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Kettiger H, Québatte G, Perrone B, Huwyler J. Interactions between silica nanoparticles and phospholipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2163-2170. [DOI: 10.1016/j.bbamem.2016.06.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 06/17/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022]
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Catte A, Girych M, Javanainen M, Loison C, Melcr J, Miettinen MS, Monticelli L, Määttä J, Oganesyan VS, Ollila OHS, Tynkkynen J, Vilov S. Molecular electrometer and binding of cations to phospholipid bilayers. Phys Chem Chem Phys 2016; 18:32560-32569. [DOI: 10.1039/c6cp04883h] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The molecular electrometer – reorientation of lipid head due to bound charge – allows direct quantitative vetting of simulations against noninvasive NMR experiments; most simulation models overestimated lipid–cation affinities.
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Synthesis and Phase Behavior of Poly( N-isopropylacrylamide)-b- Poly(L-Lysine Hydrochloride) and Poly( N-Isopropylacrylamide- co-Acrylamide)-b-Poly(L-Lysine Hydrochloride). MATERIALS 2014; 7:5305-5326. [PMID: 28788130 PMCID: PMC5455825 DOI: 10.3390/ma7075305] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/08/2014] [Accepted: 07/17/2014] [Indexed: 02/01/2023]
Abstract
The synthesis of poly(N-isopropylacrylamide)-b-poly(L-lysine) and poly(N-isopropylacrylamide-co-acrylamide)-b-poly(L-lysine) copolymers was accomplished by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). For this purpose, a di-functional initiator with protected amino group was successfully synthetized. The ATRP of N-isopropylacrylamide yielded narrowly dispersed polymers with consistent high yields (~80%). Lower yields (~50%) were observed when narrowly dispersed random copolymers of N-isopropylacrylamide and acrylamide where synthesized. Amino-terminated poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-acrylamide) were successfully used as macroinitiators for ROP of N6-carbobenzoxy-L-lysine N-carboxyanhydride. The thermal behavior of the homopolymers and copolymers in aqueous solutions was studied by turbidimetry, dynamic light scattering (DLS) and proton nuclear magnetic resonance spectroscopy (1H-NMR).
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Choi BC, Choi S, Leckband DE. Poly(N-isopropyl acrylamide) brush topography: dependence on grafting conditions and temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:5841-5850. [PMID: 23600842 DOI: 10.1021/la400066d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The topography of poly (N-isopropyl acrylamide) brushes end-grafted from initiator-terminated monolayers was imaged by atomic force microscopy, as a function of the area per chain and of solvent quality. Measurements were done in air and in water, below and above the lower critical solution temperature. At low grafting densities and molecular weights, area-averaged ellipsometry measurements did not detect changes in the volume of water-swollen, end-grafted polymer films above the lower critical solution temperature. However, atomic force microscopy images revealed surface features that suggest the formation of lateral aggregates or "octopus micelles". At high grafting densities and molecular weights, the films collapsed uniformly, as detected by both AFM imaging and ellipsometry. These findings reconcile in part prior results suggesting that some poly(N-isopropyl acrylamide) chains do not collapse in poor solvent, and they also reveal more complex collapse behavior above the lower critical solution temperature than is commonly assumed. This behavior would influence the ability to tune the functional properties of poly(N-isopropyl acrylamide) coatings.
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Affiliation(s)
- B-C Choi
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801, United States
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Jung YD, Park SY. Protein detection using aqueous/LC interfaces decorated with a novel poly(N-isopropyl acrylamide) block liquid crystalline polymer. RSC Adv 2013. [DOI: 10.1039/c3ra42472c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Choi S, Choi BC, Xue C, Leckband D. Protein Adsorption Mechanisms Determine the Efficiency of Thermally Controlled Cell Adhesion on Poly(N-isopropyl acrylamide) Brushes. Biomacromolecules 2012; 14:92-100. [DOI: 10.1021/bm301390q] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Changying Xue
- Department of Biomedical
Engineering, University of California—Los Angeles, Los Angeles, California 90095, United States
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Banerjee S, Pal TK, Guha SK. Probing molecular interactions of poly(styrene-co-maleic acid) with lipid matrix models to interpret the therapeutic potential of the co-polymer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:537-50. [DOI: 10.1016/j.bbamem.2011.12.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 11/18/2011] [Accepted: 12/08/2011] [Indexed: 10/14/2022]
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Xue C, Yonet-Tanyeri N, Brouette N, Sferrazza M, Braun PV, Leckband DE. Protein adsorption on poly(N-isopropylacrylamide) brushes: dependence on grafting density and chain collapse. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8810-8. [PMID: 21662243 PMCID: PMC3412611 DOI: 10.1021/la2001909] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The protein resistance of poly(N-isopropylacrylamide) brushes grafted from silicon wafers was investigated as a function of the chain molecular weight, grafting density, and temperature. Above the lower critical solution temperature (LCST) of 32 °C, the collapse of the water-swollen chains, determined by ellipsometry, depends on the grafting density and molecular weight. Ellipsometry, radio assay, and fluorescence imaging demonstrated that, below the lower critical solution temperature, the brushes repel protein as effectively as oligoethylene oxide-terminated monolayers. Above 32 °C, very low levels of protein adsorb on densely grafted brushes, and the amounts of adsorbed protein increase with decreasing brush-grafting-densities. Brushes that do not exhibit a collapse transition also bind protein, even though the chains remain extended above the LCST. These findings suggest possible mechanisms underlying protein interactions with end-grafted poly(N-isopropyl acrylamide) brushes.
