Study on hyaluronic acid aquaphotomics-from one dimension to two dimension analysis

Hyaluronic acid (HA) is widely used in cosmetics because of its unique hygroscopic properties. However, it is difficult to characterize the interactions between HA and water molecules in the skin. In this study, we developed a fast and nondestructive method for visualizing skin water species based on aquaphotomics to elucidate the mechanism by which HA affected water species. The first HA-water system was introduced to investigate the relationship between HA and water species based on near-infrared (NIR) spectroscopy and aquaphotomics. NIR-hyperspectral imaging was then applied to characterize the distribution of different water species in the skin. The HA-water system results indicated that oligo HA had hydration behaviors opposite to those of low molecular weight HA. NIR hyperspectral imaging results showed that the intensity and spatial distribution of each water species within the skin model can be directly characterized by upgrading aquaphotomics from one-dimensional to two-dimensional. Studies showed that HA tetrasaccharides and 600-700 k Da HA could maintain the strength of skin water species. In summary, the visual representation of water species distribution enables rapid and nondestructive monitoring of macromolecule hydration with skin which could help cosmetics formulators to optimize their HA formulation to realize their best hygroscopic properties in the future.