1
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Tangso KJ, Patel H, Lindberg S, Hartley PG, Knott R, Spicer PT, Boyd BJ. Controlling the Mesostructure Formation within the Shell of Novel Cubic/Hexagonal Phase Cetyltrimethylammonium Bromide-Poly(acrylamide-acrylic acid) Capsules for pH Stimulated Release. ACS APPLIED MATERIALS & INTERFACES 2015; 7:24501-24509. [PMID: 26457761 DOI: 10.1021/acsami.5b05821] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The self-assembly of ordered structures in mixtures of oppositely charged surfactant and polymer systems has been exploited in various cleaning and pharmaceutical applications and continue to attract much interest since their discovery in the late twentieth century. The ability to control the electrostatic and hydrophobic interactions that dictate the formation of liquid crystalline phases in these systems is advantageous in manipulation of structure and rendering them responsive to external stimuli. Nanostructured capsules comprised of the cationic surfactant, cetyltrimethylammonium bromide (CTAB), and the diblock copolymer poly(acrylamide-acrylic acid) (PAAm-AA) were prepared to assess their potential as pH responsive nanomaterials. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified coexisting Pm3n cubic and hexagonal phases at the surfactant-polymer interface. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and solution pH, respectively, and were found to influence the liquid crystalline nanostructure formed. The lattice parameter of the mesophases and the fraction of cubic phase in the system decreased upon heating. Acidic conditions resulted in the loss of the highly ordered structures due to protonation of the carboxylic acid group, and subsequent reduction of attractive forces previously present between the oppositely charged molecules. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from nanostructured macro-sized capsules significantly increased when the pH of the solution was adjusted from pH 7 to pH 2. This allowed for immediate release of the compound of interest "on demand", opening new options for structured materials with increased functionality over typical layer-by-layer capsules.
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Affiliation(s)
- Kristian J Tangso
- Drug Delivery, Disposition and Dynamics and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus) , 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Hetika Patel
- School of Pharmacy, University College London , 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - Seth Lindberg
- The Procter and Gamble Company , Corporate Engineering Technical Laboratories Building, Cincinnati, Ohio 45069, United States
| | - Patrick G Hartley
- Commonwealth Scientific and Industrial Research Organization , Bag 10, Clayton South, Victoria 3169, Australia
| | - Robert Knott
- Bragg Institute, Australian Nuclear Science and Technology Organization , Menai, New South Wales 2234, Australia
| | - Patrick T Spicer
- School of Chemical Engineering, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Ben J Boyd
- Drug Delivery, Disposition and Dynamics and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus) , 381 Royal Parade, Parkville, Victoria 3052, Australia
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2
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Agzenai Y, Pacios IE, Renamayor CS. Effect of water soluble molecules on the stability and flexibility of lyotropic lamellar structures. Polymer molecular weight influence. Eur Polym J 2015. [DOI: 10.1016/j.eurpolymj.2015.06.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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3
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Schindler M, Koller M, Müller-Buschbaum P. Pressure-Sensitive Adhesives under the Influence of Relative Humidity: Inner Structure and Failure Mechanisms. ACS APPLIED MATERIALS & INTERFACES 2015; 7:12319-12327. [PMID: 25396744 DOI: 10.1021/am506265e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Model pressure-sensitive adhesive (PSA) films of the statistical copolymer P(EHA-stat-20MMA), which comprises 80% ethylhexyl acrylate (EHA) and 20% methyl methacrylate (MMA), are studied. The PSA films are stored under different relative humidities from <2% to 96% for 24 h and subsequently investigated concerning the near-surface composition profile by measuring X-ray reflectivity (XRR) and tack performance. For both types of measurements, special custom-made sample environments are used, which ensure constant temperature and relative humidity during the XRR and tack measurements. Different failure mechanisms of the adhesive bond are found by adjusting the relative humidity. XRR measurements evidence enrichment layers in vicinity to and at the surface depending on the provided relative humidity during the postproduction treatment, which also influence the tack performance. This finding is supported by tack measurements using punches with different roughness.
