Gold Nanorods Identified as Potential Thermal Aging Protectors by Blocking Infrared-A

In a recent study featured in Colloids and Surfaces A: Physicochemical and Engineering Aspects, researchers from the University of Suwon and Kumoh National Institute of Technology in the Republic of Korea unveiled a groundbreaking discovery regarding the capacity of gold nanorods (GNRs) to effectively block Infrared-A (IR-A). The findings suggest a potential application of GNRs in skincare formulations to mitigate thermal aging.

Metal nanoparticles such as gold have drawn attention in nanomedicine due to their low chemical reactivity and excellent biocompatibility.

The study highlights that traditional UV filters like TiO2 and ZnO, while effective in scattering IR-A, lack the ability to absorb it. Moreover, these materials often present cytotoxicity concerns when employed for this purpose.

In contrast, metal nanoparticles, specifically gold, have emerged as promising candidates in nanomedicine due to their low chemical reactivity and exceptional biocompatibility. The authors emphasize the phenomenon of surface plasmon resonance exhibited by gold nanoparticles, particularly in the direction of IR-A wavelengths. They note that as the aspect ratio of GNRs increases, there is a corresponding red shift in the absorption wavelength.

The investigation systematically delves into the IR-A-blocking capabilities of GNRs with varying aspect ratios, augmented by scattering materials such as TiO2 or ZnO nanoplates. Comprehensive assessments, including cell viability tests on human fibroblasts and clinical trials, were conducted to validate the safety and efficacy of GNRs as effective IR-A blockers.

Despite these positive findings, the authors caution that the strong absorption characteristic of GNRs implies low reflectance at IR-A wavelengths. To address this, the study suggests combining GNRs with materials possessing high refractive indices to formulate advanced IR-A-blocking composites.