Calorimetric and EPR studies of the thermotropic phase behavior of phospholipid membranes

Pentak, Danuta; Sułkowski, Wieslaw W.; Sułkowska, Anna

doi:10.1007/s10973-007-8653-z

Cited by 24 publications

(11 citation statements)

References 40 publications

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“…Differential scanning calorimetry (DSC) curves of aqueous dispersions of pure lipids and their mixtures were recorded between 298–333/K on DSC 2920 by TA Instruments [10,11–13]. Typically, a 10 μl aliquot of lipid dispersion was placed in a hermatically sealed aluminum pan for recording each curve.…”

Section: Methodsmentioning

confidence: 99%

Design of liposomes containing photopolymerizable phospholipids for triggered release of contents

Yavlovich

Singh

Tarasov

et al. 2009

J Therm Anal Calorim

132

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We describe a novel class of light-triggerable liposomes prepared from a photo-polymerizable phospholipid DC8,9PC (1,2- bis (tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine) and DPPC (1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine). Exposure to UV (254 nm) radiation for 0–45 minutes at 25°C resulted in photo-polymerization of DC8,9PC in these liposomes and the release of an encapsulated fluorescent dye (calcein). Kinetics and extents of calcein release correlated with mol% of DC8,9PC in the liposomes. Photopolymerization and calcein release occurred only from DPPC/DC8,9PC but not from Egg PC/DC8,9PC liposomes. Our data indicate that phase separation and packing of polymerizable lipids in the liposome bilayer are major determinants of photo-activation and triggered contents release.

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Section: Methodsmentioning

confidence: 99%

Design of liposomes containing photopolymerizable phospholipids for triggered release of contents

Yavlovich

Singh

Tarasov

et al. 2009

J Therm Anal Calorim

132

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“…However, it is still not easy to prepare acceptable aseptic liposomal drugs with desirable properties, high encapsulation efficiency, and long-term stability without drug leakage and loss [3]. When liposomes are used as drug carriers, their size is of major importance, since this influences the behavior of liposomes in biological systems [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…In this report, we have presented the small liposomes prepared by the modified REV method [7] with the desirable properties of the relatively high encapsulation efficiency of antitumor drugs Ara-C and 5-FU and a mean diameter less than 100 nm [5]. The drugs are used in the anticancer multidrug therapy F-MACHOP (fluorouracil, methotrexate, Ara-C, cyclophosphamide, doxorubicin, vincristine, and prednisone).…”

Section: Introductionmentioning

confidence: 99%

Influence of some physical properties of 5-fluorouracil on encapsulation efficiency in liposomes

Pentak

Sułkowski

Sułkowska

2011

J Therm Anal Calorim

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The aim of this study is to encapsulate two drugs: 5-fluorouracil (5-FU) with the hydrophobic properties and 1-b-D-arabinofuranosylcytosine (Ara-C) with the amphiphilic properties into liposomes prepared by the modified reverse-phase evaporation method (mREV) from L-a-phosphatidylcholine dipalmitoyl (DPPC). We studied the thermotropic phase behavior of liposome entrapped 5-FU and Ara-C. It is known that the stability of liposomes depends not only on the method of chemical gradient loading, the use of membrane stabilizer such as sterols, but also on the phase transition temperature (T c ) of phospholipids, which undergoes an alteration after encapsulation of drugs to liposomes. The competition of these two drugs entrapped in liposomes was analyzed by the use of two spectroscopies: 1 H NMR and UV on the basis of the analysis of the signals of each drug in the liposome-drug system. The percent of encapsulation in DPPC/Ara-C/5-FU liposome obtained by the use of UV spectroscopy amounted 93.84 and 96.05% for 5-FU and Ara-C, respectively. Phase transition temperature T c of liposomes containing Ara-C did not significantly change while for the liposomes containing 5-FU it increased in comparison with T c of the reference liposomes formed from DPPC.

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“…Important to note, their relatively large hydrated head groups enable PC lipids, in singlecomponent membranes, to order into solid bilayers of differing molecular areas [by about 10% (19)], such as ripple (P β′ ) and tilt ("gel" or L β′ ) phases (19,(28)(29)(30)(31).…”

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confidence: 99%

Large effect of membrane tension on the fluid–solid phase transitions of two-component phosphatidylcholine vesicles

Chen¹,

Santore

2013

Proc. Natl. Acad. Sci. U.S.A.

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Model phospholipid membranes and vesicles have long provided insight into the nature of confined materials and membranes while also providing a platform for drug delivery. The rich thermodynamic behavior and interesting domain shapes in these membranes have previously been mapped in extensive studies that vary temperature and composition; however, the thermodynamic impact of tension on bilayers has been restricted to recent reports of subtly reduced fluidfluid transition temperatures. In two-component phosphatidylcholine unilamellar vesicles [1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)], we report a dramatic influence of tension on the fluid-solid transition and resulting phases: At fixed composition, systematic variations in tension produce differently shaped solid domains (striped or irregular hexagons), shift fluid-solid transition temperatures, and produce a triple-point-like intersection of coexistence curves at elevated tensions, about 3 mN/m for 30% DOPC/70% DPPC. Tension therefore represents a potential switch of microstructure in responsive engineered materials; it is an important morphology-determining variable in confined systems, and, in biological membranes, it may provide a means to regulate dynamic structure.ripple tilt bilayer | phase diagram | domain morphology | biomimetic membrane | phase separation P hospholipid vesicles, capsular lamellar assemblies of phospholipid amphiphiles, are model systems that have advanced our perceptions of material surfaces and thin films, facilitated drug delivery technologies, and anchored the understanding of biological membranes to fundamental physics. Extensive studies of phase transitions in phospholipid bilayers and vesicles have focused almost exclusively on temperature and composition, revealing complex phase behavior (1-6) and beautiful patterns in the domain shapes within vesicle membranes (4, 6, 7). Tension has been mostly neglected as a thermodynamic variable and is unspecified in phase diagrams of vesicle membranes, although in analogous studies of phospholipid monolayers, surface pressure is known to drive transitions between gas-like layers, liquid fluids, and ordered crystals, which are sometimes polymorphic (8-10). Besides its fundamental thermodynamic importance, membrane tension may be biologically important, because stresses on cells can dominate their interactions (11-14) and fates (15). Indeed, tension has been proposed to regulate the dynamic structure of the cellular surface, for instance through coupling with curvature (16) or by clustering proteins in "rafts" (17, 18).Used as a mechanical variable, tension can stretch or bend uniform bilayers (19,20). In multicomponent vesicles containing coexisting fluid domains, coupling of line tension with membrane bending determines vesicle shapes and drives budding transitions (21-24). Tension has also been hypothesized, but not confirmed, to influence the shapes of solid domains (25). Relevant to the current focus on the thermodynamic role of t...

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Calorimetric and EPR studies of the thermotropic phase behavior of phospholipid membranes

Cited by 24 publications

References 40 publications

Design of liposomes containing photopolymerizable phospholipids for triggered release of contents

Design of liposomes containing photopolymerizable phospholipids for triggered release of contents

Influence of some physical properties of 5-fluorouracil on encapsulation efficiency in liposomes

Large effect of membrane tension on the fluid–solid phase transitions of two-component phosphatidylcholine vesicles

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