MoS2 Nanosheets-Cyanobacteria Interaction: Reprogrammed Carbon and Nitrogen Metabolism

Effects of zeolite imidazole frameworks on rice seedlings (Oryza sativa L.): Phytotoxicity, transformation, and bioaccumulation

Zeolite imidazole frameworks (ZIFs), a class of the metal organic framework, have been extensively studied in environmental applications. However, their environmental fate and potential ecological impact on plants remain unknown. Here, we investigated the phytotoxicity, transformation, and bioaccumulation processes of two typical ZIFs (ZIF-8 and ZIF-67) in rice (Oryza sativa L.) under hydroponic conditions. ZIF-8 and ZIF-67 in the concentration of 50 mg/L decreased root and shoot dry weight maximally by 55.2% and 27.5%, 53.5% and 37.5%, respectively. The scanning electron microscopy (SEM) imaging combined with X-ray diffraction (XRD) patterns revealed that ZIFs on the root surface gradually collapsed and transformed into nanosheets with increasing cultivation time. The fluorescein isothiocyanate (FITC) labeled ZIFs were applied to trace the uptake and translocation of ZIFs in rice. The results demonstrated that the transformed ZIFs were mainly distributed in the intercellular spaces of rice root, while they cannot be transported to culms and leaves. Even so, the Co and Zn contents of rice roots and shoots in the ZIFs treated groups were increased by 1145% and 1259%, 145% and 259%, respectively, compared with the control groups. These findings suggested that the phytotoxicity of ZIFs are primarily attributed to the transformed ZIFs and to a less extent, the metal ions and their ligands, and they were internalized by rice root and increased the Co and Zn contents of shoots. This study reported the transformation of ZIFs and their biological effectiveness in rice, highlighting the potential environmental hazards and risks of ZIFs to crop plants.

Algal extracellular polymeric substance compositions drive the binding characteristics, affinity, and phytotoxicity of graphene oxide in water

Graphene oxide (GO, a popular 2D nanomaterial) poses great potential in water treatment arousing considerable attention regarding its fate and risk in aquatic environments. Extracellular polymeric substances (EPS) exist widely in water and play critical roles in biogeochemical processes. However, the influences of complex EPS fractions on the fate and risk of GO remain unknown in water. This study integrates fluorescence excitation-emission matrix-parallel factor, two-dimensional correlation spectroscopy, and biolayer interferometry studies on the binding characteristics and affinity between EPS fractions and GO. The results revealed the preferential binding of fluorescent aromatic protein-like component, fulvic-like component, and non-fluorescent polysaccharide in soluble EPS (S-EPS) and bound EPS (B-EPS) on GO via π-π stacking and electrostatic interaction that contributed to a higher adsorption capacity of S-EPS on GO and weaker affinity than of B-EPS. Moreover, the EPS fractions drive the morphological and structural alterations, and the attenuated colloid stability of GO in water. Notably, GO-EPS induced stronger phytotoxicity (e.g., photosynthetic damage, and membrane lipid remodeling) compared to pristine GO. Metabolic and functional lipid analysis further elucidated the regulation of amino acid, carbohydrate, and lipid metabolism contributed to the persistent phytotoxicity. This work provides insights into the roles and mechanisms of EPS fractions composition in regulating the environmental fate and risk of GO in natural water.

Redox and Energy Homeostasis Enabled by Photocatalytic Material-Microbial Interfaces

Material-microbial interfaces offer a promising future in sustainable and efficient chemical-energy conversions, yet the impacts of these artificial interfaces on microbial metabolisms remain unclear. Here, we conducted detailed proteomic and metabolomic analyses to study the regulations of microbial metabolism induced by the photocatalytic material-microbial interfaces, especially the intracellular redox and energy homeostasis, which are vital for sustaining cell activity. First, we learned that the materials have a heavier weight in perturbing microbial metabolism and inducing distinctive biological pathways, like the expression of the metal-resisting system, than light stimulations. Furthermore, we observed that the materials-microbe interfaces can maintain the delicate redox balance and the energetic status of the microbial cells since the intracellular redox cofactors and energy currencies show stable levels as naturally inoculated microbes. These observations ensure the possibility of energizing microbial activities with artificial materials-microbe interfaces for diverse applications and also provide guides for future designs of materials-microbe hybrids to guard microbial activities.

