Effects of Exposure\nto Different Types of Metal–Organic\nFramework Nanoparticles on the Gut Microbiota and Liver Metabolism\nof Adult Zebrafish

Metal–organic framework nanoparticles\n(MOF NPs)\nhave received\nmuch attention for their potential use in nanopesticides. However,\nlittle is known about the potential health and environmental risks\nassociated with these materials. In this study, the toxicological\nresponses of zebrafish exposed to five MOF NPs for short and long\nperiods of time were evaluated. The acute toxicity results showed\nthat the toxicity of the five MOF NPs to zebrafish embryos and adult\nzebrafish was in the order of Cu-MOF > ZIF-90 > ZIF-8 > Fe-MOF\n> Zr-MOF.\nHistopathological analysis revealed that ZIF-8, ZIF-90, and Cu-MOF\nNPs caused liver swelling and vacuolization in zebrafish. The cellular\nultrastructure showed that ZIF-8, ZIF-90, and Cu-MOF NPs severely\ndamaged the mitochondrial structure in intestinal epithelial cells\nand liver cells. The 16S rDNA sequencing data showed that all five\nMOF NPs significantly altered the dominant microorganisms in the zebrafish\nintestine. The microbial markers of intestinal inflammation, Proteobacteria (Aeromonas, Plesiomonas, and Legionella), were significantly increased in the\nFe-MOF, ZIF-8, Zr-MOF, and Cu-MOF treatment groups. Metabolomics results\nindicated that the levels of inflammatory promoting factors (Leukotriene\nE4, 20-hydroxyeicosatetraenoic acid) in arachidonic acid metabolism\nwere decreased, and the levels of inflammatory suppressing factors\n(8,9-epoxyeicosatrienoic acid) were increased. Metabolites related\nto oxidative stress, such as glutamine, pyridoxamine, and l-glutamic acid in vitamin B6 metabolism and other signaling pathways,\nwere significantly reduced. Overall, these results suggest that the\ndifferent MOF NPs had widely varying toxicity to zebrafish, and further\nattention should be paid to the toxicity of MOF NPs in the real environment.