We tried to dye hair with standard and synthesized pigments and found success in all standard pigments, as well as synthesized melanin and indoline-betacyanin. Notably, the results of synthesized indoline-betacyanin was better than that of standard betacyanins.
Standard pigments (precursors)
We first tried to dye hair using standard pigments. For dopamine, 10 mM CuSO4, a certain amount of H2O2, and ddH2O were mixed. 5 mg/mL standard dopamine hydrochloride was added. We incubated the mixture at 37℃ for 2 h. For melanin and indigo, we first incubated the hair in pH=9 Ca(OH)2 at 50℃ for 40 min. Next, we added 5 or 10 mg/mL pigment and let stand at 50℃ for another 40 min. For betacyanins, Ca(OH)2 was replaced by pH=5 sodium acetate (CH3COONa) buffer since the pigment shows color in acid solution (Reshmi, Aravindhan & Devi, 2012).
Figure 1. Hair dye results with standard pigments. (A) Hair dye results with standard indigo and melanin. (B) Hair dye results with standard betacyanins. (C) Hair dye results with hydrochloride dopamine combined with hydrogen peroxide.
Next, after we successfully produced the pigments, we attempted dyeing hair with our synthesized pigments using the same protocol. Since dopamine seemed to have been oxidized, we tried dyeing hair with polydopamine using the same method as the other pigments. The hair with synthesized melanin and indoline-betacyanin were dyed successfully, and the hair with indigo was partly dyed. Notably, the hair color dyed with synthesized indoline-betacyanin was darker than that dyed with standard betacyanins. It is hypothesized that indigo failed because the concentration was too low, dopaxanthin failed because the color of the bleached hair was too similar to dopaxanthin, and polydopamine failed because the particles are too large to get into the hair.
Figure 2. Hair dye results with synthesized pigments, with positive and blank controls.
1.Reshmi, S. K., Aravindhan, K. M., & Devi, P. S. (2012). The effect of light, temperature, pH on stability of betacyanin pigments in Basella alba fruit. Asian Journal of Pharmaceutical and Clinical Research, 5(4), 107-110.