Polyphenol-Metal Complex With Dopamine for Dyeing Natural White Hair

Hair becomes white due to melanin deficiency, and hair dye can be used to restore hair color. Currently, commercial hair dyes are dominated by p-phenylenediamine (PPD) hair dyes, although PPD has been suspected of being carcinogenic. Natural plant polyphenols, when complexed with metals, produce a variety of colors that can be used for hair coloration. Gallic acid and ferrous ions self-assemble to form a network structure, and the addition of dopamine results in a composite hair dye. By using ethanolamine to unfold the natural white hair scales, dye molecules can penetrate through the hair scales to the hair cortex, and the dopamine oxidative self-polymerization in the hair dye forms an adhesion film in the hair cortex layer, thereby fixing the dye molecules. A hair washability test showed that the color difference value remained unchanged after 40 washes. Scanning electron microscope (SEM) analysis of the hair after dyeing showed that the hair dye did not destroy the hair structure. Additionally, results from hair stretch tests displayed good stretch resistance to the hair. This study shows that hair dye based on a polyphenol-metal complexes containing dopamine could be used as an alternative to PPD-based hair dyes.