Homogeneous distribution of fatty ester-based active cosmetic ingredients in hydrophilic thin films by means of nanodispersion.

Objective: Cosmetic films and patches are interesting forms to promote skin penetration of active ingredients as they ensure their long stay on the treated zone of the skin. Nevertheless, currently developed films and patches are most of all hydrophilic and are not adapted to the hydrophobic molecules. The aim of this study was to establish whether nanodispersion of fatty acid-based active cosmetic ingredients (ACI) could be a manner to introduce high concentrations of those ACI in hydrophilic films.

Methods: Punica granatum seed oil hydroxyphenethyl esters (PHE) constitute a commercialized lipolytic cosmetic ingredient obtained by enzymatic conjugation of tyrosol to long-chain fatty acids and to enhance its skin diffusion. Nanodispersions of PHE were prepared by a green emulsion-solvent evaporation process and dispersed in polyvinyl alcohol films. Raman imaging coupled to multivariate analysis was used to study the distribution of PHE in the films.

Results: Nanodispersions of PHE combined with antioxidant vitamin E and stabilized by Pluronic® F127 were successfully prepared. The nanodispersions show a spherical shape and a hydrodynamic diameter close to 100 nm. Raman images analysis with multivariate approaches showed a very homogeneous distribution of PHE nanodispersions in the films compared to free PHE introduced as an ethanol solution.

Conclusion: Nanodispersions of hydrophobic fatty acid-based ingredients seem to be relevant method to introduce this type of ingredient in hydrophilic film matrix. The co-suspension with vitamin E limits their degradation in time.