Toxicity evaluation of bulk and nanosheet MoS2 catalysts using battery bioassays

Interactions of monolayer molybdenum disulfide sheets with metalloid antimony in aquatic environment: Adsorption, transformation, and joint toxicity

The tremendous application potentiality of transitional metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2) nanosheets, will unavoidably lead to increasing release into the environment, which could influence the fate and toxicity of co-existed contaminants. The present study discovered that 59.8 % of trivalent antimony [Sb(III)] was transformed by MoS2 to pentavalent Sb [Sb(V)] in aqueous solutions under light illumination, which was due to hole oxidation on the nanosheet surfaces. A synergistic toxicity between MoS2 and Sb(III, V) to algae (Chlorella vulgaris) was observed, as demonstrated by the lower median-effect concentrations of MoS2 + Sb(III)/Sb(V) (13.1 and 20.9 mg/L, respectively) than Sb(III)/Sb(V) (38.8 and 92.5 mg/L, respectively) alone. Particularly, MoS2 at noncytotoxic doses notably increased the bioaccumulation of Sb(III, V) in algae, causing aggravated oxidative damage, photosynthetic inhibition, and structural alterations. Metabolomics indicated that oxidative stress and membrane permeabilization were primarily associated with down-regulated amino acids involved in glutathione biosynthesis and unsaturated fatty acids. MoS2 co-exposure remarkably decreased the levels of thiol antidotes (glutathione and phytochelatins) and aggravated the inhibition on energy metabolism and ATP synthesis, compromising the Sb(III, V) detoxification and efflux. Additionally, extracellular P was captured by the nanosheets, also contributing to the uptake of Sb(V). Our findings emphasized the nonignorability of TMDs even at environmental levels in affecting the ecological hazard of metalloids, providing insight into comprehensive safety assessment of TMDs.

Recent advances in catalytic oxidation of VOCs by two-dimensional ultra-thin nanomaterials

Catalytic oxidation, an end-of-pipe treatment technology for effectively purifying volatile organic compounds (VOCs), has received widespread attention. The crux of catalytic oxidation lies in the development of efficient catalysts, with their optimization necessitating a comprehensive analysis of the catalytic reaction mechanism. Two-dimensional (2D) ultra-thin nanomaterials offer significant advantages in exploring the catalytic oxidation mechanism of VOCs due to their unique structure and properties. This review classifies strategies for regulating catalytic properties and typical applications of 2D materials in VOCs catalytic oxidation, in addition to their characteristics and typical characterization techniques. Furthermore, the possible reaction mechanism of 2D Co-based and Mn-based oxides in the catalytic oxidation of VOCs is analyzed, with a special focus on the synergistic effect between oxygen and metal vacancies. The objective of this review is to provide valuable references for scholars in the field.

Sustainable biofuel synthesis from non-edible oils: a mesoporous ZSM-5/Ni/Pt catalyst approach

This work examines the hydrodeoxygenation (HDO) activity of non-edible oils using a high surface area catalyst. The HDO activity was thoroughly examined and contrasted using the high surface area catalyst Ni/Pt-ZSM-5 as well as other supports like MCM-48 and H-beta. Ni/Pt bimetals supported on mesoporous ZSM-5 were created via reverse order impregnation to facilitate HDO of non-edible oils. Techniques such as XRD, FT-IR, BET, HR-TEM, HR-SEM, TPD, and TGA were used to characterize the produced catalysts. The synthesized catalysts considerably influenced the hydrodeoxygenation activities for the synthesis of lengthy chain hydrocarbons in a stainless-steel reactor with a high-pressure fixed bed between 300 and 375 °C under 10-40 bar hydrogen pressure. High levels of Ni/Pt-ZSM-5 acidity, textural, and H2 consumption qualities were discovered. Distributions of the products were also reviewed, along with comparisons of the structure-activity connections.

Deoxynivalenol (DON)-Triggered Dual-Color Composite Probe Based on Gold Nanoclusters for Simultaneous Imaging of DON and miR-34a in Living Cells

Deoxynivalenol (DON) is a mycotoxin secreted by Fusarium species, posing great harm to food safety and human health. Therefore, it is of great significance to study its toxic effects and mechanism. miR-34a is a representative biomarker during the process of DON-induced apoptosis. Herein, a DON-triggered dual-color composite probe was constructed for simultaneous imaging of DON and miR-34a in living cells. The aptamer blocks the recognition sequence of miR-34a to realize DON-triggered cell imaging. The specific binding of DON with its aptamer and HCR induced by miR-34a resulted in the recovery of fluorescence of the dual-color Au NCs. Under the optimal conditions, the correlation between the relative fluorescence intensities of dual-color Au NCs showed good linear relationships with the logarithm of DON and miR-34a concentration, respectively. With the increase in DON concentration (0-20 μg/mL) and stimulation time (0-12 h), the fluorescence of dual-color Au NCs gradually recovered. This dual-color Au NCs composite probe can realize simultaneous detection of DON and miR-34a induced by DON, which is significant for verifying the cytotoxic mechanism of DON.

