Dispersible MoS 2 micro-sheets induced a proinflammatory response and apoptosis in the gills and liver of adult zebrafish.

Molybdenum disulfide (MoS 2 ), one of the next-generation two-dimensional materials (2DMs), has attracted increasing attention due to its unique physicochemical properties. However, the aquatic toxicity of dispersible MoS 2 is still unknown. Herein, we synthesized chitosan functionalized MoS 2 (CS-MoS 2 ) micro-sheets with a satisfying water-dispersible performance. The average length and width of the as-prepared CS-MoS 2 micro-sheets were 5.04 μm and 3.12 μm, respectively, and they had a pristine 2H polymorph. The toxicity of CS-MoS 2 micro-sheets was assessed by investigating the organs, gills and liver of adult zebrafish. We found that exposure to high concentrations of CS-MoS 2 micro-sheets (10 mg L -1 and 20 mg L -1 ) led to lamellar fusions in the gills, and significant localized lesions, such as peripheral nuclei and vacuole formation, in the liver. In addition, treatment with 20 mg L -1 CS-MoS 2 micro-sheets suppressed gene expression of antioxidant enzymes ( e.g. , CAT and GPx1a gene) and induced the expression levels of the proinflammatory response and apoptosis ( e.g. , IL-1β, IL-6, and AIF gene) in gill and liver tissues. Further, reactive oxygen species (ROS) were generated upon treatment with 20 mg L -1 CS-MoS 2 micro-sheets in both organs. To the best of our knowledge, this is the first investigation of the aquatic toxicity of dispersible MoS 2 in zebrafish, and further highlights the potential environmental risk of MoS 2 .