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Shi X, Rao R, Xu M, Dong M, Feng S, Huang Y, Zhou B. Methylcellulose improves dissociation quality of adult human primary cardiomyocytes. Heliyon 2024; 10:e31653. [PMID: 38841456 PMCID: PMC11152705 DOI: 10.1016/j.heliyon.2024.e31653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 05/16/2024] [Accepted: 05/20/2024] [Indexed: 06/07/2024] Open
Abstract
Obtaining high-quality adult human primary cardiomyocytes (hPCM) have been technically challenging due to isolation-induced biochemical and mechanical stress. Building upon a previous tissue slicing-assisted digestion method, we introduced polymers into the digestion solution to reduce mechanical damage to cells. We found that low-viscosity methylcellulose (MC) significantly improved hPCM viability and yield. Mechanistically, it protected cells from membrane damage, which led to decreased apoptosis and mitochondrial reactive oxygen species production. MC also improved the electrophysiological properties of hPCMs by maintaining the density of sodium channels. The effects on cell viability and cell yield effects were not recapitulated by MC of larger viscosities, other cellulose derivatives, nor shear protectants polyethylene glycol and polyvinyl alcohol. Finally, MC also enhanced the isolation efficiency and the culture quality of hPCMs from diseased ventricular myocardium, expanding its potential applications. Our findings showed that the isolation quality of hPCMs can be further improved through the addition of a polymer, rendering hPCMs a more reliable cellular model for cardiac research.
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Affiliation(s)
- Xun Shi
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Rongjia Rao
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Miaomiao Xu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Mengqi Dong
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Shanshan Feng
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Yafei Huang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
| | - Bingying Zhou
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Science and Peking Union Medical College, 167 North Lishi Road, Xicheng District, Beijing, 100037, China
- Shenzhen Key Laboratory of Cardiovascular Disease, Fuwai Hospital Chinese Academy of Medical Science, Shenzhen, Shenzhen, China
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Grigoras AG. Investigation of Cellulose-Based Materials Applied in Life Sciences Using Laser Light Scattering Methods. Polymers (Basel) 2024; 16:1170. [PMID: 38675089 PMCID: PMC11054383 DOI: 10.3390/polym16081170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024] Open
Abstract
This review emphasizes the practical importance of laser light scattering methods for characterizing cellulose and its derivatives. The physicochemical parameters like molecular weights, the radius of gyration, hydrodynamic radius, and conformation will be considered when the reproducibility of polymer behavior in solution is necessary for the subsequent optimization of the property profile of a designed product. Since there are various sources of cellulose, and the methods of cellulose extraction and chemical modification have variable yields, materials with variable molecular weights, and size polydispersity will often result. Later, the molecular masses will influence other physicochemical properties of cellulosic materials, both in solution and solid state. Consequently, the most rigorous determination of these quantities is imperative. In this regard, the following are presented and discussed in this review: the theoretical foundations of the light scattering phenomenon, the evolution of the specific instrumentation and detectors, the development of the detector-coupling techniques which include a light scattering detector, and finally, the importance of the specific parameters of polymers in solution, resulting from the data analysis of light scattering signals. All these aspects are summarized according to the chemical classification of the materials: celluloses, esters of cellulose, co-esters of cellulose, alkyl esters of cellulose, ethers of cellulose, and other heterogeneous cellulose derivatives with applications in life sciences.
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Affiliation(s)
- Anca-Giorgiana Grigoras
- "Petru Poni" Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley, 41A, 700487 Iasi, Romania
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3
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Kwiatkowski AL, Molchanov VS, Kuklin AI, Chesnokov YM, Philippova OE. Salt-Induced Transformations of Hybrid Micelles Formed by Anionic Surfactant and Poly(4-vinylpyridine). Polymers (Basel) 2022; 14:polym14235086. [PMID: 36501481 PMCID: PMC9741239 DOI: 10.3390/polym14235086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/10/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
Salt-induced structural transformation of charged hybrid surfactant/polymer micelles formed by potassium oleate and poly(4-vinylpyridine) was investigated by cryo-TEM, SANS with contrast variation, DLS, and 2D NOESY. Cryo-TEM data show, that at small salt concentration beads-on-string aggregates on polymer chains are formed. KCl induces the transformation of those aggregates into rods, which is due to the screening of the electrostatic repulsion between similarly charged beads by added salt. In a certain range of salt concentration, the beads-on-string aggregates coexist with the rodlike ones. In the presence of polymer, the sphere-to-rod transition occurs at higher salt concentration than in pure surfactant system indicating that hydrophobic polymer favors the spherical packing of potassium oleate molecules. The size of micelles was estimated by DLS. The rods that are formed in the hybrid system are much shorter than those in polymer-free surfactant solution suggesting the stabilization of the semi-spherical endcaps of the rods by embedded polymer. 2D NOESY data evidence that in the spherical aggregates the polymer penetrates deep into the core, whereas in tighter packed rodlike aggregates it is located mainly at core/corona interface. According to SANS with contrast variation, inside the rodlike aggregates the polymer adopts more compact coil conformation than in the beads-on-string aggregates. Such adaptive self-assembled polymer-surfactant nanoparticles with water-insoluble polymer are very promising for various applications including drag reduction at transportation of fluids.
