Melanin-Driven Green Synthesis and Surface Modification of Metal and Metal-Oxide Nanoparticles for Biomedical Applications

Abstract

Tremendous research efforts have recently been devoted to designing and developing melanin-engineered metal and metal-oxide nanoparticles with unconventional configurations for groundbreaking applications in biomedical settings. These surface-engineered nanoparticles occupy a unique niche among nanomaterials due to the distinctive merits of melanin, such as exceptional biocompatibility, photophysical adaptability, and robust metal-binding capabilities. This review provides a comprehensive and heuristic overview of sustainable synthesis strategies of structurally tunable metal nanoparticles that can facilitate the controlled customization of melanin. Recent research is highlighted that harnesses the unique physical properties of melanin to explore how controlling its geometrical features can increase catalytic activity, which is essential for improving imaging resolution and therapeutic efficacy. Furthermore, the complex dynamics of oxidative polymerization and detailed investigation of how melanin's interface can be conjugated with metal components in hybrid nanostructures are critically analyzed. The key remaining challenges are summarized and an outlook on the future perspectives of melanin-engineered nanoparticles is offered. This review can act as a roadmap to guide both newcomers and experts who are interested in learning about the immense potential of melanin nanoparticles as versatile, high-performance platforms for future nanotechnology-driven innovations in theranostic nanomedicine.