The Influence of Titanium Dioxide Particle Size on the Photo-Protective Properties of Pharmaceutical Preparations and Their Effectiveness Assessment Using Hyperspectral Imaging Methods

Background: Titanium dioxide (TiO2) is widely used as a physical filter in sunscreen formulations due to its ability to reflect and scatter radiation. The effectiveness of TiO2-based preparations depends on particle size, influencing photoprotective properties across various wavelength ranges. The aim of this study was to assess the effect of TiO2 particle size on the photoprotective properties of pharmaceutical preparations using hyperspectral imaging (HIS). Methods: This study analyses directional reflectance of skin covered with preparations containing TiO2 particles < 5 µm and <100 nm across the spectral range 400–1002 nm. Results: Preparations with TiO2 < 5 µm showed higher reflectance in both the 400–633 nm and 900–1002 nm ranges, while no significant protective enhancement was observed in the 636–897 nm range. Conclusions: Larger TiO2 particles provided more significant photoprotection across a broader wavelength spectrum, highlighting the importance of particle size selection in modern sunscreen formulations. This experimental in vitro study evaluated the photoprotective properties of pharmaceutical preparations containing titanium dioxide particles of different sizes. The measurements were performed using hyperspectral imaging in the 400–1000 nm range, covering ultraviolet and visible light.