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Has C, Sunthar P. A comprehensive review on recent preparation techniques of liposomes. J Liposome Res 2019; 30:336-365. [DOI: 10.1080/08982104.2019.1668010] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- C. Has
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - P. Sunthar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
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Zairov RR, Solovieva AO, Shamsutdinova NA, Podyachev SN, Shestopalov MA, Pozmogova TN, Miroshnichenko SM, Mustafina AR, Karasik AA. Polyelectrolyte-coated ultra-small nanoparticles with Tb(III)-centered luminescence as cell labels with unusual charge effect on their cell internalization. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2018; 95:166-173. [PMID: 30573238 DOI: 10.1016/j.msec.2018.10.084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 09/26/2018] [Accepted: 10/25/2018] [Indexed: 01/28/2023]
Abstract
The present work reports ultra-small polyelectrolyte-coated water insoluble Tb(III) complex species with bright Tb(III)-centered luminescence resulted from efficient ligand-to-metal energy transfer as efficient labels for Hep-2 cells. The flow cytometry data revealed the enhanced cellular uptake of negatively charged nanoparticles coated by the polystyrenesulfonate (PSS)-monolayer versus the positively charged nanoparticles. The latter are obtained by layer-by-layer deposition of polyethyleneimine (PEI) onto PSS-coated ones. Confocal and TEM images of Hep-2 cells exposed by the colloids confirm favorable cell internalization of the PSS- compared to PEI-PSS-coated colloids illustrating unusual charge-effect. Dynamic light scattering data indicate significant effect of the biological background exemplified by serum bovine albumin and phosphatidylcholine-based bilayers on the exterior charge and aggregation behavior of the colloids. The obtained results reveal the PSS-coated nanoparticles based on water insoluble Tb(III) complex as promising cell labels.
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Affiliation(s)
- Rustem R Zairov
- A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences, Arbuzov str., 8, 420088 Kazan, Russian Federation; Kazan (Volga region) Federal University, Kremlyovskaya str., 18, 420008 Kazan, Russian Federation.
| | - Anastasiya O Solovieva
- Scientific Institute of Clinical and Experimental Lymphology - Branch of the ICG SB RAS, 2 Timakova str., 630060 Novosibirsk, Russian Federation
| | - Nataliya A Shamsutdinova
- A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences, Arbuzov str., 8, 420088 Kazan, Russian Federation
| | - Sergey N Podyachev
- A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences, Arbuzov str., 8, 420088 Kazan, Russian Federation
| | - Michael A Shestopalov
- Scientific Institute of Clinical and Experimental Lymphology - Branch of the ICG SB RAS, 2 Timakova str., 630060 Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova str., 630090 Novosibirsk, Russian Federation; Nikolaev Institute of Inorganic Chemistry SB RAS, 3 Acad. Lavrentieva ave., 630090 Novosibirsk, Russian Federation
| | - Tatiana N Pozmogova
- Scientific Institute of Clinical and Experimental Lymphology - Branch of the ICG SB RAS, 2 Timakova str., 630060 Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova str., 630090 Novosibirsk, Russian Federation
| | - Svetlana M Miroshnichenko
- Scientific Institute of Clinical and Experimental Lymphology - Branch of the ICG SB RAS, 2 Timakova str., 630060 Novosibirsk, Russian Federation; Scientific Institute of Biochemistry, 2 Timakova str., 630060 Novosibirsk, Russian Federation
| | - Asiya R Mustafina
- A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences, Arbuzov str., 8, 420088 Kazan, Russian Federation
| | - Andrey A Karasik
- A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of Russian Academy of Sciences, Arbuzov str., 8, 420088 Kazan, Russian Federation
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Mukhametshina AR, Mustafina AR, Davydov NA, Fedorenko SV, Nizameev IR, Kadirov MK, Gorbatchuk VV, Konovalov AI. Tb(III)-doped silica nanoparticles for sensing: effect of interfacial interactions on substrate-induced luminescent response. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 31:611-619. [PMID: 25511410 DOI: 10.1021/la503074p] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The present work introduces the easy modification of the water-in-oil microemulsion procedure aimed at the doping of the Tb(III) complexes within core or shell zones of the silica nanoparticles (SNs), which are designated as "core-shell", "shell", and "core". The dye molecules, chelating ligands, and copper ions were applied as the quenchers of Tb(III)-centered luminescence through dynamic or/and static mechanisms. The binding of the quenchers at the silica/water interface results in the quenching of the Tb(III) complexes within SNs, which, in turn, is greatly dependent on the synthetic procedure. The luminescence of "core" SNs remains unchanged under the binding of the quenchers at the silica/water interface. The quenching through dynamic mechanism is more significant for "core-shell" and "shell" than for "core" SNs. Thus, both "core-shell" and "shell" SNs have enough percentage of the Tb(III) complexes located close to the interface for efficient quenching through the energy transfer. The quenching through the ion or ligand exchange is most efficient for "core-shell" SNs due to the greatest percentage of the Tb(III) complexes at the silica/water interface, which correlates with the used synthetic procedure. The highlighted regularities introduce the applicability of "core-shell" SNs used as silica beads for phosphatidylcholine bilayers in sensing their permeability toward the quenching ions.
