Surface properties of cholesterol-containing membranes detected by Prodan fluorescence

Krasnowska, Ewa K.; Bagatolli, Luís A.; Gratton, Enrico; Parasassi, Tiziana

doi:10.1016/s0005-2736(01)00286-3

Cited by 55 publications

(54 citation statements)

References 24 publications

(30 reference statements)

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“…Such a two-step change was also seen in the GP value and is expected to result from the change in the vertical location of Prodan molecules with the thermotropic phase transition of liposome membrane; that is, the pretransition from the L β′ to the P β′ phase and the main transition from the P β′ to the L α phase. 23) We found that the lower and higher temperatures for abrupt changes in λ max or GP value of Prodan are close to those in DSC thermograms showing the pre-and main transitions at 47.8°C and 53.6°C, respectively (Fig. 1A).…”

Section: Dsc Measurements For Hspc-cholesterol Binary Liposome Membranesupporting

confidence: 74%

Thermotropic Phase Behavior of Hydrogenated Soybean Phosphatidylcholine–Cholesterol Binary Liposome Membrane

Kitayama

Takechi

Tamai

et al. 2014

CHEMICAL & PHARMACEUTICAL BULLETIN

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By combination of differential scanning calorimetry (DSC) and fluorescence spectroscopy of 6-propionyl-2-(dimethylamino)naphthalene (Prodan), we elucidated the thermotropic phase behavior of hydrogenated soybean phosphatidylcholine (HSPC)-cholesterol binary liposome membrane which has similar lipid composition to Doxil ® , the widely used liposome product in treatment of various tumors. We found that the characteristic points at cholesterol mole fraction (X ch ) 0.023 and 0.077 correspond to the hexagonal lattice, in which cholesterol molecules are considered to be regularly distributed in all regions of HSPC lipid bilayer with 1 : 42 and 1 : 12 units, respectively, as static averaged structures. Apparent endothermic peak disappeared at X ch 0.40 in the DSC thermograms, indicating the existence of single liquid ordered phase at X ch >0.40. In addition, fluorescence measurements of Prodan and its lauroyl derivative in poly(ethylene glycol) (PEG)-modified liposomes indicated that PEG modification has a negligible effect on the phase behavior of HSPC-cholesterol binary liposome membrane. These results may provide useful information in developing novel liposome products whose stability and encapsulated drug release are controlled.Key words liposome; cholesterol; phase diagram; differential scanning calorimetry; Prodan Liposomes are used as drug delivery systems because of their high biocompatibility and ability to encapsulate a large amount of pharmaceuticals inside the vesicle.1) Thermodynamic states of liposome membrane are considered as an important factor in terms of particle stability and encapsulated drug release. Therefore, phase transition temperatures and phase states of lipid membranes are important physicochemical index in assessing the liposomal product.Liposomes are mainly composed of phospholipids in the lamellar phase such as dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine (DSPC), and hydrogenated soybean phosphatidylcholine (HSPC). Because all these lipids have saturated fatty acids, they have relatively high phase transition temperatures 2) and therefore, are used in preparation of stable liposomes. The commercial liposomal products such as Doxil ® and AmBisome ® are composed of HSPC and cholesterol in which the incorporation of cholesterol into the lipid bilayer modulates the liposome membrane fluidity. 3,4)Poly(ethylene glycol) (PEG)-lipid is also a fundamental component in Doxil ® to extend the circulation time in plasma. In theory, HSPC and cholesterol can be either domain segregated, randomly distributed, or regularly distributed depending upon the energy function. 5) However, the relationship between the phase states of HSPC-cholesterol liposome membrane and lateral distribution of cholesterol in the membrane has not been fully elucidated. Optimal modulation of miscibility between lipid molecules is of fundamental importance to control drug release from liposomes. 6)The phase diagram for lipid mixtures shows several different regions of phase coexistence, 7) including lame...

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Section: Dsc Measurements For Hspc-cholesterol Binary Liposome Membranesupporting

confidence: 74%

Thermotropic Phase Behavior of Hydrogenated Soybean Phosphatidylcholine–Cholesterol Binary Liposome Membrane

Kitayama

Takechi

Tamai

et al. 2014

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…The two lipids DPPC and DMPC differ only in the size of the hydrocarbon chain length (14 and 16 carbon atoms, respectively) and have transition temperatures of T tr (DMPC) = 23.7 C [31] and T tr (DPPC) = 41 C. [39] They form ideal mixtures with transition temperatures intermediate between the values of the pure components. However, the addition of cholesterol increases the main transition temperature: DMPC/ CHOL vesicles have T tr = 27.6 C and DMPC/DPPC/CHOL have 40 C < T tr < 45 C. [36] This means that at 25 C the binary mixture is near its T tr , whereas the ternary mixture is well below this value, originating the difference in the viscoelastic properties reported in Table 1. Because of the similarity of the properties of the two types of liposome layers, we restricted the subsequent studies to the DMPC/CHOL vesicles.…”

