A durable and stable hollow carrier based on metal–phenolic network composed of ZnII and proanthocyanidins/polydopamine

Metal–phenolic networks (MPNs), which are formed by phenolic molecules and metal ions via coordination bonds, are emerging as highly templated functional metal–organic materials. These networks are mostly used in the form of particles for short-term in vivo drug delivery; however, there is a lack of research on durable and stable MPN hollow particles as delivery carriers for in vitro applications. In this study, hollow and yolk-like hybrid cubic MPNs were prepared by etching zeolitic imidazolate framework-8 (ZIF-8) with proanthocyanidins (PCs). Polydopamine (PDA) resulting from the oxidative self-polymerisation of dopamine was deposited on the surface of the fabricated MPN to obtain a PDA coating, which enhanced the mechanical properties of the MPN. The prepared Zn II –PC/PDA capsules consisted of two layers: a Zn II –PC layer and a PDA–PDA layer. It showed stability at 25 ℃ for at least 280 days after freeze–drying. Moreover, when loaded with carvacrol , this MPN exhibited an enhanced antibacterial performance. Therefore, this study lays the foundation for the use of MPNs as long-lasting functional carriers.