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Affiliation(s)
- Alsu R Mukhametshina
- Kazan Federal University , Kremlyovskaya str. 18, 420008, Kazan, Russian Federation
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4
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Yoshida E. PH response behavior of giant vesicles comprised of amphiphilic poly(methacrylic acid)-block-poly(methyl methacrylate-random-mathacrylic acid). Colloid Polym Sci 2014. [DOI: 10.1007/s00396-014-3482-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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5
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Mukhametshina AR, Mustafina AR, Davydov NA, Nizameev IR, Kadirov MK, Gorbatchuk VV, Konovalov AI. The energy transfer based fluorescent approach to detect the formation of silica supported phosphatidylcholine and phosphatidylserine containing bilayers. Colloids Surf B Biointerfaces 2014; 115:93-9. [DOI: 10.1016/j.colsurfb.2013.11.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 11/12/2013] [Accepted: 11/15/2013] [Indexed: 11/25/2022]
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6
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Genç R, Ortiz M, O'Sullivan CK. Curvature-tuned preparation of nanoliposomes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12604-12613. [PMID: 19856992 DOI: 10.1021/la901789h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Numerous methods have been reported for the preparation of liposomes, many of which, in addition to requiring time-consuming preparative steps and the use of organic solvents, result in heterogeneous liposome populations of incontrollable size. Taking into consideration the phenomenon of spontaneous vesiculation and the theory of curvature, here we present an extremely rapid and simple, solvent-free method for the preparation of monodisperse solutions of highly stable small unilamellar vesicles using both charged and zwitterionic lipids mixed with lyso-palmitoylphosphatidylcholine, exploiting a combination of a rapid pH change followed by a defined period of equilibration. Various experimental parameters and their interactions were evaluated in terms of their effect on resulting liposome size and shape, as well as on liposome stability and size distribution, with transmission electron microscope imaging being used to visualize the formed liposomes, and photon correlation spectroscopy to obtain statistical data on mean diameter and monodispersity of the liposome population. zeta potential measurements also provided information about the interpretation of vesiculation kinetics and liposome stability. The time interval of pH jump, operation temperature, equilibration time, and lipid type were shown to be the determining factors controlling the size, shape, and monodispersity of the liposomes. Buffer type was also found to be important for the long-term storage of the liposomes. Ongoing work is looking at the application of the developed method for encapsulation of bioactive molecules, such as drugs, genetic materials, and enzymes.
