Theory of self-assembly of hydrocarbon amphiphiles into micelles and bilayers

Israelachvili, Jacob N.; Mitchell, D. J.; Ninham, Barry W.

doi:10.1039/f29767201525

Cited by 4,986 publications

(4,307 citation statements)

References 5 publications

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“…The ability of surfactant molecules to give the necessary curvature of the interfacial film required to form fine emulsions or microemulsions has been related to the packing geometry, which is the ratio between hydrocarbon volume, optimum head group area and tail length [14] of the molecule at the interface. Lecithin has a packing parameter around 0.8 [15] and this value is further increased if the oil phase penetrates into the alkyl chains of the lecithin molecule [16].…”

Section: Resultsmentioning

confidence: 99%

Stability of drug-carrier emulsions containing phosphatidylcholine mixtures

Trotta

Pattarino²,

Ignoni

2002

European Journal of Pharmaceutics and Biopharmaceutics

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Lipid emulsion particles containing 10% of medium chain triglycerides were prepared using 2% w/w of a mixture 1:1 w/w of purified soya phosphatidylcholine and 2-hexanoyl phosphatidylcholine as emulsifier mixture, for use as drug carriers. The mean droplet sizes of emulsions, prepared using an Ultra Turrax or a high-pressure homogenizer, were about 288 and 158 nm, respectively, compared with 380 and 268 nm for emulsions containing lecithin, or 325 and 240 nm for those containing 6-phosphatidylcholine. The stability of the emulsions, determined by monitoring the decrease of a lipophilic marker at a specified level within the emulsion, and observing coalescence over time, was also greatly increased using the emulsifier mixture. The emulsion stability did not notably change in the presence of a model destabilizing drug, indomethacin. The use of a second hydrophilic surfactant to adjust the packing properties of the lecithin at the oil-water interface provided an increase in the stability of lipid emulsions, and this may be of importance in the formulation of drug delivery systems. q

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Section: Resultsmentioning

confidence: 99%

Stability of drug-carrier emulsions containing phosphatidylcholine mixtures

Trotta

Pattarino²,

Ignoni

2002

European Journal of Pharmaceutics and Biopharmaceutics

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“…42 The surface curvature of the expected mesophase increases from lamellar to rod or spherical as the g value decreases. The molecular design of alkylsiloxane precursors having a large oligomeric siloxane unit instead of a single ¶Si(OR) 3 group is expected to lead to mesostructures with higher curvatures due to the increase of the head group area that reduces the g value.…”

Section: Other Hybrid Mesostructures Obtained By Molecular Designmentioning

confidence: 98%

Designed synthesis of nanostructured siloxane–organic hybrids from amphiphilic silicon-based precursors

2006

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This paper reports on recent progress in the synthesis of nanostructured siloxane-organic hybrids based on the self-assembly of amphiphilic silicon-based precursors. A variety of ordered hybrid materials have been obtained by molecular design of the precursors. Alkoxysilanes and chlorosilanes with covalently attached hydrophobic organic tails are hydrolyzed to form amphiphilic molecules containing silanol groups, leading to the formation of layered (lamellar) structures. Transparent and oriented thin films of lamellar hybrids were prepared by the reaction in the presence of tetraalkoxysilane. In addition, the design of molecules having alkyl chains and large oligosiloxane heads led to the formation of mesophases consisting of cylindrical assemblies, providing a direct pathway to ordered porous silica. The synthesis, structural features, and formation processes of these hybrid mesostructures are discussed.

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“…The mechanism behind these effects could lie directly on the fact that the mixed surfactants are self-assembled into vesicles and not micelles. The critical packing parameter (CPP) of a surfactant can be defined as the ratio between the cross-section area of the hydrophobic chains and optimal headgroup area at the interface [58,59]. The CPP concept is a simple and convenient way to rationalize and predict the aggregation behavior of a surfactant in a given set of conditions.…”

Section: Hemolytic Activitymentioning

confidence: 99%

Physicochemical and toxicological properties of novel amino acid-based amphiphiles and their spontaneously formed catanionic vesicles

Brito

Marques

Silva

et al. 2009

Colloids and Surfaces B: Biointerfaces

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a b s t r a c tThe design of efficient liposomal systems for drug delivery is of considerable biomedical interest. In this context, vesicles prepared from cationic/anionic surfactants may offer several advantages, mainly due to their spontaneity in formation and long-term stability. There is also an impending need to produce less toxic, more biocompatible amphiphiles, while maintaining the desirable aggregation properties. In this work, we present data for acute toxicity to Daphnia magna (IC 50 ), and potential ocular irritation (HC 50 ) for some newly prepared ionic surfactants with dodecyl chains, derived from the amino acids tyrosine (Tyr), serine (Ser), hydroxyproline (Hyp) and lysine (Lys). The micellization behavior of the compounds, evaluated from surface tension measurements, is presented and compared to more conventional ionic amphiphiles. Two types of spontaneouly formed catanionic vesicles, composed either by a dodecyltrimethylammonium bromide (DTAB)/Lys-derivative and or Ser-/Lys-derivative mixture, have also been tested for their ecotoxicity and hemolytic potential. All the micelle-forming surfactants as well as the vesicle-containing mixtures are found to have lower ecotoxicity than the reference surfactant DTAB. Moreover, the results from hemolysis and hemoglobin denaturation tests show that the Tyr-and Lys-derivatives are moderately irritant, whereas the Hyp-and Ser-ones are just slightly irritant. Even more significantly, the vesicle-containing mixtures exhibit lower hemolytic activity than the neat surfactants, a positive result for their potential use in liposomal formulations.

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Theory of self-assembly of hydrocarbon amphiphiles into micelles and bilayers

Cited by 4,986 publications

References 5 publications

Stability of drug-carrier emulsions containing phosphatidylcholine mixtures

Stability of drug-carrier emulsions containing phosphatidylcholine mixtures

Designed synthesis of nanostructured siloxane–organic hybrids from amphiphilic silicon-based precursors

Physicochemical and toxicological properties of novel amino acid-based amphiphiles and their spontaneously formed catanionic vesicles

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