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Affiliation(s)
- Markus Schindler
- Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Manuel Koller
- Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
| | - Peter Müller-Buschbaum
- Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-Franck-Strasse 1, 85748 Garching, Germany
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4
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Tangso KJ, Lindberg S, Hartley PG, Knott R, Spicer P, Boyd BJ. Formation of liquid-crystalline structures in the bile salt-chitosan system and triggered release from lamellar phase bile salt-chitosan capsules. ACS APPLIED MATERIALS & INTERFACES 2014; 6:12363-12371. [PMID: 25050454 DOI: 10.1021/am502192t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Nanostructured capsules comprised of the anionic bile salt, sodium taurodeoxycholate (STDC), and the biocompatible cationic polymer, chitosan, were prepared to assess their potential as novel tailored release nanomaterials. For comparison, a previously studied system, sodium dodecyl sulfate (SDS), and polydiallyldimethylammonium chloride (polyDADMAC) was also investigated. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified the presence of lamellar and hexagonal phase at the surfactant-polymer interface of the respective systems. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and salt concentration, respectively, and were found to influence the liquid-crystalline nanostructure formed. The hexagonal phase persisted at high temperatures, however the lamellar phase structure was lost above ca. 45 °C. Both mesophases were found to dissociate upon addition of 4% NaCl solution. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from the lamellar phase significantly increased in response to changes in the solution conditions studied, suggesting that modulating the drug release from these bile salt-chitosan capsules is readily achieved. In contrast, release from the hexagonal phase capsules had no appreciable response to the stimuli applied. These findings provide a platform for these oppositely charged surfactant and polymer systems to function as stimuli-responsive or sustained-release drug delivery systems.
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Affiliation(s)
- Kristian J Tangso
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus) , 381 Royal Parade, Parkville, Victoria 3052, Australia
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5
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Bitton R, Chow LW, Zha RH, Velichko YS, Pashuck ET, Stupp SI. Electrostatic control of structure in self-assembled membranes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:500-505. [PMID: 24022896 PMCID: PMC4096135 DOI: 10.1002/smll.201300254] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 07/09/2013] [Indexed: 06/02/2023]
Abstract
Self-assembling peptide amphiphiles (PAs) can form hierarchically ordered membranes when brought in contact with aqueous polyelectrolytes of the opposite charge by rapidly creating a diffusion barrier composed of filamentous nanostructures parallel to the plane of the incipient membrane. Following this event, osmotic forces and charge complexation template nanofiber growth perpendicular to the plane of the membrane in a dynamic self-assembly process. In this work, we show that this hierarchical structure requires massive interfacial aggregation of PA molecules, suggesting the importance of rapid diffusion barrier formation. Strong PA aggregation is induced here through the use of heparin-binding PAs with heparin and also with polyelectrolytes of varying charge density. Small angle X-ray scattering shows that in the case of weak PA-polyelectrolyte interaction, membranes formed display a cubic phase ordering on the nanoscale that likely results from clusters of PA nanostructures surrounded by polyelectrolyte chains.
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Affiliation(s)
| | | | - R. Helen Zha
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, United States
| | - Yuri S. Velichko
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, United States
| | - E. Thomas Pashuck
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, United States
| | - Samuel I. Stupp
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States; Department of Chemistry, Northwestern University, Evanston, IL 60208, United States; Department of Medicine, Northwestern University, Chicago, IL, 60611, United States; Institute for BioNanotechnology in Medicine, Northwestern University, Chicago, IL, 60611, United States
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6
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Agzenai Y, Pacios IE, Renamayor CS. Copolymer-surfactant complexes obtained in a lamellar lyotropic medium. J Phys Chem B 2013; 117:3019-27. [PMID: 23387994 DOI: 10.1021/jp310238y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polymer-surfactant complexes formed between charged copolymers and oppositely charged surfactants are analyzed as a function of the charge density in the macromolecule. Copolymers of ionizable diallyldimethylammonium chloride (DADMAC) and neutral acrylamide are obtained at different comonomer ratios. When mixed with the lamellar medium formed by the anionic surfactant 1,4-bis(2-ethylhexyl)sodium sulfosuccinate (AOT) in water, they give rise to highly condensed lamellar phases in equilibrium with another lyotropic phase. The structure of these phases is studied by SAXS and optical microscopy revealing the formation of copolymer-surfactant complexes which present a lamellar structure. The composition of the phases is inaccessible to direct determination, because they do not separate macroscopically (in most of the samples). Thus, the stoichiometry is determined using a model which considers the charge density of the copolymers. This model allows, from the experimental data provided by SAXS, to calculate the composition and volume ratio of the phases. The results indicate that these complexes are nonstoichiometric, containing a lesser amount of DADMAC than surfactant units. The neutral sequences of acrylamide can be considered as bridges along the water domains remaining anchored to the AOT bilayers by the cationic DADMAC units. When the charge density diminishes, the bridges become longer, rendering structures with higher water content.