Revisiting Solar Energy Flow in Nanomaterial-Microorganism Hybrid Systems

Nanomaterial-microorganism hybrid systems (NMHSs), integrating semiconductor nanomaterials with microorganisms, present a promising platform for broadband solar energy harvesting, high-efficiency carbon reduction, and sustainable chemical production. While studies underscore its potential in diverse solar-to-chemical energy conversions, prevailing NMHSs grapple with suboptimal energy conversion efficiency. Such limitations stem predominantly from an insufficient systematic exploration of the mechanisms dictating solar energy flow. This review provides a systematic overview of the notable advancements in this nascent field, with a particular focus on the discussion of three pivotal steps of energy flow: solar energy capture, cross-membrane energy transport, and energy conversion into chemicals. While key challenges faced in each stage are independently identified and discussed, viable solutions are correspondingly postulated. In view of the interplay of the three steps in affecting the overall efficiency of solar-to-chemical energy conversion, subsequent discussions thus take an integrative and systematic viewpoint to comprehend, analyze and improve the solar energy flow in the current NMHSs of different configurations, and highlighting the contemporary techniques that can be employed to investigate various aspects of energy flow within NMHSs. Finally, a concluding section summarizes opportunities for future research, providing a roadmap for the continued development and optimization of NMHSs.

Nano-sized polystyrene and magnetite collectively promote biofilm stability and resistance due to enhanced oxidative stress response

Despite the growing prevalence of nanoplastics in drinking water distribution systems, the collective influence of nanoplastics and background nanoparticles on biofilm formation and microbial risks remains largely unexplored. Here, we demonstrate that nano-sized polystyrene modified with carboxyl groups (nPS) and background magnetite (nFe3O4) nanoparticles at environmentally relevant concentrations can collectively stimulate biofilm formation and prompt antibiotic resistance. Combined exposure of nPS and nFe3O4 by P. aeruginosa biofilm cells stimulated intracellular reactive oxidative species (ROS) production more significantly compared with individual exposure. The resultant upregulation of quorum sensing (QS) and c-di-GMP signaling pathways enhanced the biosynthesis of polysaccharides by 50 %- 66 % and increased biofilm biomass by 36 %- 40 % relative to unexposed control. Consistently, biofilm mechanical stability (measured as Young's modulus) increased by 7.2-9.1 folds, and chemical stress resistance (measured with chlorine disinfection) increased by 1.4-2.0 folds. For P. aeruginosa, the minimal inhibitory concentration of different antibiotics also increased by 1.1-2.5 folds after combined exposure. Moreover, at a microbial community-wide level, metagenomic analysis revealed that the combined exposure enhanced the multi-species biofilm's resistance to chlorine, enriched the opportunistic pathogenic bacteria, and promoted their virulence and antibiotic resistance. Overall, the enhanced formation of biofilms (that may harbor opportunistic pathogens) by nanoplastics and background nanoparticles is an overlooked phenomenon, which may jeopardize the microbial safety of drinking water distribution systems.

The colloidal stability of molybdenum disulfide nanosheets in different natural surface waters: Combined effects of water chemistry and light irradiation