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Affiliation(s)
- Rükan Genç
- Nanobiotechnology and Bioanalysis Group, Department of Chemical Engineering, Universitat Rovira I Virgili, Av. Paisos Catalans, 26, 43007 Tarragona, Spain
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7
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Lasic DD. Kinetic and Thermodynamic Effects in the Formation of Amphiphilic Colloidal Particles. J Liposome Res 2008. [DOI: 10.3109/08982109309148214] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Wang G, Hollingsworth RI. Synthesis and Properties of a Bipolar, Bisphosphatidyl Ethanolamine That Forms Stable 2-Dimensional Self-Assembled Bilayer Systems and Liposomes. J Org Chem 1999. [DOI: 10.1021/jo9902852] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Guijun Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
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Szleifer I, Gerasimov OV, Thompson DH. Spontaneous liposome formation induced by grafted poly(ethylene oxide) layers: theoretical prediction and experimental verification. Proc Natl Acad Sci U S A 1998; 95:1032-7. [PMID: 9448280 PMCID: PMC18662 DOI: 10.1073/pnas.95.3.1032] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Spontaneous liposome formation is predicted in binary mixtures of fluid phase phospholipids and poly(n)ethylene oxide (PEO)-bearing lipids by using single chain mean field theory. The range of stability of the spontaneous liposomes is determined as a function of percentage of PEO-conjugated lipids and polymer molecular weight. These predictions were tested by using cast films of 1, 2-diacyl-sn-glycerophosphocholines (e.g., egg L-alpha-lecithin, 1, 2-dimyristoyl-sn-glycero-3-phosphocholine, 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine, and 1, 2-distearoyl-sn-glycero-3-phosphocholine) and 1, 2-dipalmitoyl-sn-glycerophosphatidylethanolamine-PEO conjugates (i.e. , 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxypoly(e thylen e glycol)2000]carboxamide and 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxypoly(e thylen e oxide)5000]carboxamide) that were hydrated above their gel-liquid crystal phase transition temperatures. Particle sizes of the resulting dispersions, analyzed by quasielastic light scattering, solute retention, 31P NMR, and freeze-fracture electron microscopy measurements, confirmed the single chain mean field predictions. These data indicate that thermodynamically stable, unilamellar liposomes are formed spontaneously by simple hydration of fluid phase phospholipid bilayer films containing low molar ratios of PEO-based amphiphiles. They further suggest that the equilibrium size and colloidal properties of fluid phase, PEO-modified liposomes can be predicted by using this theoretical approach. The implication of these results on the design and processing of sterically stabilized liposomes used in drug delivery applications also is described.
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Affiliation(s)
- I Szleifer
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393, USA.
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11
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Interaction and translocation of cysteamine (mercaptoethylamine) with model membranes: a 15N-NMR and 1H-NMR study. Eur J Pharm Biopharm 1997. [DOI: 10.1016/s0939-6411(96)00012-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Chenite A, Page YL, Karra VR, Sayari A. Coaxial cylindrical bilayer growth: a novel phase in inorganic–surfactant systems evidenced by transmission electron microscopy. Chem Commun (Camb) 1996. [DOI: 10.1039/cc9960000413] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Abstract
The physical concepts underlying the lateral distribution of the components forming a lamellar assembly of amphiphiles are discussed in this review. The role of amphiphiles' molecular structure and/or aqueous environment (ionic strength, water soluble substances) on formation and stability of lateral patterns is investigated. A considerable effort is devoted to the analysis of the properties of patterned structure which can be different from those of randomly mixed multi-component lamellae. Examples include adhesion and fusion among laterally inhomogeneous bilayers, enhanced interfacial adsorption of ions and polymers, enhanced transport across the bilayer, modified mechanical properties, local stabilization of non-planar geometries (pores, edges) and related phenomena (electroporation, budding transition and so on). Furthermore, an analysis of chemical reactivity within or at the water interface of a laterally inhomogeneous bilayer is briefly discussed. A link between these concepts and experimental findings taken from the biological literature is attempted throughout the review.
