Disintegration of Liposomes by Surfactants: Mechanism of Protein and Cholesterol Effects (original) (raw)
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Mechanisms of Solubilization of Mixed Liposomes: Preferential Dissolution of Liposome Components
Industrial & Engineering Chemistry Research, 2005
The mechanism of vesicle-to-micelle transformation due to the interactions with sodium dodecylsulfate (SDS) has been studied by monitoring changes in the optical density, surface tension, SDS monomer concentrations, pyrene fluorescence, and mass spectrometry. Two inflection points appeared on the optical density as well as effective hydrodynamic diameter curves. Based on the results of the surface tension and SDS monomer measurements, the first inflection point is attributed to the saturation of bilayers by SDS monomers and the onset of liposome solubilization processes. The second inflection point corresponds to the onset of complete disruption of bilayers and the critical micelle concentration of the mixed systems. The fluorescence results show the core of the mixed micelles to be more hydrophobic than that of the SDS micelles, suggesting that liposome solubilization is a micellization process. From the individual phospholipid liposome solubilization studies, it was found that phosphatidic acid (PA) molecules are more susceptible toward SDS. Interestingly, it has been detected from the mass spectra that the disruption of liposome bilayers is a preferential dissolution process. It is proposed that, at low SDS concentration, PA molecules preferentially exit first from the mixed liposome bilayers (1:1 PA/phosphatidylcholine), causing liposome solubilization. In contrast, at high SDS concentrations, the breakdown of liposome takes place instantaneously.
Physico?chemical modifications of liposome structures through interaction with surfactantsy
International Journal of Cosmetic Science, 1992
The liposome-surfactant interaction has been studied in this paper through the disrupting effect caused by surfactant molecules on large unilamellar vesicles prepared by reverse-phase evaporation. This process leads, in the end, to the rupture of such structures and to the solubilization of the phospholipidic components, via mixed surfactant-phospholipid micelle formation. This phenomenon is described by a three-stage model and characterized by two parameters: the highest surfactantlphospholipid ratio that can exist in a vesicle (Re=,) and the lowest surfactant/phospholipid ratio required to keep the lipid and surfactant in the form of mixed micelles (Resol). These parameters have been determined by spectrophotometry and 31P NMR spectroscopy, obtaining results in a good agreement with both techniques. The surfactants tested have been: sodium dodecyl sulfate (SDS), sodium laurylether sulfate (SLES), N-hexadecyl-trimethylammonium bromide (HTAB), octylphenol series (8-20 EO) and alkylbetaines (C-10, C-12 and C-14). Different Re,, and Re,, values have been obtained for each of the surfactants. This has permitted a study of the solubilizing capacity versus the phospholipidic bilayer of the different surfactants as a function of their structure. RCsumC L'interaction liposome-tensioactif a t t t ttudite moyennant I'effet cause par les molecules des tensioactifs sur des vtsicules grandes et unilamellaires prtpartes par la mtthode d'tvaporation en phase reverse. Le procts a m h e finalement ri la rupture des liposomes et A la solubilisation des composants phospholipidiques par la formation de micelles mixtes tensioactif-phospholipide. Ce phtnomtne est dtcrit par un modtle en trois ttages et caracttrist par deux paramttres: la plus haute relation tensioactif-phospholipide qui peut exister dans une vtsicule (Re=,) et la plus basse relation tensioactif-phospholipide requise pour solubiliser le lipide en micelles mixtes (ReWl). Ces paramttres ont t t t dttermints par spectrophotometrie et spectroscopie de RMN de P3', obtenant de rtsultats concordants avec les deux techniques. Les tensioactifs essayts ont t t t les suivants: dodecyl sulphate de sodium (SDS), laurylether sulphate de sodium (SLES), bromure de N-hexadecyltrimethylammonium (HTAB), une serie d'octylphenols (8-20 EO) et alkylbetaines (C-10, C-12 and C-14). On a obtenu difftrents valeurs de Re,, et de Re,, pour chacun des tensioactifs essayts. Ce fait a permis I'ttude de la capacite de solubilisation des difftrents tensioactifs face a des liposomes en fonction de la structure de ces tensioactifs.
