Polyphenols adsorption in mesoporous silica materials. Research of their application as sunscreens

Abstract

Synthesis of ordered mesoporous materials has been growing since its discovery in the 90s. Since then many techniques were developed for their synthesis and also new applications for the obtained materials. These materials have a large surface area that allows us adsorbing molecules that may act as ultraviolet filters (such as polyphenols). Ordered mesoporous silica was succesfully synthesized and characterized by SEM,TEM and BET. (+)-Catechin was adsorbed on the materials to act as sunscreen (adsorption has been characterized by TGA). Experimental design of emulsions was performed with a 23 experimental design with three central points to study the stirring rate, addition rate and disperse phase percentage (controlled variables) to see how they may affect to variables such as drop size or emulsion rheology (response variables). Different characterization techniques (rheology, microscopy and light scattering) showed that there was a relation between controlled variables and response variables. E.g. stirring rate affected directly to drop size because when we agitated faster we got smaller drops. After that we mixed the most stable emulsion with our mesoporous material containing (+)-Catechin to test if it can be used as a sunscreen ( test has been done with a radiometer under UV light). Test was also performed on commercial sunscreen to compare with synthesized material but due to a complex matrix test did not show the expected results. Test showed that mesoporous material had UV absorption but not comparable to the commercial sunscreens.