Penetration study of oils and its formulations into the human hair using confocal microscopy

Summary Background Laser scanning confocal microscopy (LSCM) is a nondestructive method for observing the samples in three dimensions as well in their natural environment. Therefore, it is well suited for studying human hair. This investigation is focused on evaluating the comparative penetration ability of vegetable vs mineral oils and their formulations with excipient, in human hair. Aims Laser scanning confocal microscopy was employed to assess thin cross sections of human hair, treated with oils and their formulations, to comprehend their penetration capability and pattern. Methods Hair incubated with individual oils or their formulations were labeled with the fluorescent dye was cross‐sectioned into thin fragments and visualized under the LSCM. Results The mineral oil demonstrated better penetration through the hair than the vegetable oils. Combination of these oils with excipient, in an appropriate ratio, had a substantial influence on oil penetration in terms of the depth of penetration. Conclusions Our investigation proved the suitability of fluorescent‐based imaging for studying the penetration of oils across human hair. This method can be employed as a potential analytical tool to study the penetration of various hair‐care formulations and/or their additives, to estimate their effects on human hair.