Oxidation suppression during hydrothermal phase reversion allows synthesis of monolayer semiconducting MoS<sub>2</sub> in stable aqueous suspension

Wang, Zhongying; Zhang, Yin-Jia; Liu, Muchun; Peterson, Andrew A.; Hurt, Robert H.

doi:10.1039/c7nr01193h

Cited by 38 publications

(45 citation statements)

References 40 publications

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“…Recent literature has begun to address the stability of 2D materials under conditions relevant to environmental and biological effects. 6,19,23–25 MoS 2 has been experimentally confirmed to undergo oxidative dissolution, 19,26 in agreement with thermodynamic predictions. 6,19 Graphene-based materials are also thermodynamically unstable to oxidation, but like most other carbons show very slow oxidation kinetics, and have been reported to require reactive oxygen species or oxidative enzymes for degradation over laboratory time scales.…”

Section: Introductionsupporting

confidence: 75%

Biodissolution and cellular response to MoO₃nanoribbons and a new framework for early hazard screening for 2D materials

Gray

Browning

Wang

et al. 2018

Environ. Sci.: Nano

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Two-dimensional (2D) materials are a broad class of synthetic ultra-thin sheet-like solids whose rapid pace of development motivates systematic study of their biological effects and safe design. A challenge for this effort is the large number of new materials and their chemical diversity. Recent work suggests that many 2D materials will be thermodynamically unstable and thus non-persistent in biological environments. Such information could inform and accelerate safety assessment, but experimental data to confirm the thermodynamic predictions is lacking. Here we propose a framework for early hazard screening of nanosheet materials based on biodissolution studies in reactive media, specially chosen for each material to match chemically feasible degradation pathways. Simple dissolution and in vitro tests allow grouping of nanosheet materials into four classes: A, potentially biopersistent; B: slowly degradable (>24–48 hours); C, biosoluble with potentially hazardous degradation products; and D, biosoluble with low-hazard degradation products. The proposed framework is demonstrated through an experimental case study on MoO3 nanoribbons, which have a dual 2D / 1D morphology and have been reported to be stable in aqueous stock solutions. The nanoribbons are shown to undergo rapid dissolution in biological simulant fluids and in cell culture, where they elicit no adverse responses up to 100μg ml−1 dose. These results place MoO3 nanoribbons in Class D, and assigns them a low priority for further nanotoxicology testing. We anticipate use of this framework could accelerate the risk assessment for the large set of new powdered 2D nanosheet materials, and promote their safe design and commercialization.

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Section: Introductionsupporting

confidence: 75%

Biodissolution and cellular response to MoO₃nanoribbons and a new framework for early hazard screening for 2D materials

Gray

Browning

Wang

et al. 2018

Environ. Sci.: Nano

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“…Net negative charge in layered manganese oxide materials (the so-called phyllomanganates) such as delta-MnO 2 has been associated with Mn vacancies or Mn 3+ lattice substitutions for Mn 4+ . [93,94] A distinctive feature of MnO 2 nanomaterials is their biochemical reactivity. They are highly insoluble in water, but have reduction potentials within the range of the cellular redox potential.…”

Section: The Mno 2 -Biological Interfacementioning

confidence: 99%

“…This framework uses in vitro dissolution studies in reactive simulants to classify 2D materials into one of four categories for rationale hazard assessment and prioritization. While oxidative and hydrolytic degradation routes are common, [20,94] MnO 2 is one of the few 2D materials proposed to follow a reductive degradation route, [18] and the first reductive case study in the Gray et al framework. [20] Human exposure to MnO 2 nanosheets in the form of aerosols or dry powders is a primary concern in occupational settings.…”

Section: Implications For Nanosafetymentioning

confidence: 99%

Chemical and Colloidal Dynamics of MnO₂ Nanosheets in Biological Media Relevant for Nanosafety Assessment

