Aggregate Structure in Dilute Aqueous Dispersions of Oleic Acid/Sodium Oleate and Oleic Acid/Sodium Oleate/Egg Phosphatidylcholine

Edwards, Katarina; Silvander, Mats; Karlsson, Goeran

doi:10.1021/la00007a020

Cited by 87 publications

(83 citation statements)

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“…6,7) Oleic acid vesicles can spontaneously form at the pH range of 7.5-9.0. 5,8,17) Luisi et al reported that the turbidity change in the presence of preformed vesicles was extremely faster than the formation of pure oleic acid vesicles. The formation of pure oleic acid vesicles reached to equilibrium by taking several days while the presence of preformed oleate or POPC vesicles could accelerate vesicle formation to rapidly reach a plateau.…”

Section: Discussionmentioning

confidence: 99%

“…[1][2][3][4] Fatty acids are one kind of surfactants whose properties are different from the others, that is, the fatty acids exist as micellar form above pH 9 but they can spontaneously form vesicles in the appropriate conditions. [5][6][7][8][9] Luisi et al have made interesting reports using dynamic light scattering, freeze fracture electron microscopy and cryotransmission electron microscopy as follows: when sodium oleate micellar solution was added into suspension of preformed oleate vesicles or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles, the size of newly formed vesicles was similar to that of the preformed vesicles and preformed vesicles remarkably expedited the rate of new vesicles organization.10-13) They called this phenomenon "matrix effect". However, normally average vesicular size in matrix effect was close to the size of preformed vesicles as far as the sizes were evaluated by quasielastic light scattering, which leading us to some misunderstanding of size distribution of newly formed vesicles.…”

mentioning

confidence: 99%

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Size Control of Mixed Egg Yolk Phosphatidylcholine (EggPC)/Oleate Vesicles

Chungcharoenwattana

Ueno

2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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Incorporation of surfactants into vesicles lead to structural change of the vesicles followed by vesicle-to-micelle transition. The studies on this process have contributed to size regulation of vesicles prepared by removing detergent from detergent-phospholipid mixed micelles. [1][2][3][4] Fatty acids are one kind of surfactants whose properties are different from the others, that is, the fatty acids exist as micellar form above pH 9 but they can spontaneously form vesicles in the appropriate conditions. [5][6][7][8][9] Luisi et al. have made interesting reports using dynamic light scattering, freeze fracture electron microscopy and cryotransmission electron microscopy as follows: when sodium oleate micellar solution was added into suspension of preformed oleate vesicles or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles, the size of newly formed vesicles was similar to that of the preformed vesicles and preformed vesicles remarkably expedited the rate of new vesicles organization.10-13) They called this phenomenon "matrix effect". However, normally average vesicular size in matrix effect was close to the size of preformed vesicles as far as the sizes were evaluated by quasielastic light scattering, which leading us to some misunderstanding of size distribution of newly formed vesicles.To obtain more precise information relating size distribution with easier techniques, we started to study on this effect by the combination of gel filtration chromatography/quasielastic light scattering and found that the technique could provide more detailed insight into size distribution of newly formed vesicles without misapprehension as detection with mere dynamic light scattering technique. The study of this report deals with the effect of size variation of preformed vesicles as well as the influence of molar ratios EggPC/oleate on the size distribution of newly formed vesicles. Oleate solution was added to preformed egg yolk phosphatidylcholine vesicles with two original sizes followed by gel filtration on Sephacryl S-1000. The size of the vesicles and phospholipid and oleate concentrations of each fraction after gel filtration were analyzed. The results showed the final size distribution was somewhat dependent on the former vesicular size. ExperimentalMaterials Egg yolk phosphatidylcholine (EggPC; purity of PCϭ98.8%) was purchased from Nihon Yushi (Tokyo, Japan). Oleic acid sodium salt (98%), boric acid (99.5%), sodium chloride and calcein were purchased from Nacalai Tesque (Kyoto, Japan). All these materials were used without further purification. Methods. Preparation of Liposomal SuspensionLiposomes were prepared by the extrusion method as described below. A desired amount of phospholipids was dissolved in chloroform/methanol (2 : 1, v/v) mixture, dried into a thin film on the wall of a glass tube under a stream of nitrogen. The remaining solvent was then removed under reduced pressure for more than 6 h. The lipids were then resuspended in a borate buffer solution (0.15 M NaCl, 0.1 M borate, pH 8.5) cont...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Size Control of Mixed Egg Yolk Phosphatidylcholine (EggPC)/Oleate Vesicles

Chungcharoenwattana

Ueno

2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…11,16,20,26 There are two methods for constructing macroscopic tubular, cylindrical, or helical assemblies of oleates. One method is similar to that used in the formation of myelin figures of phosphatidylcholine.…”

Section: Growth Of Oleate Assemblies By the Addition Ofmentioning

confidence: 99%

Structure and growth behavior of centimeter-sized helical oleate assemblies formed with assistance of medium-length carboxylic acids

et al. 2015

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The nonequilibrium organization of self-assemblies from small building-block molecules offers an attractive and essential means to develop advanced functional materials and to understand the intrinsic nature of life systems. Fatty acids are well-known amphiphiles that form self-assemblies of several shapes. Here, we found that the lengths of helical structures of oleic acid formed in a buffered aqueous solution are dramatically different by the presence or absence of certain amphiphilic carboxylic acids. For example, under the coexistence of a small amount of N-decanoyl-L-alanine, we observed the formation of over 1-centimeter-long helical assemblies of oleate with a regular pitch and radius, whereas mainly less than 100 µm-long helices formed without this additive.Such long helical assemblies are unique in terms of their highly dimensional helical structure and growth dynamics. Results from the real-time observation of self-assembly formation, site-selective small-angle X-ray scattering, high-performance liquid chromatography analysis, and pH titration experiments suggested that the coexisting carboxylates assist in elongation by supplying oleate molecules to a scaffold for oleate helical assembly.

