Mapping Penetration of Cosmetic Compounds into Hair Fibers Using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

In the study titled "Mapping penetration of cosmetic compounds into hair fibers using time-of-flight secondary ion mass spectrometry (TOF-SIMS)," researchers investigated the penetration of vegetable oils into hair fibers using the TOF-SIMS method. They extended previous work that had found the method suitable for studying the penetration of coconut and mineral oils into human hair. The study revealed that oils with different molecular structures penetrated hair fibers to varying degrees. Polyunsaturated oils were found to either not penetrate or only sparingly penetrate into the hair structure, mostly remaining in the cuticular region. It was suggested that these molecules might not fit into the fiber's cell membrane complexes, which are the diffusion pathways in the keratin fiber. In contrast, monounsaturated oils, such as olive oil, with a more compact molecular structure, were observed to penetrate readily into the hair fiber. The study concluded that the molecular structure of oils influences their ability to penetrate hair fibers, with monounsaturated oils being more effective at penetration than polyunsaturated oils.