Effects of dispersible MoS₂ nanosheets and Nano-silver coexistence on the metabolome of yeast

As a new rising star in the post-graphene two-dimensional materials (2DMs), molybdenum disulfide (MoS₂) attracts increasing attentions and is widely applied. However, the chemical and toxicological interaction between MoS₂ and other co-contaminants is still poorly understood. Nano-silver (N-Ag) is the most commonly used nanomaterial in commercial products and distributed widely in the environment. Herein, we investigated the effects of chitosan functionalized MoS₂ (CS-MoS₂) nanosheets, a water-dispersible form of MoS₂, on the microbial toxicity of N-Ag. We found that the incorporation of CS-MoS₂ nanosheets attenuated the oxidative stress induced by N-Ag on yeast cells, while caused more membrane stress. In addition, the inhibition of N-Ag on the metabolic activities of yeast cells could be attenuated by CS-MoS₂ nanosheets as well. The coexistence of N-Ag and CS-MoS₂ nanosheets mainly perturbed the amino acid-related metabolic pathways in yeast cells, and phosphoric acid was a potential nanotoxicity biomarker. We further found that CS-MoS₂ nanosheets dramatically absorbed the Ag ion released from N-Ag, which might be responsible for its attenuation effect on the microbial toxicity of N-Ag. Our findings provide more new insights for the ecotoxicity evaluation of MoS₂ and other 2DMs.