The morphology of vitaminB2@P25TiO₂NPs is coherent with the description of Degussa P25 typical population. Size distribution histograms were made from manual measures of the nanoparticles observed in SEM micrographs using ImageJ®. This data showed that more than 70% is anatase (between 20 and 60 nm) with a minor amount of rutile characteristic bars (between 80 and 100 nm) and a small amount of amorphous phase (<40 nm) [36]. Further analysis of the same sample areas with an EDS probe demonstrated the presence of organic material composed of C and O (Fig. 2). This material was found homogeneously distributed on the surface of the different shapes of P25TiO₂NP, not in the background, indicating a specific interaction that could be attributed to the functionalization of the P25TiO₂NPs with vitamin B2.

The production of ROS was studied on white blood cells as a model to screen the effect on eukaryotic cells after being exposed to samples and solar simulated irradiation (according to the level of penetration under the skin). For that purpose, the leukocytes were separated from anticoagulated fresh blood using the Ficoll-Hypaque reactive in a well-known technique [33]. Then, 50 μL of suspensions of P25TiO₂NPs (0.2 mg/mL and 0.02 mg/mL), vitaminB2@P25TiO₂NPs (0.2 mg/mL and 0.02 mg/mL) and vitamin B2 (0.2 mg/mL and 0.02 mg/mL) were prepared and mixed with 50 μL of white blood cells suspension. A solution of 3% H₂O₂ was used as positive control and PBS as negative control. Then, the samples were irradiated using the LED panel for 3 and 6 h to simulate the light penetration into the skin. Also, a set of samples was kept in the dark as control. Finally, the ROS were detected through the colorimetric assay employing the nitroblue tetrazolium salt (NBT salt) and the absorbance at 650 nm was measured. The experiment was reproduced twice; the standard deviation was calculated and p-value < 0.05 were considered significant.

The photocatalytic activity of titanium dioxide results in thin coatings exhibiting self-cleaning and disinfecting properties under exposure to ultraviolet radiation. Alloys are characterized by being lightweight and having very high tensile strength (even at high temperatures), high corrosion resistance, and an ability to withstand extreme temperatures and thus are used principally in aircraft, pipes for power plants, armour plating, naval ships, spacecraft, and missiles.

However, some experts and food regulators in other countries disagree – pointing to potential, serious health consequences and rising concerns about the additive. Starting August 7, for example, the use of titanium dioxide in food will be banned in the European Union.

This work was supported by SECyT-UNC Consolidar tipo I [2018-2021] and FONCyT, Argentina [grant number 0821-2014]. MVV holded a EVC-CIN scholarship from SECyT UNC. AM, MFPP AND MFC hold CONICET, FONCyT and SECyT scholarships respectively, and MJS, AZ, VA, MFP and MCB are career members of CONICET.