Section: Qcm-d Measurementsmentioning

confidence: 99%

“…[23] The increase of both elasticity and viscosity of the liposome layer when the liposomes contain cholesterol may be explained by the effect of cholesterol on the surface packing of the phospholipid bilayer. [36,37] At physiological cholesterol concentrations (≥30 mol %), a liquid-ordered phase is present in DMPC and DPPC vesicles and the overall lipid dynamics decreases, thus implying that the lipid membrane becomes stiffer and thicker. This effect should also be responsible for the higher thickness of the cholesterol-containing liposome layers.…”

Section: Qcm-d Measurementsmentioning

confidence: 99%

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Formation of an intact liposome layer adsorbed on oxidized gold confirmed by three complementary techniques: QCM‐D, AFM and confocal fluorescence microscopy

Serro

Carapeto²,

Paiva³

et al. 2011

Surface & Interface Analysis

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Supported layers of vesicles of dimyristoyl and dipalmitoyl phosphatidylcholine (DMPC and DPPC) containing cholesterol (CHOL) are adequate models for eukaryotic plasma membranes. Among the possible substrates to support these layers, gold offers the possibility of being used as an electrode for application in sensors. However, the formation of intact liposome layers on gold is not completely understood and several authors use more or less complex strategies to bind the liposomes. In this work we investigate the adsorption of unilamellar vesicles of DMPC, DMPC/CHOL and DMPC/DPPC/CHOL on the surface of oxidized gold using a quartz crystal microbalance with dissipation, atomic force microscopy and laser scanning confocal fluorescence microscopy. The results of all techniques indicate that for lipid concentrations ≥ 0.7 mgÁmL -1 a dense layer of intact liposomes irreversibly adsorbs on the gold surface.

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“…It is also important to stress that the lipid bilayer is highly polar with structured H-bonding at the water/lipid interface, while the hydrocarbon tails have low polarity. On the basis of the fluorescence experiments the group of Krasnowska (2001) proposed that fluorescent moiety of the probe resides along lipid axis, in a way that its dimethylamonium group is interacting with the lipid head groups (Hsieh and Wu 1995). On the other hand, based on his fluorescence studies Chong (1988) proposed different alignment of PRODAN.…”

Section: Introductionmentioning

confidence: 99%

Location of PRODAN in lipid layer of HDL particle: a Raman study

et al. 2008

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FT Raman spectroscopy has been applied to determine the location of PRODAN within HDL and to investigate its influence on the structure of the particle. The complex spectra of HDL and HDL labeled with PRODAN were divided into three regions according to the wave numbers, and adherent spectra were compared separately. Additionally, recorded spectra of protein and lipid fractions of HDL were used as a support for the assignment of particular vibrations in intact particles. In high frequency region, the shift in vibrational frequencies of CH 3 groups but almost negligible shift of CH 2 groups suggests that PRODAN is situated at the water/lipid interface in the vicinity of the protein. The statement is supported by the observed influence of PRODAN on particular lipid vibrations of phospholipids head-groups.In the fingerprint region, the influence of PRODAN is observed as the slight change in -strand secondary structure of apolipoprotein and strongly reduced vibrations of the acyl chain in lipids. That additionally confirms that PRODAN mainly interacts with the lipid domain of the particle. In the low frequency region, the lack of change in Tyr Fermi resonance doublet and only slight differences in the pattern of CS and SS stretching vibrations in labeled HDL confirms that PRODAN has no influence on structure of apolipoprotein embeddd in lipid domain. The main conclusions drawn from the vibrational spectra of HDL with and without PRODAN clearly confirm that PRODAN induces negligible changes in HDL structure and hence is reliable fluorescent label for the structural analysis.

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Surface properties of cholesterol-containing membranes detected by Prodan fluorescence

Cited by 55 publications

References 24 publications

Thermotropic Phase Behavior of Hydrogenated Soybean Phosphatidylcholine–Cholesterol Binary Liposome Membrane

Thermotropic Phase Behavior of Hydrogenated Soybean Phosphatidylcholine–Cholesterol Binary Liposome Membrane

Formation of an intact liposome layer adsorbed on oxidized gold confirmed by three complementary techniques: QCM‐D, AFM and confocal fluorescence microscopy

Location of PRODAN in lipid layer of HDL particle: a Raman study

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