The toxicity of P25TiO₂NPs was evaluated in both prokaryotic (Fig. 3) and eukaryotic cells (Fig. 4). The XTT assay was chosen to measure the cell viability in bacterial cultures of MSSA, a normal skin microbiota microorganism. The reduction in the viability of samples with bare NPs is notorious, possibly due to the described ROS production from the interaction of P25TiO₂NPs with light [37]. This effect seems to be avoided when they are functionalized with vitamin B2. Also, the most concentrated vitaminB2@P25TiO₂NPs sample (0.2 mg/mL) shows up to 60% more absorbance after 6 h compared to the bare NPs (due to normal cell replication). This may indicate that the antioxidant effect of the vitamin B2 coating is greater than the oxidation damage produced by the NPs. This protective capacity could be attributed to the glutathione redox cycle and the conversion of reduced riboflavin to its oxidized form [38]. Values of cell viability greater than 100% are not rare and could be understood because the XTT assay actually measure metabolic activity when reducing the tetrazole to formazan. It is usually assumed that conversion is dependent on the number of viable cells, but it could also be related to an expected increased enzymatic activity when cells are exposed to small doses of some new substance. Further analysis showed that this effect was not the only one responsible for better cell viability of vitaminB@P25TiO₂NPs treated samples.

BaS+ZnSO4→ZnS·BaSO4

The Journal of the American Institute for Conservation (JAIC) is an international peer-reviewed periodical for the art conservation profession. The Journal publishes articles on treatment case studies, current issues, materials research, and technical analyses relating to the conservation and preservation of historic and cultural works. The topics encompass a broad range of specialties including architectural materials, archeological objects, books and paper, ethnographic materials, objects, paintings, photographic materials, sculpture, and wooden artifacts. Started as the Bulletin of the International Institute for Conservation-American Group (IIC-AG), in April 1961, the Journal matured into its current form in 1977. Since that time JAIC has become a repository for the core body of conservation information through its documentation of new materials, changing methods, and developing standards in the conservation profession. The four-color publication is distributed three times a year to AIC members and museum, library, and university subscribers.