Scientists at the Faculty of Chemistry of Tomsk State University developed a cerium dioxide sol – a component that can increase the sunscreen and antioxidant activity of cosmetics. Unlike titanium and zinc oxides, which are traditionally used in creams, the new development not only protects the skin fr om ultraviolet radiation, but also slows down aging by neutralizing free radicals.
The project is being implemented with the support of the Development Program of Tomsk State University (Priority 2030) under the leadership of Lyudmila Borilo, Head of the Department of Inorganic Chemistry, TSU Faculty of Chemistry. The working group includes Svetlana Kuznetsova, professor of the Department of Inorganic Chemistry and Alexander Gordeev, graduate student of TSU Faculty of Chemistry.
— Antioxidant UV filter is used as the basis for sunscreen, which not only blocks ultraviolet light, but also neutralizes free radicals, preventing photoaging, – said Svetlana Kuznetsova. – Ceria has unique properties: due to antioxidant activity and photoprotective properties, it prevents sunburn, skin neoplasms, bacterial reproduction and slows down the aging process by recombining oxygen radicals on the surface of ceria particles.
According to Svetlana Kuznetsova, sunscreens use both organic and inorganic UV filters. Organic UV filters contain benzene rings with amino or methoxy groups, as well as carboxyl groups that absorb UV radiation in the 250-340 nm range. Such substances are quite stable, but they can penetrate deep into the skin, thus forming by-products and causing allergic reactions.
— Inorganic UV filters, such as zinc oxide and titanium dioxide nanoparticles, reflect sunlight to protect the epidermis. They do not cause irritation or allergies, making them suitable even for sensitive children’s skin. However, they also have disadvantages: photocatalytic activity and a white coating on the skin, which looks unattractive. The cerium dioxide UV filter we have developed has a light yellow color, has no photocatalytic activity, and exhibits sunscreen properties no worse than UV filters based on titanium dioxide and zinc oxide. The content of cerium dioxide is an order of magnitude lower than the content of titanium dioxide and zinc oxide in the sol. This is important for the environmental burden on water bodies. Sunscreens are actively used when tanning on the beach, creams are easily washed off the skin into natural waters (lakes, seas, rivers) when swimming. There are studies wh ere researchers find particles of titanium and zinc oxides inside fish, – explained Svetlana Kuznetsova.
The UV filter developed by TSU scientists exhibits antioxidant activity that is much higher compared to that of vitamin C. Besides, it prevents the reproduction of bacteria, including Staphylococcus aureus and E. coli, which avoids the risk of purulent inflammation on the skin.
— Currently, we continue to study the properties of this filter and improve the composition by introducing additives of other rare earth elements (REE). Depending on the REE nature in the structure of cerium dioxide, they replace either three-charge or four-charge cerium ions. The oxygen non-stoichiometry of the obtained solid solutions depends on this and, therefore, their antioxidant activity, bactericidal resistance while maintaining sunscreen properties, – added Svetlana Kuznetsova.
The sol manufacturing technology received a patent (No. 2834331) and technological regulations. According to researchers, the resulting sol can be used not only in cosmetics, but can also be added to varnish and paint, which will preserve the color and protect them from destruction when exposed to light. Now researchers want to scale up the technology and test the product with industrial partners.