TiO2/(BiO)2CO3nanocomposites for ultraviolet filtration with reduced photocatalytic activity

TiO 2 nanoparticles are typically used in sunscreens; however, they have been shown to exhibit cyto- and genotoxicity, which is related to the photocatalytic activity and the subsequent formation of reactive oxygen species when exposed to ultraviolet radiation. In this study, we synthesised nanocomposite materials consisting of TiO 2 nanoparticles and homogeneously attached (BiO) 2 CO 3 clusters with a size < 10 nm onto their surfaces. The nanocomposites were prepared using a facile precipitation approach with different atomic ratios of Bi/Ti of 0.02, 0.04, and 0.08. The TiO 2 /(BiO) 2 CO 3 nanocomposites exhibit an absorbance in the ultraviolet-visible range that is similar to that of TiO 2 nanoparticles and photocatalytic activity that is reduced by up to 60% when exposed to ultraviolet and visible light. In addition, the nanocomposites show high biocompatibility in healthy HaCaT human skin cells and Madin-Darby canine kidney cells in vitro, and more importantly, they are capable of reducing the photo-generated toxicity of TiO 2 in HaCaT cells upon irradiation with simulated sunlight. Such multifunctional nanocomposites could potentially be applied as alternative ultraviolet filter components in sunscreen formulations, reducing potential adverse effects associated with TiO 2 nanoparticles.