Chemists have proposed a new method of colouring hair based on polymerization of dopamine in alkaline medium. This method allows you to permanently dye any hair in dark brown color without using heavy metal salts and oxidizing agents in its composition. Moreover, this does not change the hair structure and their mechanical properties. Article published in the journal ACS Central Science.
Hair consist mainly of keratin proteins form filamentous and pigment melanin isdistributed between the protein fibers. Different hair colors arise due to the concentration and distribution of two types of melanin pigments: black and brown eumelanin rare red pheomelanin responsible for red hair and pink color of lip, nipple and genital organs. The oxidation or the leaching of melanin occurs from the hair gray or white hair. Graying of hair associated with aging, although on the regulation of the concentration of melanin in hair is influenced by many factors: metabolism, the rate of change of hair distribution of melanin in the body, sex, use of drugs or genetic abnormalities. On average, half the people by age 50, half of the hair becomes gray.
In humans the biosynthesis of melanin — a heterogeneous and polydisperse polymer consisting of derivatives of catechol — begins with the enzymatic oxidation of L-tyrosine to dopamine in the cell organelles, the melanosomes, which then undergoes oxidative polymerization. The process ends with the movement of dark melanin granules in the epidermis and hair. To date, polydopamine considered to be a synthetic substitute eumelanin.