Whole-process biomimetic synthesis of melanin-like amino acid surfactants by 2-iodoxybenzoic acid mediated regioselective oxidation of pterostilbene

Amino acid surfactants have garnered increasing attention as green and safe alternatives. Bioinspired by the melanogenesis pathway, this study developed a novel melanin-like amino acid surfactant with a melanin mimetic structure by conjugating glycine to o-quinone. Pterostilbene, a versatile natural monophenol, was oxidized to form o-quinone crystals by 2-iodoxybenzoic acid in a manner analogous to tyrosinase. The molecular design achieved whole-process of melanin biomimetics in four aspects: substrate, oxidant, synthetic route, and target product structure. The chemical structure was identified using Fourier-transform infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. Melanin-like amino acid surfactant exhibited ultralow critical micelle concentration of 70 nM, along with excellent performance in emulsifying, dispersing, foaming, solubilizing, and wetting. It featured exceptional multifunctionalities, including low irritation, biocompatibility, antioxidant activity, and antibacterial activity. This design enables biomimetic synthesis of multifunctional surfactants using any monophenol substrate, expanding reaction accessibility and structural diversity for amino acid surfactant.