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Affiliation(s)
- A Raudino
- Dipartimento di Scienze Chimiche, Università di Catania, Italy
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14
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Swairjo MA, Seaton BA, Roberts MF. Effect of vesicle composition and curvature on the dissociation of phosphatidic acid in small unilamellar vesicles--a 31P-NMR study. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1191:354-61. [PMID: 8172921 DOI: 10.1016/0005-2736(94)90186-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Sonicated small unilamellar vesicles (SUVs) containing phosphatidic acid (PA) give two PA 31P-NMR resonances corresponding to PA molecules in the inner and outer leaflets of the bilayer. This NMR differentiation between the two monolayers is not due to a pH gradient across the membrane but instead reflects differential packing in the inner and outer leaflets imposed by the highly curved SUV surface. The apparent pKa of the outer-leaflet PA increases with decreasing surface curvature and with increasing PA content. The estimated relationship between the apparent pKa of the outer-leaflet PA headgroup and vesicle curvature may provide a qualitative probe for effects related to surface curvature in these model-membrane systems.
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Affiliation(s)
- M A Swairjo
- Department of Physiology, Boston University School of Medicine, MA 02118
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Lin BZ, Yin CC, Hauser H. The effect of positive and negative pH-gradients on the stability of small unilamellar vesicles of negatively charged phospholipids. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1147:237-44. [PMID: 8476917 DOI: 10.1016/0005-2736(93)90008-n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The stability of small unilamellar vesicles (SUV) made from negatively-charged phosphatidate by ultrasonication or pH-jump has been investigated. As criteria for the vesicle stability are used: (I) the bilayer integrity as judged from the permeability of the fluorescent probe carboxyfluorescein (CF) and (II) the susceptibility of the phospholipid vesicles to fusion as judged by gel filtration and freeze-fracture electron microscopy. Egg phosphatidate SUV (PA-SUV) whose internal cavity is in equilibrium with the dispersion medium are strictly speaking thermodynamically unstable by these criteria. They may, however, be regarded as stable from a practical point of view. CF-release is observed with a half-time of 14 days and also some vesicle fusion, particularly at low temperature (4 degrees C). The small effects observed, e.g., the small tendency of the vesicles to undergo fusion is probably due to the high surface charge density of PA bilayers. A main finding of this work is that the same positive pH-gradient which is used in the pH-jump method to drive the formation of SUV from large phosphatidic acid bilayer sheets has a stabilizing effect on the resulting PA-SUV. Stabilization is achieved by positive pH-gradients of about two pH-units or more with the pH of the external medium exceeding the pH of the vesicle cavity. Under these conditions, up to about 8 weeks no significant loss of entrapped CF and no fusion of SUV was observed both at 4 degrees C and room temperature. In contrast, a reverse or negative pH-gradient of several pH units applied to PA-SUV (with the external pH being lower than that of the vesicle cavity) destabilizes PA-SUV. Such a gradient can be shown to lead to a dramatic perturbation of the lipid bilayer packing as evident from a significant increase in CF permeability. The local perturbation of the phospholipid bilayer is accompanied by massive vesicle fusion which is prominent at low temperature (4 degrees C).
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Affiliation(s)
- B Z Lin
- Laboratorium für Biochemie, Eidgenössische Technische Hochschule Zürich, ETH-Zentrum, Switzerland
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16
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Désormeaux A, Laroche G, Bougis PE, Pézolet M. Characterization by infrared spectroscopy of the interaction of a cardiotoxin with phosphatidic acid and with binary mixtures of phosphatidic acid and phosphatidylcholine. Biochemistry 1992; 31:12173-82. [PMID: 1457413 DOI: 10.1021/bi00163a029] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effect of cardiotoxin IIa from Naja mossambica mossambica, a small basic protein extracted from snake venom, on dimyristoylphosphatidic acid (DMPA) and on equimolar mixtures of DMPA and dimyristoylphosphatidylcholine (DMPC) has been studied by Fourier transform infrared spectroscopy. The interaction of cardiotoxin with DMPA dispersions decreases both the cooperativity of the phase transition of the lipid and the molecular order of the lipid acyl chains in the gel phase. This effect increases with the proportion of the toxin in the complexes and leads to the total abolition of the phase transition of DMPA at a lipid-to-protein molar ratio of 5. Small-angle X-ray results demonstrate that the structure of the lipid-protein complexes is poorly ordered and gives rise to broad diffusion peaks rather than to well-resolved diffraction patterns. Infrared spectra of oriented cardiotoxin-DMPA films show that the protein is not homogeneously oriented with respect to the bilayer surface. The destabilization of the gel-phase structure of DMPA by cardiotoxin also results in a deeper water penetration in the interfacial region of the lipid since more carbonyl ester groups appear to be hydrogen bonded in the presence of the toxin. The infrared results on the phosphate group vibrations also indicate clearly that the basic residues of cardiotoxin interact strongly with the phosphate group of DMPA that becomes partly ionized at a pH as low as 6.5. The results obtained on the interaction of cardiotoxin with an equimolar mixture of DMPA and DMPC clearly demonstrate the ability of this toxin to induce lateral phase separation in this mixture with one phase containing DMPA-rich domains perturbed by cardiotoxin while the second phase is composed of regions enriched in DMPC. Comparison of the results of the current study with those obtained on other basic proteins and polypeptides suggests that charge-induced phase separation occurs only when the charge density on certain regions of the protein structure is high enough to lead to efficient electrostatic interactions with anionic phospholipids. This condition occurs only when the conformation of the protein or polypeptide is well-ordered at the lipid interface.