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Affiliation(s)
- Yahya Agzenai
- Dpt. CC y TT Fisicoquímicas, Facultad de Ciencias, UNED, P° Senda del Rey 9, 28040 Madrid, Spain
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7
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Zheng P, Cai D, Zhang Z, Yang Y, Yin T, Shen W. Interactions between Sodium Polyacrylate and Mixed Micelles of Dodecyltrimethylammonium Bromide and Sodium Bis(2-ethylhexyl) Sulfosuccinate. Macromolecules 2012. [DOI: 10.1021/ma300793m] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peizhu Zheng
- School of Chemistry
and Molecular
Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Dongxing Cai
- Department of Chemistry, Lanzhou University, Lanzhou, Gansu 730000, China
| | - Zhiguo Zhang
- School of Chemistry
and Molecular
Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yan Yang
- School of Chemistry
and Molecular
Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Tianxiang Yin
- School of Chemistry
and Molecular
Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Weiguo Shen
- School of Chemistry
and Molecular
Engineering, East China University of Science and Technology, Shanghai 200237, China
- Department of Chemistry, Lanzhou University, Lanzhou, Gansu 730000, China
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8
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Wang Q, Li HZ, Xie YJ, Li HY, Yang HY. Effect of Potassium Oleate on Rheological Behavior of Cationic Guar in Aqueous Solution with Varying Temperatures. CHINESE J CHEM PHYS 2012. [DOI: 10.1088/1674-0068/25/04/448-456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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9
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Agzenai Y, Renamayor CS, Pacios IE. Nonstoichiometric polymer-surfactant complexes obtained in a lamellar lyotropic medium. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-012-2635-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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10
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Stanic V, Mancuso M, Wong W, DiMasi E, Strey HH. Phase Diagrams of Electrostatically Self-Assembled Amphiplexes. Macromolecules 2011. [DOI: 10.1021/ma201240k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vesna Stanic
- Department of Biomedical Engineering, Bioengineering Bldg, State University of New York at Stony Brook, Stony Brook, New York 11794-5281, United States
| | - Matthew Mancuso
- Department of Biomedical Engineering, Bioengineering Bldg, State University of New York at Stony Brook, Stony Brook, New York 11794-5281, United States
| | - Waiken Wong
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts 10003, United States
| | - Elaine DiMasi
- National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Helmut H. Strey
- Department of Biomedical Engineering, Bioengineering Bldg, State University of New York at Stony Brook, Stony Brook, New York 11794-5281, United States
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11
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Leonard M, Strey HH. Measurement of Phase Transition Free Energies in Polyelectrolyte−Surfactant Complexes. Macromolecules 2010. [DOI: 10.1021/ma9028344] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael Leonard
- Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, Massachusetts 10003
| | - Helmut H. Strey
- Biomedical Engineering Department, Stony Brook University, Stony Brook, New York 11794-2580
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12
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Wu Q, Shangguan Y, Du M, Zhou J, Song Y, Zheng Q. Steady and dynamic rheological behaviors of sodium carboxymethyl cellulose entangled semi-dilute solution with opposite charged surfactant dodecyl-trimethylammonium bromide. J Colloid Interface Sci 2009; 339:236-42. [DOI: 10.1016/j.jcis.2009.07.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 07/15/2009] [Accepted: 07/17/2009] [Indexed: 10/20/2022]
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13
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Angelov B, Angelova A, Vainio U, Garamus VM, Lesieur S, Willumeit R, Couvreur P. Long-living intermediates during a lamellar to a diamond-cubic lipid phase transition: a small-angle X-ray scattering investigation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3734-3742. [PMID: 19708151 DOI: 10.1021/la804225j] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To generate nanostructured vehicles with tunable internal organization, the structural phase behavior of a self-assembled amphiphilic mixture involving poly(ethylene glycol) monooleate (MO-PEG) and glycerol monooleate (MO) is studied in excess aqueous medium by time-resolved small-angle X-ray scattering (SAXS) in the temperature range from 1 to 68 degrees C. The SAXS data indicate miscibility of the two components in lamellar and nonlamellar soft-matter nanostructures. The