Natural melanin: a multifunctional biopigment for advanced biomedical applications

Melanin, a widespread natural biopigment, has attracted growing attention owing to its multifunctional properties and potential in novel biomaterials. This review addresses the classification, biological sources, and extraction methodology of natural melanin from animals, plants, fungi, and bacteria, focusing on its physicochemical properties and bioactivities in therapeutic and diagnostic applications. Melanin's broadband ultraviolet and near-infrared absorbance, strong antioxidant and anti-inflammatory activities, and photothermal conversion efficiency allow its incorporation in photothermal therapy, radioprotection, and wound healing platforms. Moreover, melanin's antimicrobial and antiviral activities that inhibit a diverse array of pathogens indicate its usefulness in surface disinfection and infection prevention. Current advancements in melanin-containing nanoformulations, hydrogels, and microneedle patches highlight their versatility in drug delivery, molecular imaging, and tissue regeneration. Importantly, eco-friendly extraction and utilization of natural melanin advance environmentally friendly approaches in the field of biomedical technology. This review highlights natural melanin's promise as a safe, biocompatible, and multifunctional agent, supporting its use in biomedical applications that address current healthcare challenges.