Testing samples were made mixing 100 uL of TiO₂NPs suspensions (0.2 mg/mL and 0.02 mg/mL) and vitamins@P25TiO₂NPs (0.2 mg/mL and 0.02 mg/mL) with 100 μL ATCC 29,213 methicillin-sensitive Staphylococcus aureus (MSSA) (10⁷ in PBS, pH 7). Controls were made replacing nanoparticles with the same volume of PBS. The concentrations of nanoparticle suspensions were chosen based on the FDA approved maximal and the minimal amount usually found in sunscreens, which are 20% and 2% (this is equivalent to 0.2 mg/mL and 0.02 mg/mL for nanoparticles suspensions). The cream concentration, on the other hand, was an intermediate value of 10%.

Titanium dioxide is an inert earth mineral used as a thickening, opacifying, and sunscreen ingredient in cosmetics. It protects skin from UVA and UVB radiation and is considered non-risky in terms of of skin sensitivity. Because it is gentle, titanium dioxide is a great sunscreen active for sensitive, redness-prone skin. It’s great for use around the eyes, as it is highly unlikely to cause stinging.

Lithopone