Construction of hollow proanthocyanidin cages as a novel delivery system using zeolitic imidazolate framework-8 sacrificial templates

Proanthocyanidin has attracted increasing attention in recent years due to its antibacterial and antifungal properties and other health benefits. In this study, we successfully generated a novel delivery system, hollow proanthocyanidin cube cages, for cargo molecule encapsulation. First, ZIF-8 particles were prepared and etched with proanthocyanidins. Second, by accurately adjusting the ZIF-8 particle size and etching time, yolk shell metal polyphenol frameworks and hollow proanthocyanidin cube cages with various sizes were obtained. The structural and thermal properties of these yolk shell structures and hydrophilic hollow cages were analyzed. To test their potential application as functional component carriers, we loaded cypress essential oil in the hollow proanthocyanidin cube cages. These cages showed good loading capacity (26 wt%) and antimicrobial activity, especially for Aspergillus niger. In conclusion, hollow proanthocyanidin cube cages with a definite spatial structure are promising alternative carriers with potential applications in food, cosmetic, and medical fields.