Biomimetics through bioconjugation of 16-methylheptadecanoic acid to damaged hair for hair barrier recovery

The primary component of the lipid barrier on human hair, which is essential for defense against aging and environmental stresses, is 18-methyleicosanoic acid (18-MEA), which provides hydrophobic properties and protective benefits. Since 18-MEA cannot be regenerated once damaged, developing technology that can permanently bind alternative materials to hair is critical. Once 18-MEA was removed from hair via X-ray photoelectron spectroscopy (XPS), pentaerythritol tetraisoosterate (PTIS) was hydrolyzed and observed via gas chromatography/mass spectrometry (GC/MS) to confirm that it mimicked 18-MEA, and 16-methylheptadecanoic acid (16-MHA) was obtained at pH 4 or lower. 16-MHA was bioconjugated to damaged hair from which 18-MEA was removed via a carbodiimide reaction using polycarbodiimide. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that 16-MHA remained on the surface of the bioconjugated hair even after washing. Observation of the endothermic reaction of moisture in hair via a differential scanning calorimetry (DSC) and evaluation of the moisture content confirmed that the physical properties of hair enriched with 16-MHA were similar to those of virgin hair. This biomimetic approach has been shown to restore both external structural integrity and internal moisture homeostasis.