Gray

Browning

Vaslet

et al. 2020

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Many layered crystal phases can be exfoliated or assembled into ultrathin 2D nanosheets with novel properties not achievable by particulate or fibrous nanoforms. Among these 2D materials are manganese dioxide (MnO 2 ) nanosheets, which have applications in batteries, catalysts, and biomedical probes. A novel feature of MnO 2 is its sensitivity to chemical reduction leading to dissolution and Mn 2+ release. Biodissolution is critical for nanosafety assessment of 2D materials, but the timing and location of MnO 2 biodissolution in environmental or occupational exposure scenarios are poorly understood. This work investigates the chemical and colloidal dynamics of MnO 2 nanosheets in biological media for environmental and human health risk assessment. MnO 2 nanosheets are insoluble in most aqueous phases, but react with strong and weak reducing agents in biological fluid environments. In vitro, reductive dissolution can be slow enough in cell culture media for MnO 2 internalization by cells in the form of intact nanosheets, which localize in vacuoles, react to deplete intracellular glutathione, and induce cytotoxicity that is likely mediated by intracellular Mn 2+ release. The results are used to classify MnO 2 nanosheets within a new hazard screening framework for 2D materials, and the implications of MnO 2 transformations for nanotoxicity testing and nanosafety assessment are discussed.

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“…This forms oxides which can significantly degrade the performance in energy and tribology related applications [7]. Even 'defect-free' TMDs oxidize at the basal plane when exposed to atomic oxygen found in low earth orbit environment [8][9][10][11], which can severely impact their use as lubricants in space technology. In addition, the presence of oxygen on the surface of TMDs is a critical issue in micro-and opto-electronic applications, where high electrical conductivity and carrier mobility is required.…”

Section: Introductionmentioning

confidence: 99%

Pyrene Coating Transition Metal Disulfides as Protection from Photooxidation and Environmental Aging

et al. 2020

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Environmental degradation of transition metal disulfides (TMDs) is a key stumbling block in a range of applications. We show that a simple one-pot non-covalent pyrene coating process protects TMDs from both photoinduced oxidation and environmental aging. Pyrene is immobilized non-covalently on the basal plane of exfoliated MoS2 and WS2. The optical properties of TMD/pyrene are assessed via electronic absorption and fluorescence emission spectroscopy. High-resolution scanning transmission electron microscopy coupled with electron energy loss spectroscopy confirms extensive pyrene surface coverage, with density functional theory calculations suggesting a strongly bound stable parallel-stacked pyrene coverage of ~2–3 layers on the TMD surfaces. Raman spectroscopy of exfoliated TMDs while irradiating at 0.9 mW/4 μm2 under ambient conditions shows new and strong Raman bands due to oxidized states of Mo and W. Yet remarkably, under the same exposure conditions TMD/pyrene remain unperturbed. The current findings demonstrate that pyrene physisorbed on MoS2 and WS2 acts as an environmental barrier, preventing oxidative surface reactions in the TMDs catalyzed by moisture, air, and assisted by laser irradiation. Raman spectroscopy confirms that the hybrid materials stored under ambient conditions for two years remained structurally unaltered, corroborating the beneficial role of pyrene for not only hindering oxidation but also inhibiting aging.

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Oxidation suppression during hydrothermal phase reversion allows synthesis of monolayer semiconducting MoS₂ in stable aqueous suspension

Cited by 38 publications

References 40 publications

Biodissolution and cellular response to MoO₃nanoribbons and a new framework for early hazard screening for 2D materials

Biodissolution and cellular response to MoO₃nanoribbons and a new framework for early hazard screening for 2D materials

Chemical and Colloidal Dynamics of MnO₂ Nanosheets in Biological Media Relevant for Nanosafety Assessment

Pyrene Coating Transition Metal Disulfides as Protection from Photooxidation and Environmental Aging

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Oxidation suppression during hydrothermal phase reversion allows synthesis of monolayer semiconducting MoS2 in stable aqueous suspension

Cited by 38 publications

References 40 publications

Biodissolution and cellular response to MoO3nanoribbons and a new framework for early hazard screening for 2D materials

Biodissolution and cellular response to MoO3nanoribbons and a new framework for early hazard screening for 2D materials

Chemical and Colloidal Dynamics of MnO2 Nanosheets in Biological Media Relevant for Nanosafety Assessment

Pyrene Coating Transition Metal Disulfides as Protection from Photooxidation and Environmental Aging

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Product

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Oxidation suppression during hydrothermal phase reversion allows synthesis of monolayer semiconducting MoS₂ in stable aqueous suspension

Biodissolution and cellular response to MoO₃nanoribbons and a new framework for early hazard screening for 2D materials

Biodissolution and cellular response to MoO₃nanoribbons and a new framework for early hazard screening for 2D materials

Chemical and Colloidal Dynamics of MnO₂ Nanosheets in Biological Media Relevant for Nanosafety Assessment