A Raman Spectroscopy Investigation of the Resilience of Hair Cuticular Scales Under Uniaxial Stress

This study investigates the mechanical response of human hair cuticles under uniaxial stress using Raman spectroscopy. A human hair was subjected to up to 32% strain, revealing a 1:1 correlation between cuticular strain and fiber elongation in the 3-26% range. Strain-induced changes in disulfide crosslinks were observed, with a gauche-to-trans conformational shift, particularly in the sulfur-rich A-layer and exocuticle. Despite a slight reduction in hydrogen-bond strength, no α-helix to β-sheet transition occurred. The cuticle's structural stability under stress is due to its high keratin-associated protein content and dense crosslinking. The study highlights the cuticular Cell Membrane Complex's role in facilitating scale gliding and maintaining structural integrity, crucial for hair's mechanical resilience.