Mechanism of mixed liposome solubilization in the presence of sodium dodecyl sulfate
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2001
Structural transformations of vesicles to micelles that take place during the interaction of sodium dodecyl sulfate (SOS) with individual and mixed vesicles of phosphatidyl choline (PC) and phosphatidic acid (FA), have been studied by monitoring changes in optical density and in the concentration of free SOS monomer in the respective systems. Incorporation of the surfactant monomers (SOS) in the bilayers was found to result in an initial increase in concentration of the mixed vesicles up to its saturation. Subsequently a progressive relaxation of these structures together with a simultaneous fonnation of mixed micelles was found to occur. The breakup of bilayer and the fonnation of mixed micelles were completely dependent on the structure of the individual phospholipid. The solubilization of the anionic phosphatidic acid vesicle was very fast in the presence of SOS, due to its simple structure and its compatibility with the SOS molecule. But solubilization of the zwitter ionic phosphatidyl choline vesicle was very complicated in the presence of SOS, possibly due to its complex structure and the zwitterionic nature. On the other hand, solubilization of the mixed vesicle (mixed liposome) and fonnation of mixed micelle was found to be relatively easier. This may be attributed to one of the phospholipid component preferentially coming out first through interaction with SOS, thereby making the overall system unstable and enhancing the micellization processes. 0 200 I Elsevier Science B. V. All rights reserved. studying solubilization of cell membranes [4-7] and surfactants interactions with such biosystems as skin. The interaction of surfactants with liposomes eventually leads to the rupture of its vesicle structure resulting in the solubilization of phospholipid components. In general, there is agreement that growth of vesicles occurs in the initial stages, followed by the formation of a number'of complex lipid-surfactant aggregates associated with the vesicle to micelle transformations. The interactions of sodium dodecyl sulfate (SDS) with
Chemistry and Physics of Lipids, 2011
The cationic large unilamellar mixed liposomes from 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and didodecyldimethylammonium bromide (DDAB) or dioctadecyldimethylammonium bromide (DODAB) were prepared. The influence of the addition of Triton X-100 (TX-100) or octaethylene glycol mono-n-dodecylether (C12E8) on the membrane integrity was investigated turbidimetrically. The stability of the liposomal systems was estimated by monitoring fluorimetrically at 25 °C the rate of spontaneous and surfactant-induced release of entrapped 5(6)-carboxyfluorescein (CF). In order to evaluate the interaction of the cationic DODAB guest with the host POPC membrane, the main phase transition temperatures (Tm) were determined by electron paramagnetic resonance spectroscopy (EPR). All the results obtained show that the presence of DODAB and DDAB stabilizes the POPC liposomes. The extent of stabilization depends on the concentration and nature of the cationic guest.► The kinetic stability of cationic mixed liposomes was investigated fluorimetrically. ► Rate constants for spontaneous and induced breakdown of liposomes have been obtained. ► EPR has been used to monitor the molecular dynamics of liposomal membranes. ► The insertion into the bilayer of the cationic guest enhances liposome stability. ► The stabilization depends on the concentration and nature of the cationic guest.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1983
The disintegration behaviour of liposomes in polyoxyethylene lauryl ether (PLE) and sodium cholate solutions was studied by the turbidity disappearance method, in maximally solubilized systems of liposomes, the molar ratios (phosphatidyicholine/sudactant) were 0.43 and 1.8 for PLE and sodium cholate, respectively. The disintegration process of either unilamellar or multilameilar liposomes followed first-order kinetics. Based on a physical model in which liposomes heterogeneous in size were assumed to disintegrate from the outermost shell one by one, a mathematical expression of the turbidity disappearance rate was introduced and applied to explain the data thus obtained. Model calculations suggested that the number of disintegrated shells would not be so large, even if up to 50% reduction of the initial turbidity was observed. From the dependence of the pseudo-first-order rate constant (kob S) on the surfactant concentration for unilamellar liposomes, it was assumed in general that kob S consists of the contributions of the monomer and micellar fractions: for PLE, both fractions shared in the disintegration, but only the micellar fraction with sodium cholate. Furthermore, in the latter case, kob ~ depended on the initial liposome concentration. These results are likely to be consistent with the proposed modes of sudactant action classified as type A and type B (Helenius, A. and Simons, K. (1975) Biochim. Biophys. Acta 415, 29-79).
Biochemistry, 1988
The mechanisms governing the solubilization by Triton X-100, octyl glucoside, and sodium cholate of large unilamellar liposomes prepared by reverse-phase evaporation were investigated. The solubilization process is described by the three-stage model previously proposed for these detergents [Lichtenberg, D., Robson, R. J., & Dennis, E. A. (1983) Biochim. Biophys. Acta 737,285-3041. In stage I, detergent monomers are incorporated into the phospholipid bilayers until they saturate the liposomes. At that point, i.e., stage
The Journal of Physical Chemistry C, 2017
α-zein, a storage protein in corn endosperm, could be purified easily and in large amounts. In this study, α-zein was incorporated into phospholipid-cholesterol (PC-Chol) liposomes. The maximal amount of α-zein incorporated in the liposome was 0.05% (mol/mol) and the PC/Zein molar ratio was near 2400. At this level of the zein insertion, the phase transition temperature of the lipid bilayer was little affected, but the leakage of doxorubicin (DOX) from the PC-Chol liposome became slower obviously when α-zein was added at a higher temperature than the phase transition temperature. Cryogenic transmission electron micrographs of the PC-Chol-Zein liposome showed that adjacent membranes in multilamellar vesicles were often aligned at a regular interval of about 7 nm. Data from synchrotron small angle X-ray scattering of the PC-Chol-Zein liposome indicated the formation of the multilamellar structure with an inter-membrane interval of 7.2 nm, whereas no homogenous membrane alignment was observed in the absence of zein. The present observation can be well explained by supposing that α-zein takes such an elongated conformation that it penetrates through two adjacent membrane layers. This feature seems to be compatible with a recently proposed super helical structural model of α-zein. Meanwhile, experiments with the fluorescent labelled α-zein showed that the PC-Chol-Zein liposome could be uptaken by an intact cell and localized in some specialized area (possibly endosomes) within the cell instead of diffuse distribution in the cell. Thus the PC-Chol-Zein liposome seems to act as an interesting biomembrane model and may be applicable as a drug delivery system.