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Affiliation(s)
- Alexander L. Kwiatkowski
- Physics Department, Moscow State University, 119991 Moscow, Russia
- Correspondence: (A.L.K.); (V.S.M.)
| | - Vyacheslav S. Molchanov
- Physics Department, Moscow State University, 119991 Moscow, Russia
- Correspondence: (A.L.K.); (V.S.M.)
| | | | - Yuri M. Chesnokov
- National Research Center, Kurchatov Institute, 123182 Moscow, Russia
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Hill C, Abdullahi W, Dalgliesh R, Crossman M, Griffiths PC. Charge Modification as a Mechanism for Tunable Properties in Polymer-Surfactant Complexes. Polymers (Basel) 2021; 13:2800. [PMID: 34451340 PMCID: PMC8397960 DOI: 10.3390/polym13162800] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/02/2021] [Accepted: 08/17/2021] [Indexed: 11/17/2022] Open
Abstract
Oppositely charged polymer-surfactant complexes are frequently explored as a function of phase space defined by the charge ratio Z, (where Z = [+polymer]/[-surfactant]), commonly accessed through the surfactant concentration. Tuning the phase behaviour and related properties of these complexes is an important tool for optimising commercial formulations; hence, understanding the relationship between Z and bulk properties is pertinent. Here, within a homologous series of cationic hydroxyethyl cellulose (cat-HEC) polymers with minor perturbations in the degree of side chain charge modification, phase space is instead explored through [+polymer] at fixed Cpolymer. The nanostructures were characterised by small-angle neutron scattering (SANS) in D2O solutions and in combination with the oppositely charged surfactant sodium dodecylsulfate (h- or d-SDS). Scattering consistent with thin rods with an average radius of ∼7.7 Å and length of ∼85 Å was observed for all cat-HEC polymers and no significant interactions were shown between the neutral HEC polymer and SDS (CSDS < CMC). For the charge-modified polymers, interactions with SDS were evident and the radius of the formed complexes grew up to ∼15 Å with increasing Z. This study demonstrates a novel approach in which the Z phase space of oppositely charged polymer-surfactant complexes can be controlled at fixed concentrations.
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Affiliation(s)
- Christopher Hill
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK; (C.H.); (W.A.)
| | - Wasiu Abdullahi
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK; (C.H.); (W.A.)
| | - Robert Dalgliesh
- ISIS Neutron and Muon Source, STFC, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxford OX11 0QX, UK;
| | - Martin Crossman
- Unilever Research, Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, UK;
| | - Peter Charles Griffiths
- School of Science, Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK; (C.H.); (W.A.)
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Takayama Y, Matějka L, Kato N. Dynamic gelation of shear-induced filamentous domains for cellulose ether assemblies due to polyion complexation. Carbohydr Polym 2020; 234:115880. [PMID: 32070503 DOI: 10.1016/j.carbpol.2020.115880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/24/2019] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
Abstract
Assemblies of carbohydrate polymers are important in a number of applications and improved methods for their fabrication are increasingly sought after. Herein, we report that an aqueous two-phase system of alginate (Alg) and hydroxypropyl cellulose with poly(methacrylic acid) graft chains (HPC-PMA) facilitated the assembly of Alg/HPC-PMA in both phases. Dynamically formed filamentous domains in a flow field were gelled by rapid complexation with cationic polyethyleneimine (PEI). The fabricated HPC-PMA gel filament morphologies can be switched between the bundled and dissociated gel filaments using a co-flow microfluidic device in response to the amount of supplied PEI crosslinker. Excess complexation of PEI contributes to the fabrication of cationic gel filaments; this contribution results in a dissociated structure due to electrostatic repulsion. In contrast, an appropriate amount of PEI resulted in a bundle structure. The proposed spinning method avoids the risk of nozzle clogging, and enables the one-step spinning of multiple gel filaments.
