Thermodynamics of Demicellization of Mixed Micelles Composed of Sodium Oleate and Bile Salts

Hildebrand, Annegret; Garidel, Patrick; Neubert, Reinhard H.H.; Blume, Alfred

doi:10.1021/la035526m

Cited by 91 publications

(81 citation statements)

References 66 publications

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“…Sodium oleate concentrations went from 0 to 5 mM, knowing that the known critical micellar concentration is 0.9-2.4 mM in a 0.1 M NaCl water solution at pH 7.5 at 25°C. 20) We added respectively the appropriate volumes of DOX solution, buffer and sodium oleate solutions to obtain the desired concentrations in a 1 ml sample. The samples were prepared progressively, homogenized 10 s by vortex and immediately analyzed by fluorescence spectrometry.…”

Section: Methodsmentioning

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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Section: Methodsmentioning

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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“…The thermodynamic parameters ΔG T # and TΔS T # are calculated for the intrinsic partition coefficient P 0 and the average partition coefficient P av [41,56,62,64,65].…”

Section: Investigation Of Detergent Water To Membrane Partitioning Bymentioning

confidence: 99%

“…The isothermal titration experiments were done with a MicroCal OMEGA titration calorimeter and an MCS ITC unit (MicroCal, Inc., Northhampton, MA, USA) as described before [62,65,79]. The calorimeter sample cell volume is V = 1.368 mL.…”

Section: Isothermal Titration Calorimetry (Itc)mentioning

confidence: 99%

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

et al. 2007

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Abstract:The two main steps of the membranolytic activity of detergents: 1) the partitioning of detergent molecules in the membrane and 2) the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC) and sodium deoxycholate (NaDC) with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry). A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc). The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering).

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“…As a result, the hydrophobized fine smithsonite particles interacted with and adhered to the surface of coarse polystyrene particles when the agitation was increased up to 2000 rpm, which led to a high recovery of smithsonite. A further increase in conditioning speed (>2000 rpm) would cause detachment of the adhered ultrafine particles or disrupt the formed smithsonite-polystyrene aggregates due to the high shear forces at the contact surface [34]. …”

Section: Flotation Behaviormentioning

confidence: 99%

The Effect of Polystyrene on the Carrier Flotation of Fine Smithsonite

Zhang

Sun

et al. 2017

Minerals

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Abstract:Carrier flotation is a common technique used to improve flotation recovery of ultrafine ores. In this study, we used coarse polystyrene as the carrier material to enhance flotation recovery of fine smithsonite (ZnCO 3 ) particles. Sodium oleate was used as the collector and played a role in the adhesion of fine smithsonite to polystyrene due to its amphipathic properties. The carrier feature of polystyrene was demonstrated using particle size analysis, total organic carbon, and scanning electron microscopy. The fine smithsonite particles coated the polystyrene particles through a reaction between the active zinc sites and the carboxyl head groups of the oleate adsorbed on smithsonite and through a hydrophobic interaction between polystyrene and the hydrocarbon chains of the oleate. Newly enlarged particle aggregates with smithsonite shells enhanced collision and attachment of the hydrophobized aggregates with bubbles, which accelerated smithsonite flotation recovery.

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Thermodynamics of Demicellization of Mixed Micelles Composed of Sodium Oleate and Bile Salts

Cited by 91 publications

References 66 publications

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

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

Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

The Effect of Polystyrene on the Carrier Flotation of Fine Smithsonite

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