Melaninlike

Melaninlike refers to pigments or polymers that resemble the natural pigment melanin in color, chemical hints, or biological function. In science, melaninlike materials are typically heterogeneous polymers derived from catechol or indolic precursors that, upon oxidation and coupling, yield dark, broadband-absorbing substances. The term emphasizes similarity to melanin rather than identity; true melanin is a specific class of biopolymers formed in animals and some microbes.

Natural and synthetic sources: In nature, melaninlike pigments occur in fungi, bacteria, and plants as protective pigments. In the laboratory, researchers make melanin-like polymers by polymerizing catecholamines such as dopamine or L-DOPA, or by oxidative coupling of tyrosine derivatives, often under alkaline conditions or enzymatic catalysis. These processes produce insoluble, amorphous solids with irregular structures.

Properties: Melaninlike materials typically exhibit broad UV–visible absorption, broadband light attenuation, radical scavenging activity, and redox capabilities. Many are chemically versatile, allowing surface functionalization, and some exhibit electronic conductivity and photothermal properties. Stability and hydrophobicity vary with composition.

Applications: They are used as bioinspired coatings, antioxidants, and photoprotectants; in bioelectronics and sensors; for drug delivery and imaging; and as components in batteries or supercapacitors.

See also: melanin, eumelanin, pheomelanin, polydopamine, bioinspired materials.