Synthetic melanin used in less-harsh hair dye
It was just a couple of years ago that we heard about a kinder, gentler hair dye that incorporated graphene. Well, scientists have now had success utilizing another, less exotic substance – synthetic melanin.
Ordinarily, hair-coloring products include harsh ingredients such as hydrogen peroxide, ammonia and small-molecule dyes. These are used to penetrate each hair's outer cuticle, so the colorant can be deposited inside. Use of such dyes can damage the hair over time, along with causing allergic reactions in both clients and stylists.
That's where the melanin comes in.
It's a naturally-occurring pigment that gives our hair its color. As we age, it disappears from the hairs, causing them to appear gray. In the recent past, researchers have attempted to use synthetic melanin as an alternative to traditional dyes. Unfortunately, though, in order for it to color hair effectively, high concentrations of toxic heavy metals and oxidizing agents were required.
Led by postdoctoral fellow Claudia Battistella and Prof. Nathan Gianneschi, a team from Illinois' Northwestern University has now developed a method of replacing those metals and oxidants with low heat and a small amount of ammonium hydroxide. Natural-looking dark hues are produced by increasing the concentration of the latter, while reds and golds can be achieved through the addition of a bit of hydrogen peroxide.
The overall hair-coloring process is said to be "similar to or milder than" the use of conventional dyes, plus because the synthetic melanin is deposited on the outside of each hair – leaving the cuticle unpenetrated – the process should be less harmful to the hair. In lab tests on hair samples, the coloring lasted through at least 18 washes.
The research is described in a paper that was recently published in the journal ACS Central Science.
Source: American Chemical Society