functionalization of the MO assemblies by a MO-PEG amphiphile, which has a flexible large hydrophilic moiety, appears to hinder the epitaxial growth of a double diamond (D) cubic lattice from the lamellar (L) bilayer structure during the thermal phase transition. The incorporated MO-PEG additive is found to facilitate the formation of structural intermediates. They exhibit greater characteristic spacings and large diffusive scattering in broad temperature and time intervals. Their features are compared with those of swollen long-living intermediates in MO/octylglucoside assemblies. A conclusion can be drawn that long-living intermediate states can be equilibrium stabilized in two- or multicomponent amphiphilic systems. Their role as cubic phase precursors is to smooth the structural distortions arising from curvature mismatch between flat and curved regions. The considered MO-PEG functionalized assemblies may be useful for preparation of sterically stabilized liquid-crystalline nanovehicles for confinement of therapeutic biomolecules.
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Affiliation(s)
- Borislav Angelov
- Institute of Biophysics, Bulgarian Academy of Sciences, BG-1113 Sofia, Bulgaria
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14
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Langevin D. Complexation of oppositely charged polyelectrolytes and surfactants in aqueous solutions. A review. Adv Colloid Interface Sci 2009; 147-148:170-7. [PMID: 18929350 DOI: 10.1016/j.cis.2008.08.013] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 08/19/2008] [Accepted: 08/27/2008] [Indexed: 11/19/2022]
Abstract
Addition of surfactants to aqueous solutions of polyelectrolytes causes the spontaneous formation of complexes in a certain range of concentrations. In some conditions, compact monodisperse multichain complexes are obtained (short surfactant chain length and polymer rigid enough). The size of the complexes can be varied in controlled way from nanometers up to micrometers, but depends on the mixing procedure, whereas the shape of the complexes depends on the polymer backbone rigidity. These complexes exhibit microstructures analogue to that of the precipitates formed at higher concentrations. In most cases, however, the complexes are large, soft and polydisperse.
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Affiliation(s)
- Dominique Langevin
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, Orsay, France
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15
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Nause RG, Hoagland DA, Strey HH. Structural Evolution of Complexes of Poly(styrenesulfonate) and Cetyltrimethylammonium Chloride. Macromolecules 2008. [DOI: 10.1021/ma071634u] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Richard G. Nause
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, and Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11790
| | - David A. Hoagland
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, and Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11790
| | - Helmut H. Strey
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, and Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11790
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16
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Dexter AF, Malcolm AS, Zeng B, Kennedy D, Middelberg APJ. Mixed system of Eudragit s-100 with a designed amphipathic peptide: control of interfacial elasticity by solution composition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:3045-3052. [PMID: 18275234 DOI: 10.1021/la703252r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report an interfacially active system based on an informational peptide surfactant mixed with an oppositely charged polyelectrolyte. The 21-residue cationic peptide, AM1, has previously been shown to respond reversibly to pH and metal ions at fluid interfaces, forming elastic films that can be rapidly switched to collapse foams or emulsions on demand. Here we report the reversible association of AM1 with the methacrylate-based anionic polymer Eudragit S-100. The strength of the association, in bulk aqueous solution, is modulated by added metal ions and by ionic strength. Addition of zinc ions to the peptide-polymer system promotes complex formation and phase separation, while addition of a chelating agent reverses the association. The addition of salt weakens peptide-polymer interactions in the presence or absence of zinc. At the air-water interface, Eudragit S-100 forms an elastic mixed film with AM1 in the absence of metal, under conditions where the peptide alone does not show interfacial elasticity. When zinc is present, the elasticity of the mixed film is increased, but the rate of interfacial adsorption slows due to formation of peptide-polymer complexes in bulk solution. An understanding of these interactions can be used to identify favorable foam-forming conditions in the mixed system.
