Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Department of Chemistry, Bar -Ilan University, Ramat-Gan 5290002, Israel.
ACS Appl Mater Interfaces. 2022 May 11;14(18):20520-20527. doi: 10.1021/acsami.1c21006. Epub 2022 Apr 22.
Melanins are natural biopolymers that have remarkable properties including UV-protection, coloration, and antioxidant activity. Their biosynthesis is regulated both spatially and temporally and involves supramolecular templating and compartmentalization of enzymes and reactants within specialized organelles called melanosomes. In contrast, the laboratory-based bulk synthesis of melanin by tyrosine or dopamine oxidation is a poorly controlled process, resulting in materials with undefined properties. Inspired by the pigment's biosynthesis, we developed a methodology to spatiotemporally regulate melanin formation in liquid droplets. The spatial control is achieved by sequestration of the reaction in dextran-rich droplets of a polyethylene glycol/dextran aqueous two-phase system, where the use of a photocleavable protected tyrosine provides a temporal control over its enzymatic oxidation-polymerization. We show that the liquid droplets allow for confined local reactivity as they serve as reaction centers for melanin synthesis and compartmentalize the melanin product. This methodology opens tremendous opportunities for applications in skincare and biomedicine.
黑色素是天然的生物聚合物，具有显著的特性，包括紫外线保护、着色和抗氧化活性。它们的生物合成受到时空调节，涉及超分子模板和将酶和反应物分隔在称为黑素体的专门细胞器内。相比之下，通过酪氨酸或多巴胺氧化在实验室中进行的黑色素批量合成是一个控制不佳的过程，导致材料具有不确定的性质。受色素生物合成的启发，我们开发了一种时空调节液滴中黑色素形成的方法。通过将反应隔离在聚乙二醇/葡聚糖水相两亲系统中富含葡聚糖的液滴中来实现空间控制，其中使用光可裂解保护的酪氨酸提供了对其酶促氧化聚合的时间控制。我们表明，液滴允许受限的局部反应性，因为它们充当黑色素合成的反应中心，并将黑色素产物分隔开。这种方法为在皮肤护理和生物医学中的应用开辟了巨大的机会。