Chemical and Pharmaceutical Bulletin, 2012
We have investigated the effects of two bile salts, chenodeoxycholate (CDC) and ursodeoxycholate (UDC), and a widely used detergent, Triton X-100 (T X-100), on normal and poly(ethylene glycol)-modified liposomes (PEGylated liposomes). We tested various lipid compositions, including hydrogenated soybean phosphatidylcholine/cholesterol/PEG-conjugated lipid (HSPC/PEG-lipid). Alterations in permeability were determined by the rate of drug release from the liposomes and solubilization was assessed by measuring the particle size of liposomes. In addition, we attempted to observe interactions between the detergents and lipid bilayers by using surface plasmon resonance (SPR). CDC induced drug release from liposomes in a dose-dependent manner, and the PEGylated liposomes tended to be susceptible to CDC. While UDC did not strongly induce drug release from liposomes, UDC exhibited a similar tendency with CDC. In case of T X-100 , there were significant differences in the percentage of released drug between normal and PEGylated liposomes, and the percentage of T X-100-induced drug release further increased with an increased ratio of PEG-lipid. SPR analysis revealed that the lipid bilayer including PEG-lipid was selectively solubilized by T X-100 , correlating with the drug release data. These results suggest that the effect of detergents on the lipid bilayer of liposomes depends on both the kind of detergent and the lipid composition, including the presence or absence of PEG-lipid. Moreover, the effects of T X-100 on the lipid bilayers of the PEGylated liposomes significantly differed from those on the lipid bilayers of the normal liposomes.
Integrity of liposomes in presence of cyclodextrins: Effect of liposome type and lipid composition
International Journal of Pharmaceutics, 2007
Liposome stability during incubation in presence of cyclodextrins (CDs) is studied. Dried-rehydrated vesicle (DRV), multilamellar vesicle (MLV) and small unilamellar vesicle (SUV) calcein-encapsulating liposomes, composed of different lipids are formulated, and retention of calcein is followed during vesicle incubation in hydroxypropyl--CD (HP-CD), HP␥-CD or methyl--CD (Me-CD), for 24 h. Results demonstrate that liposome integrity in cyclodextrins is affected by lipid composition and type. For the same lipid composition calcein release from vesicles is faster in the order: MLV > DRV > SUV. Me-CD influences liposome stability most, compared to the other CD's studied. Vesicles composed of saturated phospholipids were found more stable compared to phosphatidyl-choline (PC) liposomes, suggesting that phospholipid saturation and membrane rigidity influences the interaction between liposomal-lipids and CD molecules. Chol (cholesterol) addition in lipid membrane improves PC-liposome integrity, but has opposite or no effect on liposomes consisting of saturated lipids. Decrease of vesicle dispersion turbidity and size distribution in presence of CD, implies that Me-CD induces vesicle disruption and solubilization (to micelles). Turbidity measurements confirm that DRV liposomes are affected more than SUV.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1998
The interaction of a series of alkylbetaines (alkyl chain lengths C-10 (Clo-Bet), C-12 (C12-Bet) and C-14 (C14-Bet)) with liposomes modelling the stratum corneum (SC) lipid composition (40% ceramides, 25% cholesterol, 25% palmitic acid and 10% cholesteryl sulphate) was investigated. The surfactant/lipid molar ratios Re and the bilayer/aqueous phase partition coefficients K were determined by monitoring the changes in the static light scattering of the system during solubilization. The fact that the free concentration for solubilization by each surfactant tested was always similar to its critical micelle concentration (CMC) indicates that the liposome solubilization was mainly ruled by the formation of mixed micelles. The K parameter rose as the surfactant alkyl chain length increased or its CMC decreased, whereas the Re parameter showed a minimum for C12-Bet. Thus, although the highest ability to saturate or solubilize SC liposomes corresponded to the C12-Bet, the highest degree of partitioning into liposomes (or affinity with these bilayer structures) was reached for Cx4-Bet. The overall balance of these two tendencies shows that C~2-Bet had the highest activity at the two interaction levels investigated in terms of the total surfactant amount needed to produce these effects. Different trends in the interaction of these surfactants with SC liposomes were observed when comparing the Re and K parameters with those reported for phosphatidylcholine. Thus, whereas SC liposomes were more resistant to the surfactant action (especially for Clo-Bet), the affinity of these surfactants with these bilayer structures was higher in all cases.