Potential of gold nanorods as IR-A blocking agents for cosmetics

Abstract

Biocompatible gold nanorods (GNRs) offer a promising solution for blocking infrared type A (IR-A) radiation owing to their strong plasmon absorption in the IR-A wavelength range of λ = 700–1400 nm. These properties make GNRs attractive candidates for the development of skincare products and protective agents against IR-A-induced thermal aging. In this study, we systematically investigated the thermal blocking performance of various creams containing GNRs under IR radiation. To enhance the IR-A blocking capabilities, we combined the GNRs with scattering materials that have high refractive indices in the IR-A region, such as TiO2 and ZnO nanoplates. We then explored the synergetic materials with the GNRs that can exhibit an optimal IR-A blocking efficiency. In addition, we evaluated the impact of the IR-A blocking agent on human fibroblasts by investigating its effects on the cell viability, matrix metalloproteinase-1 expression, and reactive oxygen species production, compared to a control group exposed to IR-A without the blocking agent. Moreover, clinical trials were conducted to validate the effectiveness of the developed IR-A blocking agent.