Supramolecular Engineering of Melamine–Barbiturate Assemblies for Polyphenol Encapsulation and Antioxidant Delivery

Supramolecular assemblies of melamine–barbituric acid (Mel-BA) were engineered for the controlled encapsulation of polyphenols, as exemplified by epicatechin (EC). Quantum chemical (DFT) calculations verified the thermodynamic viability of incorporation, although steric and geometric constraints introduced structural defects. EC displayed a binding affinity for Mel-BA higher than that of gallic acid, facilitated by its additional aromatic rings. Encapsulation modulated particle morphology, yielding spherical Mel-BA-GT particles (∼10 μm) and larger, nonspherical Mel-BA-EC assemblies (∼15 μm). The hybrids demonstrated potent antioxidant activity (∼60% over 5 min) with sustained release profiles at pH 8.0, underscoring their delivery potential. The emergence of RHOD-channel fluorescence in the hybrids indicated lattice defect formation upon polyphenol inclusion. Remarkably, electron paramagnetic resonance revealed that carbon-centered radicals within Mel-BA-GT remained stable, implying spatial segregation between matrix-encapsulated polyphenols and surface-localized radicals. This work advances the design of multifunctional supramolecular platforms for targeted delivery and catalysis.本研究构建了用于多酚可控包埋的三聚氰胺-巴比妥酸（melamine–barbituric acid, Mel-BA）超分子组装体，并以表儿茶素（epicatechin, EC）为例开展了相关验证。量子化学（密度泛函理论, DFT）计算证实了该包埋过程的热力学可行性，但空间位阻与几何约束会导致结构缺陷的产生。相较于没食子酸，表儿茶素对Mel-BA具有更高的结合亲和力，这得益于其额外的芳香环结构。包埋作用可调控颗粒形貌：所得Mel-BA-GT颗粒呈球形（粒径约10 μm），而Mel-BA-EC组装体则为更大尺寸的非球形结构（粒径约15 μm）。该杂化材料展现出强效抗氧化活性（5分钟内抗氧化率约60%），且在pH 8.0环境下呈现缓释特性，凸显了其作为递送载体的应用潜力。杂化材料中出现的RHOD通道荧光信号表明，多酚包埋后组装体晶格产生了缺陷。值得注意的是，电子顺磁共振检测发现，Mel-BA-GT基质内的碳中心自由基可保持稳定，这意味着基质包埋的多酚与表面定位的自由基之间存在空间隔离。本研究推动了面向靶向递送与催化的多功能超分子平台的设计开发。