Nanoholes\nRegulate the Phytotoxicity of Single-Layer\nMolybdenum Disulfide

Abstract

Single-layer molybdenum disulfide\n(SLMoS₂) are applied\nas a hot 2D nanosheet in various fields involving water treatments.\nBoth intentional design and environmental or biological processes\ninduce many nanoholes in SLMoS₂. However, the effects of\nnanoholes on the environmental stability and ecotoxicity of SLMoS₂ remain largely unknown. The present work discovered that\nvisible-light irradiation induced nanoholes (diameters, approximately\n20 nm) in the plane of SLMoS₂, with irregular edges and\nincreased interplanar crystal spacing. The ratios of Mo to S in pristine\nand transformed SLMoS₂ were 0.53 and 0.33, respectively.\nAfter 96 h exposure at concentrations from 0.1 to 1 mg/L, the above\nnanoholes promoted algal division, induced a stress-response hormesis,\ndecreased the generation of •OH, and mitigated the cell shrinkage\nand wall rupture of <i>Chlorella vulgaris</i> induced by\nSLMoS₂. In terms of stress response, the nanohole-bearing\nSLMoS₂ induced fewer vacuoles and polyphosphate bodies\nof <i>Chlorella vulgaris</i> than the pristine form. Metabolomic\nanalysis revealed that nanoholes perturbed the metabolisms of energy,\ncarbohydrates, and fatty acids. This work proposes that nanoholes\ncause obvious effects on the environmental fate and ecotoxicity of\nSLMoS₂ and that the environmental risks of engineered nanomaterials\nshould be reevaluated using nanohole-bearing rather than pristine\nforms for testing.