Marine Biomass Derived Melanin Chitosan Composites as Natural Black Hair Colorants: Charge Reversal and Electrostatic Deposition Mechanism

This study investigates the use of marine-biomass-derived melanin–chitosan composites as natural black hair colorants, focusing on charge reversal and electrostatic deposition mechanisms. By using chitosan to reverse the charge of negatively charged squid ink particles (SIPs), the composites can effectively deposit onto negatively charged hair surfaces under moderately acidic conditions (pH 4-5). The optimal SIP-to-chitosan weight ratio of 10:1 at pH 4.7 results in the darkest and most uniform coloration. This method offers a promising natural alternative to synthetic dyes, maintaining the optical properties of melanin while enhancing safety and environmental profiles. The study emphasizes the importance of pH and weight ratio in controlling the aggregation and dispersion of the composites for effective hair coloring.