Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
Department of Chemical and Biomolecular Engineering, Colburn Laboratory, University of Delaware, Newark, Delaware 19716, United States.
J Am Chem Soc. 2021 Feb 24;143(7):2622-2637. doi: 10.1021/jacs.0c12322. Epub 2021 Feb 9.
Melanin is ubiquitous in living organisms across different biological kingdoms of life, making it an important, natural biomaterial. Its presence in nature from microorganisms to higher animals and plants is attributed to the many functions of melanin, including pigmentation, radical scavenging, radiation protection, and thermal regulation. Generally, melanin is classified into five types-eumelanin, pheomelanin, neuromelanin, allomelanin, and pyomelanin-based on the various chemical precursors used in their biosynthesis. Despite its long history of study, the exact chemical makeup of melanin remains unclear, and it moreover has an inherent diversity and complexity of chemical structure, likely including many functions and properties that remain to be identified. Synthetic mimics have begun to play a broader role in unraveling structure and function relationships of natural melanins. In the past decade, polydopamine, which has served as the conventional form of synthetic eumelanin, has dominated the literature on melanin-based materials, while the synthetic analogues of other melanins have received far less attention. In this perspective, we will discuss the synthesis of melanin materials with a special focus beyond polydopamine. We will emphasize efforts to elucidate biosynthetic pathways and structural characterization approaches that can be harnessed to interrogate specific structure-function relationships, including electron paramagnetic resonance (EPR) and solid-state nuclear magnetic resonance (ssNMR) spectroscopy. We believe that this timely Perspective will introduce this class of biopolymer to the broader chemistry community, where we hope to stimulate new opportunities in novel, melanin-based poly-functional synthetic materials.
黑色素在不同生物界的生物中无处不在，是一种重要的天然生物材料。其在从微生物到高等动物和植物的自然界中的存在归因于黑色素的许多功能，包括色素沉着、自由基清除、辐射防护和热调节。一般来说，黑色素可根据其生物合成中使用的各种化学前体分为五类——真黑色素、褐黑色素、神经黑色素、异黑色素和焦黑色素。尽管对黑色素的研究已有很长的历史，但它的确切化学成分仍不清楚，而且其化学结构具有固有的多样性和复杂性，可能包括许多有待确定的功能和特性。合成模拟物已开始在揭示天然黑色素的结构和功能关系方面发挥更广泛的作用。在过去的十年中，作为常规形式的合成真黑色素的聚多巴胺已主导了基于黑色素材料的文献，而其他黑色素的合成类似物则受到的关注要少得多。在这篇观点文章中，我们将讨论黑色素材料的合成，特别关注聚多巴胺之外的合成。我们将强调阐明生物合成途径和结构表征方法的努力，这些方法可以用于研究特定的结构-功能关系，包括电子顺磁共振（EPR）和固态核磁共振（ssNMR）光谱。我们相信，这一时事相关的观点将把这种生物聚合物介绍给更广泛的化学界，我们希望在新型、基于黑色素的多功能合成材料方面激发新的机遇。
