Sulfur Vacancy Induced by Extracellular Polymeric Substances Increases the Phytotoxicity of Single-Layer Mos2

Two-dimensional transition metal dichalcogenides (TMDCs) nanomaterials have attracted tremendous research interest in various fields, while the effects of eco-corona formation on the transformation mechanisms and ecological risk of TMDCs remain largely unknown. The effect of eco-corona formation on TMDC reactivity was explored using extracellular polymeric substances (EPS) as the eco-corona constituents and single-layer molybdenum disulfide (SLMoS2) as the model TMDC. We found that EPS promoted lattice distortion and the formation of sulfur vacancies on SLMoS2 after aging with EPS during pre-coated process under simulated visible-light irradiation. In addition, EPS-corona induced higher free radicals (especially hyperoxide radicals) photogeneration of SLMoS2. Furthermore, compared to pristine SLMoS2, SLMoS2-EPS exhibited stronger developmental inhibition, oxidative stress, membrane damage, photosynthetic toxicity and metabolic perturbation effects on Chlorella vulgaris. However, the endocytosis pathway (especially macropinocytosis) of SLMoS2 into C. vulgaris was inhibited by EPS. Metabolic and transcriptomic analyses revealed that the enhanced toxicity of SLMoS2-EPS was associated with the downregulation of fatty acid metabolism and transcription related to photosynthesis, respectively. The present work provides mechanistic insights into the roles of the EPS-corona on the environmental transformation and phytotoxicity of TMDCs, which benefit environmental safety assessments and sustainable applications of engineered nanomaterials