With the increasing production and application, more molybdenum disulfide (MoS2) nanosheets could be released into environment. The aggregation and dispersion of MoS2 nanosheets profoundly impact their transport and transformation in the aquatic environment. However, the colloidal stability of MoS2 remains largely unknown in natural surface waters. This study investigated the colloidal stability of MoS2 nanosheets in six natural surface waters affected by both light irradiation and water chemistry. Compared to that of the pristine MoS2 nanosheets, the colloidal stability of MoS2 photoaged in ultrapure water declined. Light irradiation induced the formation of Mo-O bonds, the release of SO42- species, and the decrease in 1T/2H ratio, which reduced negative charge and enhanced hydrophobicity. However, the colloidal stability of MoS2 photoaged in natural surface waters was increased relative to that in ultrapure water not only for the smaller extent of photochemical transformation but more importantly the surface modification by water chemistry. Furthermore, the colloidal stability of MoS2 photoaged in natural surface waters followed the order of sea water > lake water > river water. The abundant cations (e.g., Ca2+ and Mg2+) in sea water facilitated the covalent grafting (S-C bonds) of more dissolved organic matter (DOM) on MoS2 via charge screening and cation bridging, thus inducing stronger electrostatic repulsion and steric effect to stabilize nanosheets. The crucial role of the covalent grafting of DOM was further confirmed by the positive correlation between the critical coagulation concentration values and S-C ratios (R2 = 0.82, p < 0.05). Our results highlighted the dominant role of water chemistry than light irradiation in dictating the colloidal stability of MoS2 photoaged in natural surface waters, which provided new insight into the environmental behavior of MoS2 in aquatic environment.

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.

Nitrogen Forms Regulate the Response of Microcystis aeruginosa to Nanoplastics at Environmentally Relevant Nitrogen Concentrations

As essential primary producers, cyanobacteria play a major role in global carbon and nitrogen cycles. Though the influence of nanoplastics on the carbon metabolism of cyanobacteria is well-studied, little is known about how nanoplastics affect their nitrogen metabolism, especially under environmentally relevant nitrogen concentrations. Here, we show that nitrogen forms regulated growth inhibition, nitrogen consumption, and the synthesis and release of microcystin (MC) in Microcystis aeruginosa exposed to 10 μg/mL amino-modified polystyrene nanoplastics (PS-NH2) with a particle size of 50 nm under environmentally relevant nitrogen concentrations of nitrate, ammonium, and urea. We demonstrate that PS-NH2 inhibit M. aeruginosa differently in nitrate, urea, and ammonium, with inhibition rates of 51.87, 39.70, and 36.69%, respectively. It is caused through the differences in impairing cell membrane integrity, disrupting redox homeostasis, and varying nitrogen transport pathways under different nitrogen forms. M. aeruginosa respond to exposure of PS-NH2 by utilizing additional nitrogen to boost the production of amino acids, thereby enhancing the synthesis of MC, extracellular polymeric substances, and membrane phospholipids. Our results found that the threat of nanoplastics on primary producers can be regulated by the nitrogen forms in freshwater ecosystems, contributing to a better understanding of nanoplastic risks under environmentally relevant conditions.

UV-A radiation increases biomass yield by enhancing energy flow and carbon assimilation in the edible cyanobacterium Nostoc sphaeroides

Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth's surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.

A New Type of Quantum Fertilizer (Silicon Quantum Dots) Promotes the Growth and Enhances the Antioxidant Defense System in Rice Seedlings by Reprogramming the Nitrogen and Carbon Metabolism

To promote the growth and yield of crops, it is necessary to develop an effective silicon fertilizer. Herein, a new type of 2 nm silicon quantum dot (SiQD) was developed, and the phenotypic, biochemical, and metabolic responses of rice seedlings treated with SiQDs were investigated. The results indicated that the foliar application of SiQDs could significantly improve the growth of rice seedlings by increasing the uptake of nutrient elements and activating the antioxidative defense system. Furthermore, metabolomics revealed that the supply of SiQDs could significantly up-regulate several antioxidative metabolites (oxalic acid, maleic acid, glycine, lysine, and proline) by reprogramming the nitrogen- and carbon-related biological pathways. The findings provide a new strategy for developing an effective and promising quantum fertilizer in agriculture.

