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The environmental transformations of nanomaterials are correlated with their behaviors and ecological risks. The applications of single-layer molybdenum disulfide (SLMoS2) have rapidly developed in environmental fields, but the potential transformations and biological effects of SLMoS2 remain largely unknown. This study revealed that humic acid (HA, over 10 mg/L) induced the scrolling of SLMoS2 with light irradiation over a 56-day incubation. The colloidal stability of SLMoS2 increased, and the aggregation ratio decreased from 0.59 ± 0.07 to 0.08 ± 0.01 nm/min after HA hybridization. Besides, compared with pristine SLMoS2, the chemical dissolution rate of SLMoS2 was up to 4.6-fold faster with HA exposure. These results demonstrate that HA affects the environmental fate and transformations of SLMoS2. SLMoS2-HA possessed a significantly widened direct band gap (2.06 eV) compared with that of SLMoS2 (1.8 eV). SLMoS2 acted as an electronic acceptor from HA, resulting in the separation of electron-hole pairs. Consequently, SLMoS2-HA exhibited stronger peroxidase-like catalytic activity, which was approximately 2-fold higher than that of SLMoS2. Moreover, the morphology and layered structure of SLMoS2 changed, and the damage SLMoS2 inflicted on microalgae was significantly reduced. This work provides insights into the behaviors and related biological risks of SLMoS2 in aqueous environments. [ABSTRACT FROM AUTHOR]

The interactions between nanomaterials and plants have attracted increasing attention. However, the systemic stress and recovery patterns of plants in response to nanomaterials and the connections between the molecular responses and the phenotypes remain unclear. Herein, rice was exposed to graphene oxide (GO) nanosheets at 0.01-1.0 mg/L for 7 days under hydroponic exposure, followed by a 7-day post exposure (GO-free). The significant upregulation (p < 0.05) of phenylalanine metabolism, secondary metabolism, and heme peroxidase reflected the stress and recovery patterns of rice roots exposed to GO. GO triggered 27% and more than 50% decreases in hydraulic conductivity and aquaporin gene expression (PIP1-3 and PIP2-2), respectively. The uptake of GO was mediated by aquaporin inhibition. Nanomaterial biotransformation reflected the potential for rice roots to adapt to GO stress. Oxidative stress, especially the downregulation of class III peroxidase mRNAs, were suppressed by GO. Lateral root inhibition, primary root growth, and cell wall synthesis, as forms of resistance to GO stress, were related to the significant (p < 0.05) downregulation of salicylic acid and lignin biosynthesis, as well as the upregulation of jasmonic acid and laccases. The present study helps elucidate the molecular and phenotypic responses of plants to nanomaterials, which are closely linked to their environmental risk assessment. [ABSTRACT FROM AUTHOR]

The article focuses on the health and ecosystem risks of graphene. It discusses several properties of graphene that determines risks including size-size distribution of graphene, corrugation in cell adhesion and pi-bonds inducing nonspecific binding. It highlights the in vitro and in vivo application of tissue engineering devices, electrical sensors and anticancer drugs. It highlights several health risks of graphene including damage of mucus, skin permeation and cell vision.