ZIF-8 Templated Synthesis Of Functional Nanocapsules And Their Applications

Metal-organic frameworks?MOFs?are a class of porous polymeric materials,consisting of infinite lattices built up of the metal ions and organic linkers.As a prototypical MOF,ZIF-8 is a zeolitic imidazole-based MOF with large cavities interconnected by narrow windows.The material presents good thermodynamic and chemical stability,and easily to be synthesized.It is a simple and effective method to design and synthesize new functional materials by using MOFs as precursor or self-template,and the derivatives inherit the advantages of MOFs,such as rigid structure,high specific surface area,uniform pore size distribution,and exhibiting high catalytic,conductive and capacitive properties.In this paper,polydopamine?PDA?yolk-shell nanocapsules and hollow nanocapsules with good biocompatibility were prepared,inspired by these,the zinc ion nanocapsules with sustained-release effect were constructed,and Si-doped ZnWO₄@ZnO nanocapsules with open-shaped structures were prepared.In addition,the applications of functional nanocapsules were studied.Firstly,PDA yolk-shell nanocapsules and PDA hollow nanocapsules with an average size of?138 nm in diameter were prepared by an aqueous one-pot synthesis method utilizing ZIF-8 as a sacrificial template without any special etchant.The resulting PDA nanocapsules show negligible cytotoxicity in HeLa cells which implies their potential as candidates for practical applications in drug transport and targeting.Secondly,the zinc-releasing nanocapsules were constructed by PDA@ZIF-8.Notably,we found the self-polymerization of dopamine can form nanoshells around the ZIF-8 nanocrystals,which served as a type of functional membranes during the release of zinc.In addition,the hybrid nanocapsules expressed stronger inhibition to the cancer cell growth after encapsulating with hydrophobic antineoplastic drugs.Finally,we reported that the Si-doped ZnWO₄@ZnO nanocapsules with open-shaped structures by a facile encapsulation-calcination strategy derived from ZIF-8and polyoxometalates.A prominent degrade efficiency was obtained from Si-ZnWO₄@ZnO nanocapsules,for the Rhodamine B was degraded by 90%at 90 min.The possible photocatalytic reactions mechanisms are presented based on density functional theory?DFT?calculations.