Dispersible MoS2 micro-sheets induced a proinflammatory response and apoptosis in the gills and liver of adult zebrafish

Abstract

Molybdenum disulfide (MoS₂), 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 MoS₂ is still unknown. Herein, we synthesized chitosan functionalized MoS₂ (CS-MoS₂) micro-sheets with a satisfying water-dispersible performance. The average length and width of the as-prepared CS-MoS₂ micro-sheets were 5.04 μm and 3.12 μm, respectively, and they had a pristine 2H polymorph. The toxicity of CS-MoS₂ micro-sheets was assessed by investigating the organs, gills and liver of adult zebrafish. We found that exposure to high concentrations of CS-MoS₂ 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-MoS₂ 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-MoS₂ micro-sheets in both organs. To the best of our knowledge, this is the first investigation of the aquatic toxicity of dispersible MoS₂ in zebrafish, and further highlights the potential environmental risk of MoS₂.