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Affiliation(s)
- Annette F Dexter
- Centre for Biomolecular Engineering, School of Engineering and Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia QLD 4072 Australia
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17
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Trabelsi S, Albouy PA, Impéror-Clerc M, Guillot S, Langevin D. X-ray Diffraction Study of the Structure of Carboxymethylcellulose–Cationic Surfactant Complexes. Chemphyschem 2007; 8:2379-85. [DOI: 10.1002/cphc.200700378] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Kumar A, Dubin PL, Hernon MJ, Li Y, Jaeger W. Temperature-Dependent Phase Behavior of Polyelectrolyte−Mixed Micelle Systems. J Phys Chem B 2007; 111:8468-76. [PMID: 17580853 DOI: 10.1021/jp067919a] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of temperature on the phase behavior of a polycation-anionic/nonionic mixed micelle system, poly(dimethyldiallylammonium chloride)-sodium dodecylsulfate/Triton X-100, was studied over a wide range of surfactant compositions, ionic strengths, and polycation molecular weights using turbidimetry and dynamic light scattering. Soluble complexes become biphasic upon heating through either liquid-liquid (coacervation) or liquid-solid (precipitation) separation. The biphasic boundary comprises two regions: a coacervate domain exhibiting a lower critical solution temperature and a second superimposed domain in which either solids or very dense and viscous fluids are formed upon heating. The position of the first region is symmetrically centered around conditions corresponding to charge neutralization of complexes and their aggregates at incipient phase separation. The second region, observed at high micelle charge, corresponds to the collapse of polycation onto micelle surfaces and expulsion of counterions and can produce either dense coacervate or precipitate. The two regions exhibit different dependences on ionic strength, polyelectrolyte molecular weight, and concentration, from which inferences about the mechanisms of phase separation may be drawn. Preliminary observations of the dense liquid phases isolated after coacervation disclose a number of interesting optical and rheological properties, possibly arising from shear-induced phase separation.
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Affiliation(s)
- Anil Kumar
- Department of Chemistry, University of Massachusetts at Amherst, Amherst, Massachusetts 01003, USA
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19
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O'Driscoll BMD, Fernandez-Martin C, Wilson RD, Knott J, Roser SJ, Edler KJ. Macroscopic, mesostructured cationic surfactant/neutral polymer films: structure and cross-linking. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:4589-98. [PMID: 17371057 DOI: 10.1021/la063004b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Mesostructured films of alkyltrimethylammonium bromides or cetylpyridinium bromide and polyethylenimines that spontaneously self-assemble at the air/water interface have been examined using a range of surface sensitive techniques. These films are unusual in that they can be micrometers thick and are relatively robust. Here we show that the films can be cross-linked and thus removed from the liquid surface where they form, as solid, mesostructured polymer-surfactant membranes. Cross-linking causes little change in the structure of the films but freezes in the metastable mesostructures, enhancing the potential of these films for future applications. Cross-linked films, dried after removal from the solution surface, retain the ordered nanoscale structure within the film. We also report grazing incidence X-ray diffraction (GID), which shows that most films display scattering consistent with 2D-hexagonal phase crystallites of rodlike surfactant micelles encased in polymer. Polymer branching makes little difference to the film structures; however, polymer molecular weight has a significant effect. Films with lower polymer MW are generally thinner and more ordered, while higher polymer MW films were thicker and less ordered. Increased pH causes formation of thicker films and improves the ordering in low MW films, while high MW films lose order. To rationalize these results, we propose a model for the film formation process that relates the kinetic and thermodynamic limits of phase separation and mesophase ordering to the structures observed.
