Urea incorporated into ordered mesoporous silica for potential cosmetic application

Urea's thermal instability and burning on sensitive skin can cause problems for cosmetic formulations. To overcome these drawbacks, urea was incorporated into ordered mesoporous silica (SBA-15). SBA15 was synthesized using tetraethyl orthosilicate and Pluronic (R) P12(3) in an acid medium. Urea (20 wt.%) was incorporated into calcined SBA-15 by the incipient wetness impregnation method. Several techniques were used to characterize the samples. Skin hydration and transepidermal water loss were measured using Corneometer (R) CM 825 PC and Tewameter (R) 300 TM. Results showed that the structural properties of SBA-15Urea were similar to pure SBA-15, indicating that SBA-15 remained structured even after urea incorporation. Nitrogen physisorption data showed the volume and surface area of the pores in SBA-15Urea were much lower than those in SBA-15, demonstrating that urea was deposited inside the mesopores. In vivo moisturization studies revealed that SBA-15Urea was not able to reduce transepidermal water loss compared to the other products and control, while forming a non-occlusive surface film on the skin. We conclude that incorporation of urea in the pores of the inorganic SBA-15 matrix is a promising approach to enhancing its stability and providing a prolonged moisturizing effect.