Visualization and quantification of an active ingredient in hair fibers: an example with the penetration of Coconut oil
Podium 29
Presented by: Sylvie Marull Tufeu
The hair shaft is mainly made up of three layers, the cuticle, the cortex and the medulla. Hair shaft cells have different shapes, they are densely packed, and display tight imbrication patterns. Cells are keratinized, making the hair shaft one of the most complex organic tissues to analyze. This complexity affects the preparation of the sample. As a consequence, the localization and quantification of an active ingredient may prove a difficult task.
Lipids are crucial components of hair structure, and as such appear as essential ingredients of hair care. Lipids intercalate into keratin dimers, and their removal by damage severely impairs hair integrity.
Coconut oil is commonly used in hair care products. It is composed of triglycerides made up of medium-chain fatty acids (mainly lauric acid). Such a molecular structure is believed to enhance the penetration of coconut oil into the hair, thereby making it an excellent candidate for claiming in-depth nutrition. Our goal is to implement a combination of sensitive and selective methods to identify, quantify and localize an exogenous lipid ingredient inside the hair shaft.
The quantification of coconut oil in hair may be achieved using tritium-labeling. Nonetheless, one drawback of radiolabeling techniques is that they require to be implemented in a specific and constraining environment. We have chosen to separate and quantify lipids from hair by High Performance Thin Layer Chromatography (HPTLC). First, we optimized the extraction step using a specific grinding device. Fine grinding allows a better access to the material for lipid solvents extraction. HPTLC lipid separation protocol was further optimized by choosing adequate mobile and stationary phases. Trilaurin was chosen as a reference. Semi-quantification was obtained after primulin spraying and UV detection.
The penetration of coconut oil into the hair shaft has been evidenced using equipment such as Secondary Ion Mass Spectrometry-SIMS. However, the method displays some limitations regarding the fine localization of the coconut oil. A recent study allowed to detect lipids in hair fiber with the Nile red dye combined to confocal microscopy. We optimized the test, particularly regarding sample preparation, by sectioning in a cryostat following ice embedding. We enhanced the reactivity of the dye, reduced the duration of analysis, and improved the spatial resolution. Using Nile red staining, we showed a higher signal intensity in coconut-treated samples, compared to untreated hair. The signal appears in the cell membrane complex (CMC) of the cortex, in the medulla and in the nuclear remnants. Lipids were also detected in the CMC of the cuticle and in the endocuticle area.
In this work, we have shown, by optimizing two conventional methods, both quantification and localization of coconut lipid components in the hair shaft. As to localization, the quality and resolution of the signal were good enough to distinguish the endocuticle from the exocuticle. Until now, such as resolution could only be expected using electron microscopy. This work allows us to consider the study of other active ingredients and aim at better understanding the link between the chemical function of the ingredient and the internal structure of the hair. Ultimately, this work will help predicting the effectiveness of hair care products
Lipids are crucial components of hair structure, and as such appear as essential ingredients of hair care. Lipids intercalate into keratin dimers, and their removal by damage severely impairs hair integrity.
Coconut oil is commonly used in hair care products. It is composed of triglycerides made up of medium-chain fatty acids (mainly lauric acid). Such a molecular structure is believed to enhance the penetration of coconut oil into the hair, thereby making it an excellent candidate for claiming in-depth nutrition. Our goal is to implement a combination of sensitive and selective methods to identify, quantify and localize an exogenous lipid ingredient inside the hair shaft.
The quantification of coconut oil in hair may be achieved using tritium-labeling. Nonetheless, one drawback of radiolabeling techniques is that they require to be implemented in a specific and constraining environment. We have chosen to separate and quantify lipids from hair by High Performance Thin Layer Chromatography (HPTLC). First, we optimized the extraction step using a specific grinding device. Fine grinding allows a better access to the material for lipid solvents extraction. HPTLC lipid separation protocol was further optimized by choosing adequate mobile and stationary phases. Trilaurin was chosen as a reference. Semi-quantification was obtained after primulin spraying and UV detection.
The penetration of coconut oil into the hair shaft has been evidenced using equipment such as Secondary Ion Mass Spectrometry-SIMS. However, the method displays some limitations regarding the fine localization of the coconut oil. A recent study allowed to detect lipids in hair fiber with the Nile red dye combined to confocal microscopy. We optimized the test, particularly regarding sample preparation, by sectioning in a cryostat following ice embedding. We enhanced the reactivity of the dye, reduced the duration of analysis, and improved the spatial resolution. Using Nile red staining, we showed a higher signal intensity in coconut-treated samples, compared to untreated hair. The signal appears in the cell membrane complex (CMC) of the cortex, in the medulla and in the nuclear remnants. Lipids were also detected in the CMC of the cuticle and in the endocuticle area.
In this work, we have shown, by optimizing two conventional methods, both quantification and localization of coconut lipid components in the hair shaft. As to localization, the quality and resolution of the signal were good enough to distinguish the endocuticle from the exocuticle. Until now, such as resolution could only be expected using electron microscopy. This work allows us to consider the study of other active ingredients and aim at better understanding the link between the chemical function of the ingredient and the internal structure of the hair. Ultimately, this work will help predicting the effectiveness of hair care products