Although summer sunny days are now only a memory, scientists continue to work on new solutions to protect the skin from harmful ultraviolet radiation. Creams with UV filter currently available on the market can be divided into two categories. Filters of organic origin (colloquially called chemical) are substances that penetrate the skin, where they absorb solar radiation and break down under its influence. Therefore, they sometimes cause irritation and are not recommended for children or people with sensitive skin. Inorganic filters - otherwise physical or mineral - will be definitely more suitable for these groups. They are based on metal oxides such as titanium dioxide and zinc oxide. Filters created in this way act like hundreds of micro-mirrors covering our skin - they reflect social rays without being degraded. They are safer in so far as they do not penetrate deep into the skin. However, it is rarely mentioned that titanium dioxide can react with other components of commercial creams under the influence of ultraviolet radiation. The reactive oxygen species (ROS) formed at that time are responsible, for example, for DNA damage and accelerate the skin aging process.
The new material created by scientists from the Faculty of Chemistry of the Jagiellonian University was created precisely with the effect of the cream on the aging of cells in mind. It is based on zinc oxide nanoparticles (Zno), which are coated with chitosan (CS) - a biocompatible polymer. Zinc oxide is a mineral commonly used in the cosmetic industry in anti-acne creams, baby powders and powders, as well as in color cosmetics and dietary supplements. It has drying properties and accelerates the regeneration of damaged tissues. It is safe for health, although it can be harmful when used in excess. Chitosan is, in turn, a biodegradable polymer obtained from the chitinous shells of marine crustaceans. It is widely used in the agricultural industry and is also used to create dressings. Its structure is similar to that of hyaluronic acid, so it has bactericidal properties and stimulates the activity of cells of the immune system. The cosmetics industry has recently appreciated its moisturizing and regenerating properties.
The zinc oxide-chitosan nanocomposite is chemically stable when exposed to ultraviolet radiation. Thus, it effectively eliminates the risk associated with the use of semiconductor minerals as active ingredients in sunscreen. At the same time, this composite perfectly absorbs UVA and UVB radiation, protecting the skin against sunburn. What really sets it apart is the fact that it is indifferent to skin cells and does not accelerate the aging process of keratocytes. At the same time, the presence of chitosan affects the high bactericidal activity - the composite is effective even against resistant strains of bacteria such as Staphylococcus aureus or Escherichia coli.
For now, scientists are still working on improving this revolutionary formula. After the research, a modern filter could be used not only in sunscreen, but also in medical devices and cosmetics for people with sensitive skin who needs additional protection. A cream created on the basis of this composite could effectively protect the skin against excess sun and drying, while helping to avoid infection. This multifunctionality is particularly important where we care about using natural cosmetics with a small number of ingredients.
Healthy, nourished and non-irritated skin is the basis of our well-being. So it's good to know that scientists are researching the effects of cosmetics on aging processes and are proposing new, safer solutions to the cosmetics industry. It is a field of science that strongly affects the comfort of our lives. The use of sunscreen cream is obviously particularly important during the holiday season, when the sun is the most. It is worth remembering, however, that also in winter on sunny days protective cosmetics should be used, especially if we spend time actively - skiing or sledding.
Author: Katarzyna Nowacka