Cryo-transfer energy dispersive X-ray spectroscopic tomography for morphological and elemental analysis of moisture-containing sunscreen creams

Electron tomography based on a tilt-series of energy dispersive X-ray spectroscopy (EDX) maps is effective for analyzing the three-dimensional elemental distribution of materials containing multiple elements. However, EDX mapping requires a high electron dose, making it challenging to apply EDX tomography to electron-beam-sensitive materials. In this study, we demonstrated cryo-transfer EDX tomography of water-containing sunscreen cream, which easily dissolves under electron beam irradiation. Under optimal experimental conditions, the three-dimensional dispersion state of titanium oxide particles, zinc oxide particles, silicone oil, and emulsified water particles in the sunscreen cream was successfully visualized. This study provides valuable insights into the dispersion state of sunscreen components, which is crucial for improving product design and performance.