Hybrid organic/inorganic TiO₂ composites for enhanced UV shielding, antioxidant and quenched photocatalytic properties

Multifunctional TiO₂ composites were prepared by hybridization of inorganic TiO₂ using skin lightening materials with antioxidant properties. TiO₂ microspheres, as a supporting material in the composite were synthesized through surfactant assisted sol-gel method. Prior to the functionalization, carboxylation treatment using monochloroacetic acid was performed to introduce carboxyl chemical binders on the surface of TiO₂ substrate. Core shell structured phenylethyl resorcinol/TiO₂ and alpha-bisabolol/TiO₂ could be obtained through condensation esterification between carboxyl groups present on the TiO₂ surface and hydroxyl groups of skin lightening materials. The obtained composite demonstrated enhanced UV light absorption ability in UVA region while suppressing photocatalytic activity of TiO₂ core. This was attributed to the inhibition of photo-induced electron transfer process by deposited phenylethyl resorcinol and alpha-bisabolol layer. In order to apply in cosmetic and dermatology fields, particularly in anti-aging and hyperpigmentation treatment, the antioxidant properties of functionalized TiO₂ were accessed by scavenging activities of ABTS˙ and DPPH˙ free radicals. Both functionalized microspheres exhibited scavenging ability towards ABTS˙ and DPPH˙ radicals. Our studies revealed that the surface modification of TiO₂ with phenylethyl resorcinol and alpha-bisabolol successfully suppress the generation of reactive free radicals and reduce oxidative damage to human skin.