Bioinspired Functionalized Melanin Nanovariants with a Range of Properties Provide Effective Color Matched Photoprotection in Skin.

Melanin and related polydopamine hold great promise; however, restricted fine-tunabilility limits their usefulness in biocompatible applications. In the present study, by taking a biomimetic approach, we synthesize peptide-derived melanin with a range of physicochemical properties. Characterization of these melanin polymers indicates that they exist as nanorange materials with distinct size distribution, shapes, and surface charges. These variants demonstrate similar absorption spectra but have different optical properties that correlate with particle size. Our approach enables incorporation of chemical groups to create functionalized polyvalent organic nanomaterials and enables customization of melanin. Further, we establish that these synthetic variants are efficiently taken up by the skin keratinocytes, display appreciable photoprotection with minimal cytotoxicity, and thereby function as effective color matched photoprotective agents. In effect we demonstrate that an array of functionalized melanins with distinct properties could be synthesized using bioinspired green chemistry, and these are of immense utility in generating customized melanin/polydopamine like materials.