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“…According to Edwards et al, the apparent pK a of fatty acid is shifted to considerably higher values when it is incorporated into a micelle or an aggregate. 12) Thus, the number of sites available for the DOX-oleate electrostatic interaction should be additionally decreased due to a partial reprotonation of assembled oleates. This is confirmed by the free drug reappearance at Rϭ20 (Fig.…”

Section: Liquid-liquid Extraction Of Dox In Presence Of Oleate Ionsmentioning

confidence: 99%

“…Moreover, oleates are non-toxic and the behavior of oleic acid and its ion (oleate, OA Ϫ ) in aqueous solution is rather well studied. [12][13][14][15] Fluorescence spectroscopy has been successfully used to study interactions between DOX and its surrounding, for instance when the drug intercalates DNA 16,17) or penetrates within membrane models or liposomal drug carriers. 18,19) Indeed, the dihydroanthraquinone moiety of DOX is a well known fluorophore excitable with visible light (absorption maxima at 480-500 nm).…”

mentioning

confidence: 99%

On the Interaction of Doxorubicin with Oleate Ions: Fluorescence Spectroscopy and Liquid-Liquid Extraction Study

Munnier

Tewes

Cohen-Jonathan

et al. 2007

CHEMICAL & PHARMACEUTICAL BULLETIN

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Doxorubicin (DOX) is an antineoplastic agent of the anthracycline family used as a first-line treatment in numerous neoplastic diseases, particularly in breast cancer.1) The progression of tumor cell resistance, in particular multidrug resistance (MDR), is one of the main factors which limit its employment.2) MDR is generally associated with a decreased intracellular accumulation of drug related to a membrane glycoprotein, the P-gp that contributes to a rapid expelling of the drug from the cell.3) An interesting way to overcome this active efflux would be to support the drug accumulation into the cell, in particular by increasing its capacity to cross lipidic membranes. One can act upon the membrane fluidity or act upon the hydrophilic/lipophilic properties of the drug.DOX molecule (see structure on Fig. 1) is considered hydrophilic at physiological pH because it presents a positive charge on the sugar moiety. The more lipophilic molecular form of DOX is dominant at moderately alkaline pHs, between 8.2 and 9.5, the pK a values of the amine and the phenol in position 11 respectively.4) The hydrophilicity of DOX is also depending on the drug concentration, since beyond a concentration of 30 mM DOX molecules are prone to form less hydrophilic dimmers (stacking effect) which precipitate in aqueous solution. The increase of the pH, i.e. of the neutral form percentage, is in favor of the stacking phenomenon. 5,6) It has been recently shown that lipophilicity of cationic drugs 7,8) can be increased by association with an anion, namely with a long chain ion of a fatty acid.9,10) Nevertheless, no study is devoted to the molecular interaction between the drug and the ion. On the other hand, combined use of an anticancer drug, paclitaxel, with different fatty acids, has been shown to enhance mortality of cancer cells in vitro.11) It has not yet been established whether this gain in efficacy is dependent on an assembly between the drug and the fatty acid ion.Association DOX-fatty acid could be more lipophilic than DOX alone, and enter more efficiently into the cell. It could also facilitate drug encapsulation into pharmaceutical formulations based on hydrophobic polymers or liposomes. 7,9) Oleic acid is a good candidate for such an association within a feasibility study: it is the simplest of the w-9 fatty acid family (Fig. 1), and possesses a long hydrophobic chain that could contribute to a gain of lipophilicity of the association. Moreover, oleates are non-toxic and the behavior of oleic acid and its ion (oleate, OA Ϫ ) in aqueous solution is rather well studied. [12][13][14][15] Fluorescence spectroscopy has been successfully used to study interactions between DOX and its surrounding, for instance when the drug intercalates DNA 16,17) or penetrates within membrane models or liposomal drug carriers. 18,19) Indeed, the dihydroanthraquinone moiety of DOX is a well known fluorophore excitable with visible light (absorption maxima at 480-500 nm). Fluorescence spectroscopy Increase of lipophilicity of cationic doxorubicin (DO...

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Aggregate Structure in Dilute Aqueous Dispersions of Oleic Acid/Sodium Oleate and Oleic Acid/Sodium Oleate/Egg Phosphatidylcholine

Cited by 87 publications

References 2 publications

Size Control of Mixed Egg Yolk Phosphatidylcholine (EggPC)/Oleate Vesicles

Size Control of Mixed Egg Yolk Phosphatidylcholine (EggPC)/Oleate Vesicles

Structure and growth behavior of centimeter-sized helical oleate assemblies formed with assistance of medium-length carboxylic acids

On the Interaction of Doxorubicin with Oleate Ions: Fluorescence Spectroscopy and Liquid-Liquid Extraction Study

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