Cellular damage mechanism induced by photo-excited titanium dioxide nanoparticles used in sunscreens.

BECERRA M. CECILIA; VAUDAGNA M.V; AIASSA VIRGINA; ARIANA ZOPPI; SILVERO C., M. JAZMIN

CÓRDOBA

Otro; V Reunión del Grupo Argentino de Fotobiología; 2020

GRAFOB

Titanium dioxide (TiO2) is widely used in sunscreens because it protects against UV radiation. Current ones are micronized or nanoparticle formulations (TiO2@NP), which blend with the skin tone and attain a better cosmetic effect. Nanosized titanium dioxide is approved by the Food and Drug Administration, but its biocompatibility is controversial. Concern about negative effects has lately been raised. In fact, cytotoxicity and oxidative stress produced by TiO2@NP when exposed to sunlight were demonstrated in some studies. The goal of this work was to propose an alternative to the cellular damage generated upon the interaction of TiO2@NP with sunlight.Antioxidant vitamins B2 (riboflavin) and vitamin C were tried as functionalization agents because their potential to bind to the nanoparticle and the capacity of neutralize the oxidative stress. Binding was achieved after a few minutes of sonication in aqueous media, followed by characterization. We used a model of prokaryotic cells (methicillin-sensitive Staphylococcus aureus biofilm) exposed to light to study the protective capacity of vitamins@TiO2NP. Viability was assessed using the XTT assay. The absorbance values are proportional to the metabolic activity of the cells and indicate cell survival. The TiO2@NP functionalized with vitamin B2 were the more stable ones, and were chosen to follow the experiments. The analysis of the supernatant by UV-Vis spectrometry showed that every gram of TiO2@NP is loaded with 0.8 grams of vitamin B2. The IR spectrum of vitaminB2@TiO2NP showed signs of binding between compounds. The OH bending peak (1634 cm-1) corresponding to bare nanoparticle disappeared and the NH2 bending band characteristic of vitamin B2 appeared (1650 cm-1). In samples treated with vitaminB2@TiO2NP irradiated for up to 6 h, the levels of reactive oxygen species (NBT assay) and protein oxidation (AOPP assay) were completely decreased. The lipid oxidation (MDA assay) was also remarkably lower when using vitaminB2@TiO2NP (64 % less). The bare oxide NPs are harmful, in part, because both anatase and rutile forms are semiconductors and produce high amounts of ROS upon sunlight. Moreover, the cell viability percent for prokaryotic cells improved when they were treated with vitaminB2@TiO2NP (153 ± 9%) compared to the ones treated with bare TiO2@NP (82 ± 3%).Functionalization with vitamin B2 proved to be a biocompatible and low-cost alternative to protect the cells from this oxidative stress. Therefore, we plan to continue this study on eukaryotic cells and in vivo, to check the penetration and biodistribution of the nanoparticles.BibliografíaAndreoli, C., Leter, G., Berardis, B.D., Degan, P., Angelis, I.D., Pacchierotti, F., Crebelli, R., Barone, F., and Zijno, A., 2018. Critical issues in genotoxicity assessment of TiO2 nanoparticles by human peripheral blood mononuclear cells. Journal of Applied Toxicology, 38 (12), 1471?1482. Haider, A.J., Jameel, Z.N., and Al-Hussaini, I.H., 2019. Review on: Titanium Dioxide Applications. Energy Procedia, 157, 17?29.