Solid Lipid Nanoparticles and Nanostructured Lipid Carriers in moisturizing cosmetics
In the last years, lipid nanoparticles have received a great attention, namely in the field of the cosmetic research. Hydration is an essential step to maintain the skin healthy. Many cosmetic active ingredients have been successful encapsulated into lipid nanoparticles. Nanoparticles proved to be very advantageous for skin application, since, when applied on the skin they form a transparent film that reduces the transepidermal water loss and increases hydration. Although SLN revels better occlusion properties, NLC were the first lipid nanoparticles appearing on the market in cosmetics products.
Currently a great interest in lipid nanoparticles exists, since these carriers have been studied in the last decade with particular attention given to cutaneous application (1).
Solid lipid nanoparticles (SLN) were developed in the early 90’s as an alternative to emulsions, liposomes and polymeric nanoparticles. Additionally, a new generation of lipid nanoparticles was developed using mixtures of solid lipids with liquid lipids (oils), which remain solid at body temperature. These systems are called nanostructured lipid carriers (NLC) and overcome the limitations of SLN, like drug expulsion during storage (2).
Both NLC and SLN have advantageous characteristics for cutaneous application, as good tolerability and close contact with the stratum corneum which allows an increase of skin hydration. In addition, also permit an increase of the chemical stability of some compounds against oxidation or hydrolysis (1).
The nanoparticle dispersions are promising systems for skin application. However, these dispersions need to be incorporated in an appropriate system for skin application, like semisolid formulations (3).