Contribution of encapsulation on the biodisponibility of retinol.

To show the benefits of retinol encapsulation in cosmetic industry, we compared the diffusion of two different retinol preparations through skin:oil-in-water (o/w) emulsions of retinol, also called 'free retinol', and suspension of Cylasphere including retinol, also called 'encapsulated retinol'. Two methods were used: Franz cell elucidated retinol release and storage in a hairless mouse skin according to time for the two types of preparations. The dosage of retinol by high performance liquid chromatography (HPLC) showed that encapsulated retinol was maintained into the skin for a longer time than free retinol. Raman microspectrometry measurements established a spectral image of the skin and determined the localization of retinol. Maps were collected according to time. They detailed the shifts of free and encapsulated retinol in the epidermis of a human biopsy. Spheres were smaller than droplets and they moved two times faster at this level of the skin.