Study of inorganic nano-sized UV filters for cosmetic applications

Abstract

The aim of the thesis is to synthesize new inorganic UV filters embedded into mesoporous silica nanoparticles (MSN), with a reduced photocatalitic activity, though keeping their screening property. This result was obtained by two strategies: 1) the growing of a non porous silica shell on the surface of MSN containing titanium dioxide as UV filter; 2) the embedding of bismuth titanate into the pores of the silica matrix. The samples were characterized by means chemical-physical techniques, including X-ray powder diffraction (XRPD), N2 adsorption/desorption, field emission - scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis - differential scanning calorimetry (TG-DSC), diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), diffusive reflectance UV-visible spectroscopy (DRUV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalitic activity of the samples, irradiated under an UV lamp, was studied. A sunscreen formulation using the best synthesized UV filter was prepared. Its rheological properties and sun protection factor (SPF) through in vitro tests were investigated.