Studies have been carried out with both emulsion paints and powder paints, both with clear results on how the use of lithopone supplier 30% reduces the appearance of algae in the paint once it has been applied (see photos).
The vitaminC@P25TiO2NPs, on the other side, did not have any effect on cell protection against ROS. This might be due to the fact that vitamin C, a well-known scavenger of ROS, could behave as prooxidant and even promote ROS and lipid peroxidation [39]. It was recently described that at small concentrations of vitamin C, the prooxidant effects dominate; while in large concentrations the antioxidant ones predominate [40]. The effect also depends on the cell state and the interaction of vitamin C with light. In this case, ascorbic acid may act as an antenna to harvest visible light when conjugated to P25TiO2NPs. Indeed, it was previously found that this combination (in some ratios) could have an improved photocatalytic activity, possibly due to a red shift in its light absorbance [41]. Further studies on vitaminC@P25TiO2NPs were not conducted, because of the poor antioxidant capacity [42].
In 2017, the Scientific Committee on Consumer Safety (SCCS) warned that they should revise their recommendations if any new evidence emerges in the future related to the potentially harmful effects of TiO2NPs used in a sunscreen formulation or if they can penetrate the skin. In fact, our work could contribute to this matter because it evaluated the skin penetration of a particular kind of TiO2NPs. [8]