Hyaluronic Acid: Elucidating Its Penetration Into and Effect on Hair Fibers Using Confocal Raman Spectroscopy and Biometric Techniques

The study used Confocal Raman Spectroscopy to investigate the penetration and interaction of Hyaluronic Acid (HA) in hair fibers. The researchers used different shampoo formulations on UV-irradiated and non-irradiated human hair, with low-molecular weight HA, high-molecular weight HA, and a blend of both. The results showed that the HA blend penetrated the hair cortex 5.9 times more than the placebo in non-irradiated samples and 1.8 times more in irradiated samples. The HA blend also significantly decreased spontaneous frizzing by 11%, increased the hair's elastic modulus and break force, and increased the water content in the hair shafts, indicating its potential benefits for cosmetic application.