es0c02642_si_001.pdf (2.73 MB)
Influence of Size and Phase on the Biodegradation, Excretion, and Phytotoxicity Persistence of Single-Layer Molybdenum Disulfide
journal contribution
posted on 2020-09-07, 07:29 authored by Wei Zou, Xinyu Li, Chonghao Li, Yuanyuan Sun, Xingli Zhang, Caixia Jin, Kai Jiang, Qixing Zhou, Xiangang HuThe
increasing applications of single-layer molybdenum disulfide
(SLMoS2) pose great potential risks associated with environmental
exposure. This study found that metallic-phase SLMoS2 with
nanoscale (N-1T-SLMoS2, ∼400 nm) and microscale
(M-1T-SLMoS2, ∼3.6 μm) diameters at 10–25
mg/L induced significant algal growth inhibition (maximum 72.7 and
74.6%, respectively), plasmolysis, and oxidative damage, but these
alterations were recoverable. Nevertheless, membrane permeability,
chloroplast damage, and chlorophyll biosynthesis reduction were persistent.
By contrast, the growth inhibition (maximum 55.3%) and adverse effects
of nano-sized semiconductive-phase SLMoS2 (N-2H-SLMoS2, ∼400 nm) were weak and easily alleviated after 96
h of recovery. N-1T-SLMoS2 (0.011 μg/h) and N-2H-SLMoS2 (0.008 μg/h) were quickly biodegraded to soluble Mo
compared with M-1T-SLMoS2 (0.004 μg/h) and excreted
by algae. Incomplete biodegradation of SLMoS2 (26.8–43.9%)
did not significantly mitigate its toxicity. Proteomics and metabolomics
indicated that the downregulation of proteins (50.7–99.2%)
related to antioxidants and photosynthesis and inhibition of carbon
fixation and carbohydrate metabolism contributed to the persistent
phytotoxicity. These findings highlight the roles and mechanisms of
the size and phase in the persistent phytotoxicity of SLMoS2, which has potential implications for risk assessment and environmental
applications of nanomaterials.