Hierarchically Structured and Highly Dispersible MOF Nanozymes Combining Self-Assembly and Biomineralization for Sensitive and Persistent Chemiluminescence Immunoassay

Metal-organic frameworks (MOF) are promising candidates for the construction of artificial nanozymes and have found applications in many fields. However, the preparation of nanosized MOF materials with high performance and good dispersibility is still a big challenge and is in great demand as signal labels for immunoassays. In this work, hierarchically structured and highly dispersible MOF nanoparticles were facilely prepared in a one-pot method. Self-assembled micelles from PEGylated hematin were used as structured templates to mediate the formation of zeolitic imidazole framework-8 (ZIF-8) nanoparticles in aqueous solution. The encapsulation of micelles in ZIF-8 frameworks produces well-dispersed nanoparticles and generates dual-confinement effects for catalytic hematin. Owing to the hierarchical structures, the formed MOF nanozymes show enhanced peroxidase-like activity and enable persistent chemiluminescence behaviors for the luminol system. Sandwich-type chemiluminescence immunoassays for carcinoembryonic antigen (CEA) were proposed using MOF nanozymes as signal labels, and good analytical performances were achieved. The combination of self-assembly and biomineralization may open new avenues for the development of MOF nanomaterials.