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20
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Abstract
Structures of concentrated mixtures of associating polymer-surfactant mixtures are important in many technical applications. Yet an in-depth understanding of how molecular parameters affect these structures is lacking. We here summarize the results of ongoing work using a novel simplified approach to the study of associating oppositely charged polymer-surfactant mixtures, introducing a minimum number of components to the various mixtures. The results illustrate the relations between systems with and without polyions, as well as effects of systematic changes of parameters such as surfactant chain length, polyion length, polyion charge density, and the charge density of the surfactant aggregate.
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21
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22
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Leal C, Bilalov A, Lindman B. Phase Behavior of a DNA-Based Surfactant Mixed with Water and n-Alcohols. J Phys Chem B 2006; 110:17221-9. [PMID: 16928021 DOI: 10.1021/jp062151f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The self-assembly behavior of a cationic surfactant (dodecyltrimethylammonium, DTA) with DNA as counterion in mixtures of water and n-alcohols (decanol, octanol, hexanol, butanol, and ethanol) was investigated. The phase diagrams were established and the different regions of the phase diagram characterized with respect to microstructure by (2)H NMR, small-angle X-ray scattering (SAXS), and other techniques. The DNA-DTA surfactant is soluble in all of the studied alcohols, showing increased solubility from decanol down to ethanol. All of the phase diagrams are analogous with respect to the occurrence of liquid crystalline (LC) regions, but the area of the LC region increases as one goes from decanol to ethanol. In all phase diagrams, hexagonal phases (of the reversed type) for the alcohol-rich side and lamellar phases for the other side were detected. For balanced proportions of the components, there is a coexistence of the lamellar and the hexagonal phase, here detected with a double quadrupole splitting in the (2)H NMR spectra. The correctness of the phase diagrams is confirmed by the fact that along the tie-lines the splitting magnitude remains nearly constant. All of the alcohols except for ethanol act as cosurfactants penetrating the DNA-DTA film. Adding salt to the ternary mixtures causes an increase in the unit cell dimension of the lamellar and the hexagonal phases. The phase diagram becomes more complicated when butanol is used for the alcohol phase. Here, there is the occurrence of a new isotropic phase with some properties analogous to those of the disordered sponge (L3) phase obtained for simple surfactant systems.
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Affiliation(s)
- Cecilia Leal
- Physical Chemistry 1, Center of Chemistry and Chemical Engineering, University of Lund, POB 124, Lund 22100, Sweden.
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Pi Y, Shang Y, Peng C, Liu H, Hu Y, Jiang J. Phase behavior of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) and polyelectrolyte NaPAA. J Colloid Interface Sci 2006; 299:410-5. [PMID: 16481000 DOI: 10.1016/j.jcis.2006.01.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Revised: 01/17/2006] [Accepted: 01/18/2006] [Indexed: 12/01/2022]
Abstract
The phase behavior of aqueous mixtures of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and oppositely charged polyelectrolyte sodium polyacrylate (NaPAA) has been studied experimentally. Compared to the mixtures of the traditional surfactant dodecyltrimethylammonium bromide (DTAB) and NaPAA, the gel phase region in the 12-6-12/NaPAA solution is larger. Element analysis reveals that NaPAA in the gel phase tends to replace the counterions of surfactant micelle and to release its own counterions. Spherical aggregates are observed in either top or bottom gel phase as detected by transmission electron microscopy. The addition of sodium bromide (NaBr) leads to a decrease in the gel phase region and the occurrence of a new cream phase.
