sorbitan-monopalmitate and sorbitan-monolaurate

A defined change in formulation components affects the physical and chemical characteristics of cationic liposomes (CLs) carriers in many ways. Therefore, a great degree of control can be exercised over the structure by modifying the CLs with various materials, leading to new innovations for carrier improvement. In the present study, surface modifications of cationic liposomes with non-ionic surfactants--sorbitan monoesters serials (Span 85, 80, 40 and 20) were carried out for developing a new gene transfer carrier. Span modified cationic liposomes (Sp-CLs) were prepared by reverse phase evaporation method (RPV) and self-assemble complexes of antisense oligonucleotides/surfactant modifying cationic liposomes were prepared by auto-coacervation through electrostatic effect. Characterization of Sp-CLs and the self-assembled complex was performed by electron microscope, particle size, zeta potential, turbidity and agarose electrophoresis. Furthermore, in vitro cellular uptake experiment showed that Span plays a role in enhancing the cellular uptake of encapsulated oligonucleotides mediated by Sp-CLs by the endocytosis-dependent route. CLs modified with Span 40 significantly facilitated the cellular uptake by COS-7 cells and HeLa cells; also showed some positive effect on gene expression. That suggests it is a potential non-viral carrier for efficient gene transfer.

Topics: Cations; Cell Line; Gene Transfer Techniques; Genetic Vectors; Green Fluorescent Proteins; HeLa Cells; Hexoses; Humans; Liposomes; Microscopy, Electron, Transmission; Nephelometry and Turbidimetry; Surface-Active Agents

Creams from three components, surfactant, purified water and oil, were prepared. Comparable molar fractions of components were used in order to better understand the structural properties of the components used. The surfactants were sorbitan monoesters, sorbitan monolaurate, monopalmitate, monostearate and monooleate, which differed from each other in the length or structure of the hydrocarbon chain. The oils used were isopropylpalmitate and myristate, and they differed from each other in the length of the fatty acid chain. Rheological properties, droplet size distributions and types (either o/w or w/o) of the creams were studied. The rheological tests used were oscillation stress sweep test, creep recovery test and viscosity test. The modelling of the creep phase was based on the creep recovery test. Sorbitan monolaurate and monostearate formed w/o creams, sorbitan monopalmitate and monooleate o/w creams. It appeared that the double-bonded structure of the surfactant made the cream less elastic. Elasticity was increased due to lengthening of the alkyl chain of the surfactant and increased amount of surfactant. Also the lengthening of the fatty acid chain of the oil made the creams more elastic. The results of the rheological tests and droplet size distributions correlated well each other. According to the modelling of the creep phase, creams could be represented either with the Burger model or with the Maxwell model.

Topics: Elasticity; Hexoses; Ointments; Rheology; Surface-Active Agents

Properties of oil-in-water emulsions containing non-ionic emulsifiers were evaluated in relation to nature of the dispersed phase, emulsifier composition and processing parameters. Particle size of mineral oil (hydrocarbons)-in-water emulsions was independent of the HLB of an optimized emulsifier blend, whereas, the particle size of olive oil (triglycerides)-in-water emulsions was the smallest at the optimum HLB of the emulsifier blend. The non-ionic emulsifiers reduced the particle size of mineral oil emulsions more efficiently than that of olive oil emulsions. Contrary to previously published reports, the nature of the dispersed phase, HLB of the emulsifier blend or the initial particle size of emulsions showed no influence on the final particle stability of the emulsions. This difference was attributed to the optimization of the emulsifier blend and processing parameters in the preparation of emulsions.

Topics: Emulsions; Excipients; Hexoses; Ions; Mineral Oil; Olive Oil; Particle Size; Plant Oils; Polysorbates; Surface-Active Agents; Water

Using the analytical constants for sorbitan monolaurate, monopalmitate, monostearate, and monooleate given in the National Formulary (NF), calculations were carried out that indicated that these emulsifiers are esters of sorbitol mono- and dianhydrides. Contrary to the NF description, no significant amount of sorbitol ester was calculated to be present, in agreement with recent experimental findings. Further calculations were made using the NF-defined analytical constants of polysorbate 20, polysorbate 40, polysorbate 60, and polysorbate 80, which indicate that these emulsifiers are esters primarily of polyoxyethylated sorbitol monoanhydride (i.e., sorbitan), with lesser quantities of polyoxyethylated esters of sorbitol dianhydride. Since all hydroxyl groups of the polysorbates are primary, random distribution of acyl groups on the available hydroxyls can be assumed, and the likely composition of these emulsifiers can be calculated. The most abundant compounds appear to be polyoxyethylated sorbitan mono-, di-, and triesters. Although the polysorbates are stated to contain 20 moles of ethylene oxide per mole of ester, the oxyethylene contents stated in the Food Chemicals Codex reveal that somewhat more than 20 moles of ethylene oxide are combined.

Topics: Chemistry, Pharmaceutical; Excipients; Hexoses; Pharmacopoeias as Topic; Polysorbates; United States