Cosmetoceuticals in modified microemulsions

Nissim Garti*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

A novel technology to prepare modified reverse microemulsion (denoted NSSL, nanosized self-assembled liquid) vehicles loaded with cosmetoceuticals, based on permitted ingredients that can be progressively diluted with water, was developed recently in our labs. The microemulsion isotropic regions representing water-in-oil (W/O), bicontinuous mesophase, and oil-in-water (O/W) microemulsion structures are presented in a phase diagram so-called U-type. In such compositions in the isotropic regions of the phase diagram, structures can invert from L2 (reverse micelles) to an L1 (direct micelles) phase via W/O, bicontinuous, and O/W regions progressively, without phase separation. The concentrates (condensed reverse micelles) can be loaded at very high solubilization capacities of guest molecules (lycopene, phytosterols, tocopherols, CoQ10, lutein, antioxidants, aromas, fragrances) that are oil soluble or even mostly insoluble in the water or oil phase. The solubilization exceeds manyfold that of the solubility capacity of each of the phases. The microemulsion phase transformations were studied by conductivity, viscosity differential scanning calorimetry (DSC), and self-diffusion-nuclear magnetic resonance (SD-NMR) measurements, and the microstructure was determined by small-angle x-ray scattering (SAXS), cryo-transmission electron microscopy (TEM). The loci of the solubilizate at any given water content were determined by following the self-diffusion coefficients of each of the ingredients. It was concluded that the solubilizates are easily accommodated and tightly packed at the concave, hydrophobic-in-nature, water-in-oil interface and at the bicontinuous interface. Most solubilizates are more loosely packed at the oil-inwater interface and tend to be released from the interface once inversion occurs. Upon inversion to O/W microemulsion droplets, the interface becomes more hydrophilic and convexes toward the water, becoming the continuous phase. The solubilization capacity drops dramatically, and the active matter can be trigger released. The nutraceuticals are solubilized at higher solubilization capacities if interacting with the surfactant. Upon entrapping guest molecules, the transition from W/O to bicontinuous, and thereafter to an O/W microemulsion, is occurring, in some cases, at higher levels of water dilution, while in other cases, depending on the nature of the solubilizate, at lower dilutions, indicating that some of the guest compounds add some order to the internal microemulsion organization, while others are destructive to the interface and enhance phase separation or phase transitions.

Original languageEnglish
Title of host publicationSurfactants in Personal Care Products and Decorative Cosmetics, Third Edition
PublisherCRC Press
Pages211-234
Number of pages24
ISBN (Electronic)9781420016123
ISBN (Print)1574445316, 9781574445312
DOIs
StatePublished - 1 Jan 2006

Bibliographical note

Publisher Copyright:
© 2007 by Taylor & Francis Group, LLC.

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