Nanostructured transparent solutions for UV-shielding: Recent developments and future challenges

Ultraviolet (UV) radiation is known to promote health concerns that can manifest over both short and long terms. Aging, sunburn, skin cancer, and other conditions are related to UV radiation. Medication can also be negatively affected by this radiation. Moreover, UV radiation modifies the taste, colour, and texture of food, and may compromise its suitability for human consumption. Therefore, the development of UV-shielding materials attracts considerable research interest for numerous applications, such as UV-light resistant packaging, sunscreens, contact lenses, coatings, and even clothes. UV-shielding materials arise from the dispersion of a UV-absorber of inorganic (such as ZnO, TiO2, CeO2) or organic (such as lignin, nanocellulose) nature into a matrix of high transparency (usually polymer or glass based). The most common types of UV-absorbers are semiconductor particles, quantum dots, or a hybrid approach combining both. However, inhomogeneous dispersion and large size distributions of the absorbing agent(s) usually compromise the transparency of the UV-shielding material. The goal of the current study is to present the newest and most innovative approaches regarding the development of nanostructured transparent solutions for UV-shielding.