A Safer Shade Of Black

Polydopamine, a black substance structurally similar to melanin, could be a safer alternative to conventional chemical hair dyes.

AsianScientist (Mar. 14, 2017) – Researchers from Gyeongsang National University have mimicked melanin to produce a dye that is less allergenic than the existing chemical used to dye hair black. Their report appears in the journal ACS Biomaterials Science & Engineering.

Coloring hair has become a common practice, particularly for people who want to hide their graying locks. But an ingredient in many of today’s commercial hair dyes has been linked to allergic reactions and skin irritation. Now scientists have developed a potentially safer alternative by mimicking the hair’s natural color molecule: melanin.

The permanent hair dye ingredient p-phenylenediamine (PPD) has been associated, although rarely, with allergic reactions including facial swelling and rashes. Coloring hair with natural melanin would be an intuitive alternative to PPD.

However, previous research has found that the pigment molecules clump together, forming rods and spheres too large to penetrate into the hair shaft to create lasting color. Jong-Rok Jeon and colleagues wanted to build on the idea of using melanin but with a molecule that mimics the real thing.

The researchers turned to polydopamine, a black substance that is structurally similar to melanin and has been explored for use in a variety of biomedical applications. Polydopamine with iron ions transformed gray hairs into black and lasted through three wash cycles. Lighter shades could also be achieved with polydopamine by pairing it with copper and aluminum ions.

Toxicity tests showed that mice treated with the colorant didn’t have noticeable side effects, while those that received a PPD-based dye developed bald spots.


The article can be found at: Im et al. (2017) Metal-Chelation-Assisted Deposition of Polydopamine on Human Hair: A Ready-to-Use Eumelanin-Based Hair Dyeing Methodology.

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Source: American Chemical Society; Photo: Pixabay.
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