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Affiliation(s)
- Yuriko Takayama
- Department of Fundamental Engineering, School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan
| | - Libor Matějka
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic
| | - Norihiro Kato
- Department of Fundamental Engineering, School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan.
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6
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Thermal sensitivity and protein anti-adsorption of hydroxypropyl cellulose-g- poly(2-(methacryloyloxy) ethyl phosphorylcholine). Carbohydr Polym 2017; 157:757-765. [DOI: 10.1016/j.carbpol.2016.10.051] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/13/2016] [Accepted: 10/15/2016] [Indexed: 12/22/2022]
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7
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Li J, Fan T, Xu Y, Wu X. Ionic liquids as modulators of physicochemical properties and nanostructures of sodium dodecyl sulfate in aqueous solutions and potential application in pesticide microemulsions. Phys Chem Chem Phys 2016; 18:29797-29807. [DOI: 10.1039/c6cp04722j] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The change of morphology of ILs/SDS aggregates with increased concentration of ILs.
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Affiliation(s)
- Jing Li
- College of Science
- China Agricultural University
- China
| | - Tengfei Fan
- College of Resources and Environmental Sciences
- China Agricultural University
- China
| | - Yong Xu
- College of Science
- China Agricultural University
- China
| | - Xuemin Wu
- College of Science
- China Agricultural University
- China
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8
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Association of anionic surfactant and physisorbed branched brush layers probed by neutron and optical reflectometry. J Colloid Interface Sci 2015; 440:245-52. [DOI: 10.1016/j.jcis.2014.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 10/29/2014] [Accepted: 11/02/2014] [Indexed: 11/18/2022]
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9
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Natural and synthetic biomaterials for controlled drug delivery. Arch Pharm Res 2013; 37:60-8. [PMID: 24197492 DOI: 10.1007/s12272-013-0280-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
Abstract
A wide variety of delivery systems have been developed and many products based on the drug delivery technology are commercially available. The development of controlled-release technologies accelerated new dosage form design by altering pharmacokinetic and pharmacodynamics profiles of given drugs, resulting in improved efficacy and safety. Various natural or synthetic polymers have been applied to make matrix, reservoir or implant forms due to the characteristics of polymers, especially ease of control for modifications of biocompatibility, biodegradation, porosity, charge, mechanical strength and hydrophobicity/hydrophilicity. Hydrogel is a hydrophilic, polymeric network capable of imbibing large amount of water and biological fluids. This review article introduces various applications of natural and synthetic polymer-based hydrogels from pharmaceutical, biomedical and bioengineering points of view.
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10
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Liu Y, Wu Z, Zhang Y, Yuan H. Partitioning of biomolecules in aqueous two-phase systems of polyethylene glycol and nonionic surfactant. Biochem Eng J 2012. [DOI: 10.1016/j.bej.2012.08.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Abdelbary AA, Li X, El-Nabarawi M, Elassasy A, Jasti B. Effect of fixed aqueous layer thickness of polymeric stabilizers on zeta potential and stability of aripiprazole nanosuspensions. Pharm Dev Technol 2012; 18:730-5. [PMID: 23033924 DOI: 10.3109/10837450.2012.727001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The aim of this study was to evaluate the effect of the thickness of adsorbed polymer layer (also known as Fixed Aqueous Layer Thickness, FALT) of polymeric stabilizers on zeta potential and stability of nanoparticles in a suspension. Aripiprazole, a poorly water soluble drug was used as a model drug to evaluate rationale for increased FALT and to understand the effect of hydrophilicity and hydrophobicity of polymeric stabilizers on FALT of aripiprazole nanosuspensions. The nanosuspensions were prepared by media milling and Pluronic F68, Pluronic F127, Hydroxypropyl methylcellulose (HPMC) and Hydroxypropyl cellulose (HPC) were used as polymeric stabilizers. The particle size (immediately after preparation and after 1 week of storage at 25°C) and zeta potential of aripiprazole nanosuspensions were determined. For Pluronics, FALT was determined theoretically whereas for HPMC and HPC it was calculated as Debye Huckel parameter from the zeta potential dependence on the ionic strength. An increase in FALT resulted in reduced zeta potential. With an increase in FALT of polymers used, the stability of nanosuspensions showed improvement. Furthermore, a linear correlation was shown to exist between the FALT and length of hydrophilic chains in Pluronics.
