Bioinspired Melanoidin-Polyphenol nanocomplex for hair protection and mechanical reinforcement with antioxidant...

Ultraviolet (UV) radiation is one of the most pervasive environmental threats to biological interfaces, driving protein denaturation, structural weakening, and oxidative stress that collectively deteriorate the quality of skin and hair. Despite their widespread use, conventional UV filters are hindered by poor coatability, photoinstability, and safety concerns, underscoring the need for fundamentally new protection strategies. Herein, we report a bioderived melanoidin/tannic acid (MD/TA) nanocomplex that self-assembles into a robust photoprotective coating through synergistic interactions with polyphenols. By leveraging the intrinsic UVA absorption of melanoidin, the broad-spectrum UV shielding of tannic acid, radical-scavenging activity, and interfacial binding, the MD/TA complex forms uniform, durable, and antioxidant-active layers on hair fibers. Beyond surface protection, the coating reprograms oxidative stress responses by suppressing ROS accumulation, thereby restoring cuticle integrity and enhancing tensile resilience. At the molecular level, it activates endogenous antioxidant pathways (SOD2, CAT) while attenuating apoptosis and inflammatory cascades (TNF-α, IL-1β) in the presence of UV irradiation. This work establishes a biocompatible, multifunctional photoprotective platform that transcends the limitations of conventional filters by combining durable adhesion with molecular-level antioxidant reprogramming. Thus, the MD/TA nanocomplex exemplifies a synergistic, bio-inspired strategy for long-lasting hair protection against UV-induced oxidative damage.