Extracellular polymeric substances altered the physicochemical properties of molybdenum disulfide nanomaterials to mitigate its toxicity to Chlorella vulgaris

Although the toxic effects of two-dimensional nanomaterials (2D-NMs) have been widely reported, the influence of extracellular polymeric substances (EPS) on the environmental fate and risk of 2D-NMs in aquatic environments is largely unknown, and the processes and mechanisms involved remain to be revealed. Herein, we investigated the impact of EPS secreted by microalgae (Chlorella vulgaris (C. vulgaris)) on the environmental transformation and risk of molybdenum disulfide (MoS2). We found that the attachment of EPS increased the thickness of MoS2 (from 2 nm to 5 nm), changed it from a monolayer sheet to a fuzzy multilayer structure, and promoted the formation of defects on MoS2. The blue-shift of the peak associated with the plasmon resonances in the 1 T phase and the generation of electron-hole pairs suggested that EPS altered the surface electronic structure of MoS2. EPS interacted mainly with the S atoms on the 1 T phase, and the attachment of EPS promoted the oxidation of MoS2. The reduction in hydrodynamic diameter (Dh) and the decrease in zeta potential indicated that EPS inhibited the agglomeration behavior of MoS2 and enhanced its dispersion and stability in aqueous media. Notably, EPS reduced the generation of free radicals (superoxide anion (•O2-), singlet oxygen (1O2), and hydroxyl radicals (•OH-)). Furthermore, EPS mitigated the toxicity of MoS2 to C. vulgaris, such as attenuated reduction in biomass and chlorophyll content. Compared to pristine MoS2, MoS2 + BG11 + EPS exhibited weaker oxidative stress, membrane damage and lipid peroxidation. The adsorption of EPS on MoS2 surface reduced the attachment sites of MoS2, making MoS2 less likely to be enriched on the cell surface. The findings have significant contribution for understanding the interactions between EPS and MoS2 in aquatic ecosystems, providing scientific guidance for risk assessment of 2D-NMs.

Interactions of molybdenum disulfide nanosheets with wheat plants under changing environments: More than meets the eye?

Molybdenum disulfide (MoS2) nanosheets are being increasingly employed in various applications. It is therefore imperative to assess their potential environmental implications in a changing world, particularly in the context of global warming. Here, we assessed the effects of MoS2 nanosheets on wheat Triticum aestivum L. under today's typical climatic conditions (22 °C) and future climatic conditions (30 °C), respectively. The results showed that MoS2 nanosheets (10 and 100 Mo mg/L) did not significantly affect wheat plant growth, root morphological traits, and chlorophyll fluorescence, regardless of dose and temperature. However, the metabolic processes were significantly altered in T. aestivum upon exposure to individual MoS2 nanosheets and to a combination of MoS2 nanosheets and future global warming. As a non-specific protective strategy, the wheat plants that were under stress conditions maintained the stability of cell membranes and thus relieved cell injury by accumulating more glycerophospholipids. Warming additionally influenced the nitrogen and carbon pool reallocation in wheat root. MoS2 nanosheets mainly depleted a range of antioxidant metabolites involved in phenylpropanoid biosynthesis and taurine and hypotaurine metabolism, while warming activated vitamin B6 cofactors related to vitamin B6 metabolism. Metabolites involved in glutathione metabolism were uniquely upregulated while most metabolites associated with nucleotide metabolisms were uniquely downregulated in combination-treated wheat. Overall, wheat plants regulated a wide range of growth-related processes, including carbohydrate, amino acids, lipid, vitamins, and nucleotide metabolism, to maintain optimal metabolite pool sizes and eventually global metabolic homeostasis upon different stress conditions. Our findings provide novel insights into MoS2 nanosheets-mediated crop responses under global warming.