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Affiliation(s)
- Aly A Abdelbary
- Thomas J. Long School of Pharmacy & Health Sciences, University of Pacific, Stockton, CA, USA
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12
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Boissier C, Feidt F, Nordstierna L. Study of Pharmaceutical Coatings by Means of NMR Cryoporometry and Sem Image Analysis. J Pharm Sci 2012; 101:2512-22. [DOI: 10.1002/jps.23160] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/27/2012] [Accepted: 03/30/2012] [Indexed: 11/08/2022]
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13
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Fettaka M, Issaadi R, Moulai-Mostefa N, Dez I, Cerf DL, Picton L. Thermo sensitive behavior of cellulose derivatives in dilute aqueous solutions: From macroscopic to mesoscopic scale. J Colloid Interface Sci 2011; 357:372-8. [DOI: 10.1016/j.jcis.2011.02.041] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 02/16/2011] [Accepted: 02/17/2011] [Indexed: 11/17/2022]
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14
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Li Y, Chen X, Zhang X, Zhu F, Zhu Y. Complexation behaviour of cellulose derivative/surfactant mixtures investigated by nonlinear enhanced Rayleigh scattering. Colloid Polym Sci 2011. [DOI: 10.1007/s00396-011-2390-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Dupuis G, Rigolini J, Clisson G, Rousseau D, Tabary R, Grassl B. Determination of the Macromolecular Dimensions of Hydrophobically Modified Polymers by Micellar Size Exclusion Chromatography Coupled With Multiangle Light Scattering. Anal Chem 2009; 81:8993-9001. [DOI: 10.1021/ac901527t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Guillaume Dupuis
- Institute Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux (IPREM) UMR CNRS, Université de Pau et des Pays de l’Adour (UPPA) 5254, Hélioparc Pau Pyrénées, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France, and Institut Français du Pétrole (IFP), 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison Cedex, France
| | - Julien Rigolini
- Institute Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux (IPREM) UMR CNRS, Université de Pau et des Pays de l’Adour (UPPA) 5254, Hélioparc Pau Pyrénées, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France, and Institut Français du Pétrole (IFP), 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison Cedex, France
| | - Gérald Clisson
- Institute Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux (IPREM) UMR CNRS, Université de Pau et des Pays de l’Adour (UPPA) 5254, Hélioparc Pau Pyrénées, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France, and Institut Français du Pétrole (IFP), 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison Cedex, France
| | - David Rousseau
- Institute Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux (IPREM) UMR CNRS, Université de Pau et des Pays de l’Adour (UPPA) 5254, Hélioparc Pau Pyrénées, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France, and Institut Français du Pétrole (IFP), 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison Cedex, France
| | - René Tabary
- Institute Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux (IPREM) UMR CNRS, Université de Pau et des Pays de l’Adour (UPPA) 5254, Hélioparc Pau Pyrénées, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France, and Institut Français du Pétrole (IFP), 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison Cedex, France
| | - Bruno Grassl
- Institute Pluridisciplinaire de Recherche sur l’Environnement et les Matériaux (IPREM) UMR CNRS, Université de Pau et des Pays de l’Adour (UPPA) 5254, Hélioparc Pau Pyrénées, 2 Avenue du Président Angot, 64053 Pau Cedex 09, France, and Institut Français du Pétrole (IFP), 1 & 4 Avenue de Bois Préau, 92852 Rueil-Malmaison Cedex, France
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de Vos WM, Biesheuvel PM, de Keizer A, Kleijn JM, Cohen Stuart MA. Adsorption of anionic surfactants in a nonionic polymer brush: experiments, comparison with mean-field theory, and implications for brush-particle interaction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9252-61. [PMID: 19719223 DOI: 10.1021/la900791b] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The adsorption of the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS) in poly(ethylene oxide) (PEO) brushes was studied using a fixed-angle optical flow-cell reflectometer. We show that, just as in solution, there is a critical association concentration (CAC) for the surfactants at which adsorption in the PEO brush starts. Above the critical micelle concentration (CMC) the adsorption is found to be completely reversible. At low brush density the adsorption per PEO monomer is equal to the adsorption of these surfactants in bulk solution. However, with increasing brush density, the number of adsorbed surfactant molecules per PEO monomer decreases rapidly. This decrease is explained in terms of excluded volume interactions plus electrostatic repulsion between the negatively charged surfactant micelles. Experimentally, a plateau value in the total adsorption is observed as a function of grafting density. The experimental results were compared to the results of an analytical self-consistent field (aSCF) model, and we found quantitative agreement. Additionally, the model predicts that the plateau value found is in fact a maximum. Both experiments and model calculations show that the adsorption scales directly with the polymerization degree of the polymers in the brush. They also show that an increase in the ionic strength leads to an increase in the adsorbed amount, which is explained as being due to a decrease in the electrostatic penalty for the adsorption of the SDS micelles. The adsorption of SDS micelles changes the interactions of the PEO brush with a silica particle. This is illustrated by atomic force microscopy (AFM) measurements of the pull-off force of a silica particle from a PEO brush: at high enough PEO densities, the addition of SDS leads to a very strong reduction in the force necessary to detach the colloidal silica particle from the PEO brush. We attribute this effect to the large amount of negative charge incorporated in the PEO brush due to SDS adsorption.
