Protein Disulfide Isomerase-Mediated Grafting of Cysteine-Containing Peptides onto Over-Bleached Hair

The study investigated the use of Protein disulphide isomerase (PDI) to graft cysteine-containing peptides onto over-bleached hair to restore its properties. Peptides based on human keratin and lung surfactant proteins, linked to a fluorescent dye, were used to assess penetration and effectiveness. After eight bleaching treatments, hair showed 42% less mechanical resistance and decreased α-helix denaturation properties. PDI facilitated peptide attachment and penetration into the hair cortex, improving mechanical and thermal properties, including increased α-helix denaturation enthalpy, Young's modulus, and tensile strength. The peptide treatment with PDI showed promise for hair-care applications.