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Affiliation(s)
- Changying Xue
- Department of Chemical and Biomolecular Engineering, 600 South Mathews Laboratory, Urbana, IL 61801
| | - Nihan Yonet-Tanyeri
- Department of Material Science and Engineering, University of Illinois, Urbana, IL 61801
| | - Nicolas Brouette
- Département de Physique, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, CP223, B-1050 Bruxelles, Belgique
| | - Michele Sferrazza
- Département de Physique, Faculté des Sciences, Université Libre de Bruxelles, Boulevard du Triomphe, CP223, B-1050 Bruxelles, Belgique
| | - Paul V. Braun
- Department of Material Science and Engineering, University of Illinois, Urbana, IL 61801
| | - Deborah E. Leckband
- Department of Chemical and Biomolecular Engineering, 600 South Mathews Laboratory, Urbana, IL 61801
- Department of Chemistry, University of Illinois, Urbana, IL 61801
- To whom correspondence should be addressed: Phone: 217-244-0793, Fax: 217-333-5052,
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Saleem Q, Liu B, Gradinaru CC, Macdonald PM. Lipogels: Single-Lipid-Bilayer-Enclosed Hydrogel Spheres. Biomacromolecules 2011; 12:2364-74. [DOI: 10.1021/bm200266z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Qasim Saleem
- Department of Chemistry and ‡Department of Physics, University of Toronto, and §Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario, Canada L5L 1C6
| | - Baoxu Liu
- Department of Chemistry and ‡Department of Physics, University of Toronto, and §Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario, Canada L5L 1C6
| | - Claudiu C. Gradinaru
- Department of Chemistry and ‡Department of Physics, University of Toronto, and §Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario, Canada L5L 1C6
| | - Peter M. Macdonald
- Department of Chemistry and ‡Department of Physics, University of Toronto, and §Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario, Canada L5L 1C6
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Bisht HS, Wan L, Mao G, Oupicky D. pH-Controlled association of PEG-containing terpolymers of N-isopropylacrylamide and 1-vinylimidazole. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.06.080] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
The interactions of hydrophobically-modified poly-(N-isopropylacrylamides) (HM-PNIPAM) and dimyristoylphosphatidylcholine (DMPC) vesicles were investigated by the effect of the polymer on the binding of a fluorescent dye, oxonol VI, to DMPC vesicles, and on its diffusion across the membrane. On mixing with the vesicles, the dye exhibits an increase in fluorescence, which occurs in a two-stage process. The process was monitored by stopped-flow fluorescence spectrophotometry. According to the dependence of the reciprocal relaxation time on vesicle concentration, the rapid stage seems to be due to the second-order binding of the dye to the lipid membrane, a process that is almost diffusion-controlled, whereas the slow process is attributed to movement of the dye within the membrane phase. The polymer did not significantly affect the rate constant of the binding step, but it slowed down slightly the dissociation process of the dye from the membrane. However, the polymer affected the second stage, causing an increase in the reciprocal of its relaxation time, which suggests that the polymer makes the vesicle membrane more fluid.
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Affiliation(s)
- Yan jun Wang
- School of Chemical Technology and Engineering, Tianjin University, 300072, Tianjin, PR China.
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Yaroslavov AA, Melik-Nubarov NS, Kabanov VA, Ermakov YA, Azov VA, Menger FM. Conventional and gemini surfactants embedded within bilayer membranes: contrasting behavior. Chemistry 2001; 7:4835-43. [PMID: 11763452 DOI: 10.1002/1521-3765(20011119)7:22<4835::aid-chem4835>3.0.co;2-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Laser microelectrophoresis (coupled with conductance, fluorescence, and dynamic light scattering) is shown to be a highly instructive tool in comparing the dynamics of conventional and gemini surfactants embedded within vesicle bilayers. The following can be listed among the more important observations and conclusions: a) Cationic conventional surfactant, added to a "solid" (gel) lipid vesicle containing an anionic phospholipid, charge-neutralizes only half the anionic charge. With a "liquid" (liquid crystalline) vesicle, however, the entire negative charge is neutralized. Thus, the cationic conventional surfactant can "flip-flop" readily only in the liquid membrane. b) A cationic gemini surfactant charge-neutralizes only the anionic lipid in the outer membrane leaflet of either solid or liquid membranes, thus indicating an inability to flip-flop regardless of the phase-state of the bilayer. c) Mixed population experiments show that surfactants can hop from one vesicle to another in liquid but not solid membranes. d) In liquid, but not solid, bilayers, a surface-adsorbed cationic polymer can electrostatically "drag" anionic surfactant from the inner leaflet to the outer leaflet where the polymer resides. e) Peripheral fluorescence quenching experiments show that a cationic polymer, adhered to anionic vesicles, can be forced to dissociate in the presence of high concentrations of salt or an anionic polymer. f) Adsorbed polymer, of opposite charge to that imparted to vesicles by a gemini surfactant, is unable to dislocate surfactant even in a liquid membrane. g) In our systems, ionic polymers will not bind to neutral vesicles made solely of zwitterionic phospholipid. On the other hand, ionic polymers bind to neutral vesicles if charge neutrality is obtained by virtue of the membrane containing equimolar amounts of cationic and anionic surfactant. This is attributable to surfactant segregation within the bilayer. h) Experiments prove that polymer migration can occur among a population of neutral ternary vesicles.
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Affiliation(s)
- A A Yaroslavov
- Polymer Department, School of Chemistry, Lomonosov Moscow State University, Russia.
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Affiliation(s)
- D C Drummond
- Research Institute, California Pacific Medical Center, 94115, San Francisco, CA, USA
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