Lecithin-based nanoemulsions

Lipid-based emulsions with particle sizes in the submicron range have been extensively investigated as vehicles for various active agents during the last decades. This review summarizes the current knowledge about nanoemulsions with a special focus on nanoemulsions comprising lecithin as the main emulsifier. A short introduction is given on the origin of lecithin-based nanoscale emulsions and the properties of these metastable systems. The differences between nanoemulsions and microemulsion phases are highlighted and recent discrepancies in terminology are discussed. Furthermore, the peculiarities of lecithin as emulsifying agent are presented. The production and optimization of nanoemulsions as well as the controversy concerning the different proposed production methods is another important aspect that is covered in detail. Moreover, general information about the stability and characterization of lecithin-based nanoemulsions is included. The last part of the review deals with current applications and research focuses with emphasis on the application of lecithin-based nanoemulsions on skin.