On absorption of UV light, photo-generated titanium dioxide particles create singlet oxygen, superoxide anions (O2-) and hydroxyl radicals (OH-) that are potent free radicals (1,2). Irradiated particles of titanium dioxide can induce oxidative damage to DNA (2) which can lead to the development of mutant cells and skin cancers (3,4,5,6) and lipid peroxidation of essential functions on the cell membrane (7).
This article discusses the discovery of phosphorescent lithopone on watercolor drawings by American artist John La Farge dated between 1890 and 1905 and the history of lithopone in the pigment industry in the late 19th and early 20th centuries. Despite having many desirable qualities for use in white watercolor or oil paints, the development of lithopone as an artists’ pigment was hampered by its tendency to darken in sunlight. Its availability to, and adoption by, artists remain unclear, as colormen's trade catalogs were generally not explicit in describing white pigments as containing lithopone. Further, lithopone may be mistaken for lead white during visual examination and its short-lived phosphorescence can be easily missed by the uninformed observer. Phosphorescent lithopone has been documented on only one other work-to-date: a watercolor by Van Gogh. In addition to the history of lithopone's manufacture, the article details the mechanism for its phosphorescence and its identification aided by Raman spectroscopy and spectrofluorimetry.
After settling, the clear solution containing the titanium oxide, is run oil andfurther processed, whereby a roduct is obtained containing approximate y 35 per cent titanium oxide, 2 per cent sulphuric acid and 63 per cent of water. This product is known in the trade as titanium acid cake. It is a plastic mags having somewhat the consistency of mu 1 ljha've discovered that lithopone can be greatly improved by the suitable use of this titanium acid cake, and that the results obtained are dependent to a large extent upon the methods'by which this titanium acid cake is used,'in the production of lithopone.
Duan et al. administered 125 mg/kg BW or 250 mg/kg BW of anatase TiO2 (5 nm) intragastrically to mice continuously for 30 days. The exposed mice lost body weight, whereas the relative liver, kidney, spleen and thymus weights increased. Particles seriously affected the haemostasis of the blood and the immune system. The decrease in the immune response could be the result of damage to the spleen, which is the largest immune organ in animals and plays an important role in the immune response. Powel et al. demonstrated that TiO2 NPs may trigger immune reactions of the intestine after oral intake. They showed that TiO2 NPs conjugated with bacterial lipopolysaccharide, but not TiO2 NPs or lipopolysaccharide alone, trigger the immune response in human peripheral blood mononuclear cells and in isolated intestinal tissue. This indicates that TiO2 NPs may be important mediators in overcoming normal gut-cell hyporesponsiveness to endogenous luminal molecules, which may be particularly relevant to patients with inflammatory bowel disease, which is characterized by an abnormal intestinal permeability.
. Additionally, the current reliance on UV light to activate TIO2 necessitates the development of alternative activation methods to broaden its application in various settings.
On the other hand, the U.S. Food and Drug Administration (FDA) in their Final Administrative Order on Sunscreen Drug Products posted in September 2021 still accepts titanium dioxide up to 25% in the list of Generally Recognized As Safe and Effective (GRASE) in the main document, without further clarification on what kind or size of particles [9]. However, on page 24 (Sunscreen containing nanomaterials) FDA clearly “distinguish nanomaterials from other forms of these ingredients'' (zinc oxide and titanium dioxide) and ask for comments on “any particular nanomaterials that you believe should not be permitted for use in OTC sunscreen products”. To the best of our knowledge, this Agency did not ban the use of nanoparticulate titanium dioxide in any form, even though it is mentioned on page 34 that the anatase form is the more photoactive one, due to the lack of evidence with real sunscreens OTC (over the counter) in vivo. Moreover, other regulations in Latin America (MERCOSUR agreement, 2006) do not state clearly their position on the use of nanoparticulate TiO2NPs [10].
It’s true that titanium dioxide does not rank as high for UVA protection as zinc oxide, it ends up being a small difference (think about it like being 10 years old versus 10 years and 3 months old). This is not easily understood in terms of other factors affecting how sunscreen actives perform (such as the base formula), so many, including some dermatologists, assume that zinc oxide is superior to titanium dioxide for UVA protection. When carefully formulated, titanium dioxide provides excellent UVA protection. Its UVA protection peak is lower than that of zinc oxide, but both continue to provide protection throughout the UVA range for the same amount of time.
Titanium dioxide (TiO2) is a multifunctional semiconductor that exists in three crystalline forms: anatase, rutile, and brookite. Owing to an appropriate combination of physical and chemical properties, environmental compatibility, and low production cost, polycrystalline TiO2 has found a large variety of applications and is considered to be a promising material for future technologies. One of the most distinctive physical properties of this material is its high photocatalytic activity (Nam et al., 2019); however, more recently it has attracted growing interest because of its resistive switching abilities (Yang et al., 2008).
The efficient dispersion of TIO2 within water systems requires precise engineering to ensure maximum contact with contaminants The efficient dispersion of TIO2 within water systems requires precise engineering to ensure maximum contact with contaminants