Targeted keratin repair: A plant-based approach to hair strength and surface restoration

Chemical and thermal stress disrupts the intramolecular and intermolecular interactions that stabilize hair keratin, leading to structural degradation and reduced mechanical strength. This study evaluates a plant-derived amino acid complex (Avena strigosa seed extract) for its ability to reinforce keratin intra-bonding and restore hair fibre integrity.

Chemically damaged human hair was treated with formulations containing A. strigosa complex. Structural and surface changes were assessed by scanning electron microscopy (SEM), inverse gas chromatography (IGC) and glossmetry. Mechanical performance was quantified via tensile testing. Molecular interaction with keratin was examined using nano-differential scanning fluorimetry (nano-DSF) and thiol-binding fluorescence assays. A split-head in vivo study (n = 20) evaluated sensory and visual attributes after a single shampoo application.

Treatment with A. strigosa complex significantly improved hair properties. SEM revealed cuticle resealing and reduced porosity; Brunauer-Emmett-Teller-specific surface area decreased by 23% compared to bleached control. Gloss increased by 105% after five wash cycles, and tensile strength improved by up to 30% in leave-on treatments (p < 0.001). Nano-DSF indicated direct interaction with keratin (thermal shift: -3.18°C), and thiol-binding assays showed a 9.2% reduction in free sulfhydryl groups, confirming protection of disulphide bonds. In vivo, hair treated with A. strigosa complex scored higher for shine and smoothness versus placebo (mean difference + 1 point; p < 0.05).

A. strigosa complex reinforces keratin intra-bonding by stabilizing hydrogen and ionic interactions and preserving disulphide integrity, resulting in measurable improvements in strength, gloss and surface quality. This targeted approach offers a validated strategy for repairing chemically damaged hair.