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Affiliation(s)
- A Désormeaux
- Centre de Recherche en Sciences et en Ingénierie des Macromolécules, Département de Chimie, Université Laval, Québec, Canada
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Keller G, Ben-Shaul Y, Bacher A. Influence of metabolic inhibitors on the degradation of tight junctions in HT29 cells. Exp Cell Res 1992; 200:16-25. [PMID: 1563485 DOI: 10.1016/s0014-4827(05)80066-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The human colon adenocarcinoma cell line HT 29 grows in culture without tight junctions (TJ). Tight junction strands of the fascia occludens type can be induced by treatment with proteases and are subsequently degraded during a period of about 3 h. Experiments using a variety of metabolic inhibitors such as 2-deoxyglucose, 2,4-dinitrophenol, and CCCP show that the degradation of TJ is retarded under conditions of ATP depletion. Thus it appears that the removal of TJ from the cell surface is an energy-dependent process. Moreover, DNP can specifically inhibit the degradation of TJ even in the absence of ATP depletion. The possible involvement of a proton gradient in the mechanism of TJ degradation is discussed.
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Affiliation(s)
- G Keller
- Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, Federal Republic of Germany
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Yin CC, Schurtenberger P, Wehrli E, Paltauf F, Hauser H. The effect of monoacylglycerol on the phase behavior of egg phosphatidylcholine. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1070:33-42. [PMID: 1751536 DOI: 10.1016/0005-2736(91)90143-v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Phosphatidylcholine bilayers can accommodate large quantities of monoacylglycerol. Incorporating up to 40% monoacylglycerol has little effect on the orientation and motion of the phosphatidylcholine polar group. Briefly heating mixed dispersions of 1-monooleoylglycerol/egg phosphatidylcholine (1:1, weight ratio; 2.1:1, mole ratio) to 50-60 degrees C induced spontaneous vesiculation: unilamellar and some oligolamellar vesicles bud off the large multilamellar particles. The size of the resulting vesicles ranges from 100 to 1000 nm, with the bulk of the vesicles having diameters between 100 and 500 nm. The spontaneous vesiculation process is reflected in the visual clearance of the mixed lipid dispersion and in the collapse of the 31P powder NMR spectrum to a sharp, asymmetric peak. The narrowing of the 31P-NMR spectrum is explained in terms of additional molecular and/or segmental motion of the lipid polar groups. In mixed dispersions of 1-monooleoylglycerol/egg phosphatidylcholine containing an excess of 1-monooleoylglycerol (greater than or equal to 50%) domain formation takes place, i.e., the formation of local clusters enriched in either of the two lipids. As a result the mechanical properties of these mixed lipid bilayers seem to be quite different from those of pure egg phosphatidylcholine.
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Affiliation(s)
- C C Yin
- Laboratorium für Biochemie, Eidgenössische Technische Hochschule Zürich, ETH-Zentrum, Switzerland
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