Protective effect of SLNs encapsulation on the photodegradation and thermal degradation of retinyl palmitate introduced in hydroxyethylcellulose gel

Solid lipid nanoparticles (SLNs) have been introduced as a novel carrier system for drugs and cosmetics. It has also been found that SLNs show physical UV blocking action on their own. Cetyl palmitate, glyceryl behenate and palmitic acid SLNs, all loaded with retinyl (vitamin A) palmitate, were prepared and introduced in a hydroxyethylcellulose gel. SLNs in hydroxyethylcellulose gel protect retinyl palmitate from the photo- degradation induced by UVA and UVB radiation. This effect is probably due to the light-scattering properties of SLN. Nanoparticles also protect vitamin A palmitate from thermal degradation. DSC thermal analytical examination, Z potential determination and particle size measurement confirmed the solid character of the nanoparticles, their easy dispersion and their mean diameters in the nanometer range.