Exposure to MoS2 nanosheets or bulk activated Kruppel-like factor 4 in 3D Caco-2 spheroids in vitro and mouse intestines in vivo

MoS₂ nanosheets (NSs) are novel 2D nanomaterials (NMs) being used in many important fields. Recently, we proposed the need to evaluate the influences of NMs on Kruppel-like factors (KLFs) even if these materials are relatively biocompatible. In this study, we investigated the influences of MoS₂ NSs or bulk on KLF4 signaling pathway in 3D Caco-2 spheroids in vitro and mouse intestines in vivo. Through the analysis of our previous RNA-sequencing data, we found that exposure to MoS₂ NSs or bulk activated KLF4 expression in 3D Caco-2 spheroids. Consistently, these materials also activated KLF4-related gene ontology (GO) terms and down-regulated a panel of KLF4-downstream genes. To verify these findings, we repeatedly exposed mice to MoS₂ NSs or bulk materials via intragastrical administration (1 mg/kg bodyweight, once a day, for 4 days). It was shown that oral exposure to these materials decreased bodyweight, leading to relatively higher organ coefficients. As expected, exposure to both types of materials increased Mo elements as well as other trace elements, such as Zn, Fe, and Mn in mouse intestines. The exposure also induced morphological changes of intestines, such as shortening of intestinal villi and decreased crypt depth, which may result in decreased intestinal lipid staining. Consistent with RNA-sequencing data, we found that material exposure increased KLF4 protein staining in mouse intestines and decreased two KLF4 downstream proteins, namely extracellular signal-regulated kinase (ERK) and serine/threonine kinase (AKT). We concluded that MoS₂ materials were capable to activate KLF4-signaling pathway in intestines both in vivo and in vitro.

Ex Situ Characterization of 1T/2H MoS2 and Their Carbon Composites for Energy Applications, a Review

The growing interest in the development of next-generation net zero energy systems has led to the expansion of molybdenum disulfide (MoS₂) research in this area. This activity has resulted in a wide range of manufacturing/synthesis methods, controllable morphologies, diverse carbonaceous composite structures, a multitude of applicable characterization techniques, and multiple energy applications for MoS₂. To assess the literature trends, 37,347 MoS₂ research articles from Web of Science were text scanned to classify articles according to energy application research and characterization techniques employed. Within the review, characterization techniques are grouped under the following categories: morphology, crystal structure, composition, and chemistry. The most common characterization techniques identified through text scanning are recommended as the base fingerprint for MoS₂ samples. These include: scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Similarly, XPS and Raman spectroscopy are suggested for 2H or 1T MoS₂ phase confirmation. We provide guidance on the collection and presentation of MoS₂ characterization data. This includes how to effectively combine multiple characterization techniques, considering the sample area probed by each technique and their statistical significance, and the benefit of using reference samples. For ease of access for future experimental comparison, key numeric MoS₂ characterization values are tabulated and major literature discrepancies or currently debated characterization disputes are highlighted.

Adaptive Triboelectric Nanogenerators for Long-Term Self-Treatment: A Review

Triboelectric nanogenerators (TENGs) were initially invented as an innovative energy-harvesting technology for scavenging mechanical energy from our bodies or the ambient environment. Through adaptive customization design, TENGs have also become a promising player in the self-powered wearable medical market for improving physical fitness and sustaining a healthy lifestyle. In addition to simultaneously harvesting our body's mechanical energy and actively detecting our physiological parameters and metabolic status, TENGs can also provide personalized medical treatment solutions in a self-powered modality. This review aims to cover the recent advances in TENG-based electronics in clinical applications, beginning from the basic working principles of TENGs and their general operation modes, continuing to the harvesting of bioenergy from the human body, and arriving at their adaptive design toward applications in chronic disease diagnosis and long-term clinical treatment. Considering the highly personalized usage scenarios, special attention is paid to customized modules that are based on TENGs and support complex medical treatments, where sustainability, biodegradability, compliance, and bio-friendliness may be critical for the operation of clinical systems. While this review provides a comprehensive understanding of TENG-based clinical devices that aims to reach a high level of technological readiness, the challenges and shortcomings of TENG-based clinical devices are also highlighted, with the expectation of providing a useful reference for the further development of such customized healthcare systems and the transfer of their technical capabilities into real-life patient care.

