Light-scattering investigations on dilute nonionic oil-in-water microemulsions

Abstract

Dilute 3-component nonionic oil-in-water microemulsions formulated with either a polyoxyethylene surfactant (C 18:1 E 10 or C 12 E 10 ) or the alkylamine-N-oxide surfactant, DDAO (C 12 AO), and containing either a triglyceride or an ethyl ester oil have been examined using dynamic and static lightscattering techniques. Analysis of the results showed distinct differences in the tested oil's mode of incorporation into the microemulsion droplets, with both the molecular volume of the oil and the hydrophobic chain length of the surfactant being important. For example, microemulsions formulated by C 18:1 E 10 and containing one of the larger molecular volume oils (that is, either a triglyceride, Miglyol 812, or soybean oil) or the ethyl ester of fatty acid oil, ethyl oleate, exhibited first a decrease and then an increase in hydrodynamic size and surfactant aggregation number, suggesting that the asymmetric C 18:1 E 10 micelles became spherical upon the addition of a small amount of oil and grew thereafter because of further oil being incorporated into the core of the spherical microemulsion droplet. A similar conclusion of sphericity could not be drawn for microemulsions stabilized by C 18:1 E 10 and containing one of the oils smaller in molecular volume (namely tributyrin, ethyl butyrate, or ethyl caprylate) where neither the aggregation number nor the hydrodynamic radius changed much upon the addition of oil. This result suggested that these oils were preferentially located in the interfacial surfactant monolayer, behaving in much the same way as a cosurfactant. A different trend of results, however, was seen for microemulsions prepared

Formulation development and optimization using nanoemulsion technique: A technical note

“…This may be attributed to the fact that the addition of cosurfactant may lead to greater penetration of the oil phase in the hydrophobic region of the surfactant monomers, thereby further decreasing the interfacial tension, which leads to an increase in the fluidity of the interface to take up the different curvatures required to form nanoemulsions over a wide range of compositions. 2,7 The dose of ramipril varies between 2.5 mg and 20 mg; a frequently prescribed adult dose is 5 mg. Therefore, for the present study, a 5-mg dose was selected for the development of the nanoemulsion formulation.…”

Modulation of Plasma Membrane Ca2+-ATPase by Neutral Phospholipids

“…The Inhibitory Phase-It has been reported that C 12 E 10 forms spherical micelles in aqueous solutions (45). When bilayerforming long-chain lipids are mixed with these detergent molecules, the two components mix to form mixed micelles with a similar size (Fig.…”

Design, development and evaluation of novel nanoemulsion formulations for transdermal potential of celecoxib

“…It may be due to further reduction of the interfacial tension, increasing the fluidity of the interface, thereby increasing the entropy of the system. There may be greater penetration of the oil phase in the hydrophobic region of the surfactant monomers (21,22). As we further increased surfactant concentration in S mix to 2:1 (Fig.…”