dilute brushes in a salt-free theta solvent, for which Zhulina and Borisov (J. Chem. Phys. 107, 5952 (1997)) have derived analytical predictions using the classical strong-stretching theory (SST). Interestingly, SST predicts that the brushes contract as they are compressed together maintaining a polymer-free gap, which provides an explanation for the ultra-low frictional forces observed in experiment. We examine the degree to which the SST predictions are affected by chain fluctuations by employing self-consistent field theory (SCFT). While the normal force is relatively unaffected, fluctuations are found to have a strong impact on brush interpenetration. Even still, the contraction of the brushes does significantly prolong the onset of interpenetration, implying that a sizeable normal force can be achieved before the sliding friction becomes significant.
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Affiliation(s)
- M W Matsen
- School of Mathematical and Physical Sciences, University of Reading, Whiteknights, Reading, UK.
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Lee H, Son SH, Sharma R, Won YY. A Discussion of the pH-Dependent Protonation Behaviors of Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and Poly(ethylenimine-ran-2-ethyl-2-oxazoline) (P(EI-r-EOz)). J Phys Chem B 2011; 115:844-60. [PMID: 21210675 DOI: 10.1021/jp109151s] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Hoyoung Lee
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Sang Ha Son
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Rahul Sharma
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - You-Yeon Won
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
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41
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Moglianetti M, Webster JRP, Edmondson S, Armes SP, Titmuss S. Neutron reflectivity study of the structure of pH-responsive polymer brushes grown from a macroinitiator at the sapphire-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:12684-12689. [PMID: 20583764 DOI: 10.1021/la101550w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes have been grown by surface-initiated atom transfer radical polymerization (SI-ATRP) from a polyanionic macroinitiator adsorbed at the sapphire-water interface, and neutron reflectivity has been used to characterize the structures and pH response of the brushes. The polymer brushes are well-described by Gaussian density profiles with an additional thin, dense layer close to the solid-liquid interface for the thicker brushes at pH 7 and 9, which produces a spike in the density profile. The spike in the distribution accounts for less than 5% of the polymer and disappears as the brushes swell at pH 3. The observed swelling behavior has been used in combination with the predictions of scaling theory and previous experimental measurements to determine the grafted density of PDMAEMA chains.
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Affiliation(s)
- Mauro Moglianetti
- Department of Chemistry, Physical & Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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Lego B, Skene WG, Giasson S. Swelling Study of Responsive Polyelectrolyte Brushes Grafted from Mica Substrates: Effect of pH, Salt, and Grafting Density. Macromolecules 2010. [DOI: 10.1021/ma902588j] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Suzanne Giasson
- Department of Chemistry
- Faculty of Pharmacy, Centre for Self-Assembled Chemical Structures
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Hur J, Witte KN, Sun W, Won YY. On the origins of the salt-concentration-dependent instability and lateral nanoscale heterogeneities of weak polyelectrolyte brushes: gradient brush experiment and Flory-type theoretical analysis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:2021-2034. [PMID: 20099924 DOI: 10.1021/la902549b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigated, by experiment and theory, the lateral structure of a weak polyelectrolyte brush at various added salt concentrations and chain grafting densities. Model poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes with grafting density gradients were developed for this study by using a novel "Langmuir-Blodgett-deposition-under-compression" (LB\C) method. Fluid AFM images of these brushes indicate that the lateral structure of the brush system is sensitive to both added salt concentration and grafting density. Under low salt conditions, 0-20 mM NaCl, the brush structure shows strong microscopic lateral heterogeneities at high grafting densities; both the width and height of the heterogeneities increase with increasing grafting density but are independent of the salt concentration. As the bulk salt concentration is increased to an intermediate regime, 60-100 mM NaCl, these heterogeneities become smaller in size and number, coexisting with smooth homogeneous regions. At high enough concentrations, 300-500 mM NaCl, the entire surface becomes homogeneous. A simple free energy-based Flory-type argument is presented which explains the essential features of the thermodynamic behavior of the brush system. In the zero-salt limit, relatively few monomers are charged, and the hydrophobicity of the backbone chain drives the collapse/aggregation of the chains. At high salt concentrations, the brush chains become sufficiently charged to overcome the hydrophobic nature of the monomers and stabilize the homogeneous state. However, at intermediate salt concentrations, it is found that the osmotic pressure of the counterions surrounding the charged polymer moieties can be decreased by collapsing the chain structure while simultaneously decreasing the number of charges along the backbone and releasing small ions into the bulk solution. This effect, which we term "osmotic instability", serves to destabilize the homogeneous brush configuration.
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Affiliation(s)
- Jaehyun Hur
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA
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Won YY, Sharma R, Konieczny SF. Missing pieces in understanding the intracellular trafficking of polycation/DNA complexes. J Control Release 2009; 139:88-93. [PMID: 19580830 DOI: 10.1016/j.jconrel.2009.06.031] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- You-Yeon Won
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
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