Tailoring Morphology and Properties of Tight Utrafiltration Membranes by Two-Dimensional Molybdenum Disulfide for Performance Improvement

To enhance the permeation and separation performance of the polyethersulfone (PES) tight ultrafiltration (TUF) membrane, two-dimensional molybdenum disulfide (MoS2) was applied as a modifier in low concentrations. The influence of different concentrations of MoS2 (0, 0.25, 0.50, 1.00, and 1.50 wt%) on TUF membranes was investigated in terms of morphology, mechanical strength properties, permeation, and separation. The results indicate that the blending of MoS2 tailored the microstructure of the membrane and enhanced the mechanical strength property. Moreover, by embedding an appropriate amount of MoS2 into the membrane, the PES/MoS2 membranes showed improvement in permeation and without the sacrifice of the rejection of bovine serum protein (BSA) and humic acid (HA). Compared with the pristine membrane, the modified membrane embedded with 0.5 wt% MoS2 showed a 36.08% increase in the pure water flux, and >99.6% rejections of BSA and HA. This study reveals that two-dimensional MoS2 can be used as an effective additive to improve the performance and properties of TUF membranes for water treatment.

MoS2 and MoS2 Nanocomposites for Adsorption and Photodegradation of Water Pollutants: A Review

The need for fresh and conveniently treated water has become a major concern in recent years. Molybdenum disulfide (MoS₂) nanomaterials are attracting attention in various fields, such as energy, hydrogen production, and water decontamination. This review provides an overview of the recent developments in MoS₂-based nanomaterials for water treatment via adsorption and photodegradation. Primary attention is given to the structure, properties, and major methods for the synthesis and modification of MoS₂, aiming for efficient water-contaminant removal. The combination of MoS₂ with other components results in nanocomposites that can be separated easily or that present enhanced adsorptive and photocatalytic properties. The performance of these materials in the adsorption of heavy metal ions and organic contaminants, such as dyes and drugs, is reviewed. The review also summarizes current progress in the photocatalytic degradation of various water pollutants, using MoS₂-based nanomaterials under UV-VIS light irradiation. MoS₂-based materials showed good activity after several reuse cycles and in real water scenarios. Regarding the ecotoxicity of the MoS₂, the number of studies is still limited, and more work is needed to effectively evaluate the risks of using this nanomaterial in water treatment.

MoS2 based nanomaterials: Advanced antibacterial agents for future

Bacterial infections are yet another serious threat to human health. Misuse or overuse of conventional antibiotics has led to the arrival of various super resistant bacteria along with many serious side effects to human body. In this exigent circumstance, the use of nanomaterial based antibacterial agents is one of the most appropriate solutions to fight against bacteria thereby causing an inhibition to bacterial proliferation. Recent studies show that, due to the large surface area, high biocompatibility, strong near-infrared (NIR) absorption and low cytotoxicity, molybdenum disulphide (MoS₂), an extraordinary member in the transition metal dichalcogenides (TMDs) is extensively explored in the obliteration of many drug resistant bacteria, photothermal therapy and drug delivery. MoS₂ based nanomaterials can effectively prevent bacterial growth through many mechanisms. Through this review, we have tried to provide an inclusive knowledge on the recent progress of antibacterial studies in MoS₂ based nanomaterials including MoS₂ nanosheets, nanoflowers, quantum dot (QD), hybrid nanocomposites and polymer nanocomposites. Moreover, toxicity of MoS₂ based nanomaterials is described at the end of the review.

Impact of algal extracellular polymeric substances on the environmental fate and risk of molybdenum disulfide in aqueous media

Molybdenum disulfide (MoS₂) poses great potential in water treatment as a popular transition metal dichalcogenide, arousing considerable concern regarding its fates and risk in aquatic environments. This study revealed that the interplay with extracellular polymeric substances (EPS) of freshwater algae significantly changed the properties and toxicity of MoS₂ to aquatic fish. The predominant binding of aromatic compounds, polysaccharides, and carboxyl-rich proteins in EPS on the 1T polymorph of MoS₂ via hydrophilic effects and the preferential adsorption of carboxylic groups contributed to morphological alterations, structural disorders (band gap and phase alterations), and the attenuated aggregation of MoS₂ in aqueous solutions. Electron charge transfer and n-π* interactions with EPS decreased the catalytic activity of MoS₂ by inhibiting its capability of generating reactive intermediates. The dissolution of MoS₂ slowed down after interacting with EPS (from 0.089 to 0.045 mg/L per day) owing to rapid initial oxidation (i.e., forming Mo-O bond) and carbon grafting. Notably, the morphological and structural alterations after EPS binding alleviated the toxicity (e.g., malformation and oxidative stress) of MoS₂ to infantile zebrafish. Our findings provide insights into the environmental fate and risk of MoS₂ by ubiquitous EPS in natural waters, serving as valuable information while developing water treatment processes accordingly.