Study On The Preparation Procedure And Release Performance Of Hollow Microcapsules Composed Of Metal-phenolic Networks

Metal-phenolic networks（MPNs）are used as a modification strategy to form capsules by changing their composite materials and assembly methods to obtain functional MPN composite coatings.MPN coating has become an important method for constructing interface composites on nanomaterials.In addition,MPN coatings with different physical/chemical properties and unique stimulus responses can be manufactured using different synthetic routes or templated assembly methods.Because MPN has controllable thickness,controllable porosity,controllable mechanical strength,stimulus response and selective permeability during assembly,it can be used as a secondary modification or composite platform to process interface characteristics and give new functions to objects.Metal–phenolic networks,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 280days after freeze–drying.Moreover,when loaded with carvacrol,this MPN exhibited an enhanced antibacterial performance.It also has the effect of delaying the release of core material and has an acid-sensitive p H response.Experimental research on fruit preservation found that it can effectively delay fruit spoilage time and maintain fruit quality.Therefore,this study lays the foundation for the use of MPNs as long-lasting functional carriers.