Diagnosis of sunscreen residue on skin with portable Raman microscope

Abstract

It is well known that ultraviolet ray (UVR) irradiation can cause cutaneous damage, hence dermatologists encourage people to use sunscreen to absorb or reflect a number of the sun's UV radiation on the skin exposed to sunlight. In recent years, sunscreen is extensively used in our daily life to protect the damage to our skin by the sun. Among the complex components in sunblock, Titanium Dioxide (TiO2) is an important one due to its ultraviolet ray filterable ability. For the purpose of improving the performance of sun cream products, the popularity of replacing nano-sized titanium dioxide particles with normal TiO2 has increased rapidly, however, like many other technologies, nanotechnology offers both pros and potential cons, scientists have found that due to the nanoparticles’ (NPs’) enhanced physicochemical property, NPs are more active, thus they have greater opportunity to interact with cells and lead to certain cytotoxicity, may potentially damage skin and even able to diffuse into circulation system to induce skin cancer. One believed way to minimize the potential side effects is to wash TiO2 NPs away from skin at the end of the day. However, the effectiveness of this strategy hasn’t been evaluated, which might be due to the lack of a user-friendly and convenient technology for skin analysis. Here, we show for the first time that the portable Raman microscope can reveal and quantify the residue of TiO2 NPs on the skin after

cleaning. By taking porcine skin as the example, we prove that cleaning with detergent is the quickest and most efficient way to remove TiO2 NPs from the skin.