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Affiliation(s)
- Wiebe M de Vos
- Laboratory of Physical Chemistry and Colloid Science, Department of Environmental Technology, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
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17
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Miksanova M, Igarashi J, Minami M, Sagami I, Yamauchi S, Kurokawa H, Shimizu T. Characterization of heme-regulated eIF2alpha kinase: roles of the N-terminal domain in the oligomeric state, heme binding, catalysis, and inhibition. Biochemistry 2006; 45:9894-905. [PMID: 16893190 DOI: 10.1021/bi060556k] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Heme-regulated eIF2alpha kinase [heme-regulated inhibitor (HRI)] plays a critical role in the regulation of protein synthesis by heme iron. The kinase active site is located in the C-terminal domain, whereas the N-terminal domain is suggested to regulate catalysis in response to heme binding. Here, we found that the rate of dissociation for Fe(III)-protoporphyrin IX was much higher for full-length HRI (1.5 x 10(-)(3) s(-)(1)) than for myoglobin (8.4 x 10(-)(7) s(-)(1)) or the alpha-subunit of hemoglobin (7.1 x 10(-)(6) s(-)(1)), demonstrating the heme-sensing character of HRI. Because the role of the N-terminal domain in the structure and catalysis of HRI has not been clear, we generated N-terminal truncated mutants of HRI and examined their oligomeric state, heme binding, axial ligands, substrate interactions, and inhibition by heme derivatives. Multiangle light scattering indicated that the full-length enzyme is a hexamer, whereas truncated mutants (truncations of residues 1-127 and 1-145) are mainly trimers. In addition, we found that one molecule of heme is bound to the full-length and truncated mutant proteins. Optical absorption and electron spin resonance spectra suggested that Cys and water/OH(-) are the heme axial ligands in the N-terminal domain-truncated mutant complex. We also found that HRI has a moderate affinity for heme, allowing it to sense the heme concentration in the cell. Study of the kinetics showed that the HRI kinase reaction follows classical Michaelis-Menten kinetics with respect to ATP but sigmoidal kinetics and positive cooperativity between subunits with respect to the protein substrate (eIF2alpha). Removal of the N-terminal domain decreased this cooperativity between subunits and affected the other kinetic parameters including inhibition by Fe(III)-protoporphyrin IX, Fe(II)-protoporphyrin IX, and protoporphyrin IX. Finally, we found that HRI is inhibited by bilirubin at physiological/pathological levels (IC(50) = 20 microM). The roles of the N-terminal domain and the binding of heme in the structural and functional properties of HRI are discussed.
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Affiliation(s)
- Marketa Miksanova
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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18
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Ma R, Zhang L. Molecular weight and arm number of a star-shaped styrene–butadiene block copolymer synthesized on a pilot-vessel scale. J Appl Polym Sci 2006. [DOI: 10.1002/app.25352] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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19
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Szczubiałka K, Rosół K, Nowakowska M. Smart anionic polyelectrolytes based on natural polymer for complexation of cationic surfactant. J Appl Polym Sci 2006. [DOI: 10.1002/app.24509] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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