Confocal Raman spectroscopy study of hair fiber: oil permeation

Abstract

With the various forms of hair treatments, the challenge is to find oils that can better penetrate the hair fiber. The study aims to analyze the permeation of copaiba, andiroba, and coconut oil into human hair. Methods: Five untreated hair fibers were considered as a control, and five treated fibers for each oil were tested. The treatment consisted of depositing 10 µl of the test oil on the five fibers. Raman spectra were collected before and after 30 minutes of treatment with the oils, from the surface to a depth of 40 µm. After identifying the peaks, the concentration of the permeated oil was determined. Results: The calculation of the area under the curve revealed the average permeation profiles in the hair fiber. The quantification of the concentration of permeated oil showed proximity between copaiba oil (30.14 a.u.) and coconut oil (27.85 a.u.). However, andiroba oil, despite penetrating the deeper layer, had a lower concentration compared to other oils. Conclusion: This study demonstrated the efficiency of copaiba, coconut, and andiroba oils in terms of permeation in hair fibers, providing valuable information for the development of products capable of reaching specific layers of hair fibers.