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Affiliation(s)
- Yingying Pi
- Department of Chemistry and Lab for Advanced Materials, East China University of Science and Technology, Shanghai 200237, China
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Yu Q, Frömmel J, Wolff T, Stepanek M, Procházka K. Lyotropic and thermotropic phase transitions in films of ionene-alkyl sulfate complexes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:6797-804. [PMID: 16008389 DOI: 10.1021/la050907g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Five [X,Y]-ionenes [(CH2)(X)N+(CH3)2(CH2)(Y)N+(CH3)2]nBr-(2n) were prepared (X = 3, 5; Y = 10, 12, 22). Using new preparation methods, dry, salt-free complexes with three n-alkyl sulfates (octyl, decyl, and dodecyl) were obtained. The ionenes and their complexes were characterized in methanol solution by light scattering, viscometry, and fluorescent probe studies. The solid materials were investigated by means of DSC, TG, and ATR-IR. Transparent films were formed from stoichiometric [3,10], [3,12], and [5,10]-ionene complexes with decyl and dodecyl sulfate. In the films, mesogenic phase transitions could be induced: dry films were optically isotropic; when exposed to elevated humidity, the films slowly became optically anisotropic because of a lyotropic transition to a hexagonal mesogenic phase. The relative humidity, at which the hexagonal phase developed, was distinct for each complex. The anisotropic phases were converted to isotropic in a thermotropic transition under controlled relative humidity at specific clearing temperatures, which were higher for dodecyl complexes than for decyl complexes. This thermotropic isotropic-anisotropic transition could be cycled several times, but partial hydrolysis of the alkyl sulfates reduced the reproducibility of transition points.
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Affiliation(s)
- Quanwei Yu
- Institut für Physikalische Chemie und Elektrochemie, Technische Universität Dresden, D-01062 Dresden, Germany
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Naves AF, Petri DF. The effect of molecular weight and degree of substitution on the interactions between carboxymethyl cellulose and cetyltrimethylammonium bromide. Colloids Surf A Physicochem Eng Asp 2005. [DOI: 10.1016/j.colsurfa.2004.12.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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DeRouchey J, Netz RR, Rädler JO. Structural investigations of DNA-polycation complexes. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2005; 16:17-28. [PMID: 15688137 DOI: 10.1140/epje/e2005-00003-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Indexed: 05/24/2023]
Abstract
The internal structure of DNA-polycation complexes is investigated by synchrotron small-angle X-ray scattering (SAXS). Hexagonal packing of DNA is observed for DNA complexed with poly-L-lysine (PL), poly-L-arginine (PA), spermine (Sp), and linear and branched polyethyleneimine (lPEI and bPEI, respectively). Variations in the internal spacings and degree of long-range ordering are dependent on both polycation type and concentration of added salt. With increasing concentration of monovalent salt, a discontinuous phase transition is observed from compact to loose bundles and finally to an isotropic network phase. This salt-induced melting transition was found to be universal for all polyplexes studied and is in quantitative agreement with a simple free energy model based solely on electrostatic and entropic contributions. Using the osmotic stress method, bulk modulus (K) is measured for PL-DNA and PA-DNA polyplexes at various salt concentrations. With increasing osmotic force, we show that the salt-induced melting transition is shifted and compression in the loose bundle regime is in qualitative agreement with our model.
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Affiliation(s)
- J DeRouchey
- Ludwig-Maximilians-Universität, Sektion Physik, Geschwister-Scholl-Platz 1, 80539, Munich, Germany.
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Vaknin D, Dahlke S, Travesset A, Nizri G, Magdassi S. Induced crystallization of polyelectrolyte-surfactant complexes at the gas-water interface. PHYSICAL REVIEW LETTERS 2004; 93:218302. [PMID: 15601067 DOI: 10.1103/physrevlett.93.218302] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2004] [Indexed: 05/24/2023]
Abstract
Synchrotron x-ray and surface-tension studies of a strong polyelectrolyte (PE) in the semidilute regime (approximately 0.1 M monomer charges) with varying surfactant concentrations show that minute surfactant concentrations induce the formation of a PE-surfactant complex at the gas-solution interface. X-ray reflectivity and grazing angle x-ray diffraction show the complex PE-surfactant resides at the interface and the alkyl chains of the surfactant form a two-dimensional liquidlike monolayer. With the addition of salt (NaCl), columnar crystals with distorted-hexagonal symmetry are formed.
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Affiliation(s)
- D Vaknin
- Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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