Dynamic Transformation of Nano-MoS2 in a Soil-Plant System Empowers Its Multifunctionality on Soybean Growth

Molybdenum disulfide (nano-MoS2) nanomaterials have shown great potential for biomedical and catalytic applications due to their unique enzyme-mimicking properties. However, their potential agricultural applications have been largely unexplored. A key factor prior to the application of nano-MoS2 in agriculture is understanding its behavior in a complex soil-plant system, particularly in terms of its transformation. Here, we investigate the distribution and transformation of two types of nano-MoS2 (MoS2 nanoparticles and MoS2 nanosheets) in a soil-soybean system through a combination of synchrotron radiation-based X-ray absorption near-edge spectroscopy (XANES) and single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS). We found that MoS2 nanoparticles (NPs) transform dynamically in soil and plant tissues, releasing molybdenum (Mo) and sulfur (S) that can be incorporated gradually into the key enzymes involved in nitrogen metabolism and the antioxidant system, while the rest remain intact and act as nanozymes. Notably, there is 247.9 mg/kg of organic Mo in the nodule, while there is only 49.9 mg/kg of MoS2 NPs. This study demonstrates that it is the transformation that leads to the multifunctionality of MoS2, which can improve the biological nitrogen fixation (BNF) and growth. Therefore, MoS2 NPs enable a 30% increase in yield compared to the traditional molybdenum fertilizer (Na2MoO4). Excessive transformation of MoS2 nanosheets (NS) leads to the overaccumulation of Mo and sulfate in the plant, which damages the nodule function and yield. The study highlights the importance of understanding the transformation of nanomaterials for agricultural applications in future studies.

Earthworm Coelomocyte Internalization of MoS2 Nanosheets: Multiplexed Imaging, Molecular Profiling, and Computational Modeling

Fully understanding the cellular uptake and intracellular localization of MoS2 nanosheets (NSMoS2) is a prerequisite for their safe applications. Here, we characterized the uptake profile of NSMoS2 by functional coelomocytes of the earthworm Eisenia fetida. Considering that vacancy engineering is widely applied to enhance the NSMoS2 performance, we assessed the potential role of such atomic vacancies in regulating cellular uptake processes. Coelomocyte internalization and lysosomal accumulation of NSMoS2 were tracked by fluorescent labeling imaging. Cellular uptake inhibitors, proteomics, and transcriptomics helped to mechanistically distinguish vacancy-mediated endocytosis pathways. Specifically, Mo ions activated transmembrane transporter and ion-binding pathways, entering the coelomocyte through assisted diffusion. Unlike molybdate, pristine NSMoS2 (P-NSMoS2) induced protein polymerization and upregulated gene expression related to actin filament binding, which phenotypically initiated actin-mediated endocytosis. Conversely, vacancy-rich NSMoS2 (V-NSMoS2) were internalized by coelomocytes through a vesicle-mediated and energy-dependent pathway. Mechanistically, atomic vacancies inhibited mitochondrial transport gene expression and likely induced membrane stress, significantly enhancing endocytosis (20.3%, p < 0.001). Molecular dynamics modeling revealed structural and conformational damage of cytoskeletal protein caused by P-NSMoS2, as well as the rapid response of transport protein to V-NSMoS2. These findings demonstrate that earthworm functional coelomocytes can accumulate NSMoS2 and directly mediate cytotoxicity and that atomic vacancies can alter the endocytic pathway and enhance cellular uptake by reprogramming protein response and gene expression patterns. This study provides an important mechanistic understanding of the ecological risks of NSMoS2.

Two-dimensional molybdenum disulfide nanosheets evoke nitric oxide-dependent antibacterial effects

Nanomaterials are currently being explored as novel antimicrobial agents. In this study, we first investigated the ability of two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets to trigger neutrophil extracellular traps (NETs) using neutrophil-differentiated HL-60 cells as well as primary human peripheral blood neutrophils. We then addressed whether the MoS2 nanosheets themselves function as antibacterial agents. We found that MoS2 and Na2MoO4 both triggered NETs, as evidenced by the quantification of neutrophil elastase (NE) activity and immunofluorescence staining of extracellular NE, as well as scanning electron microscopy. The release of NETs was found to be nitric oxide (NO)-dependent. We also found that the MoS2 nanosheets but not the soluble salt prompted acellular NO production in the presence of NaNO2. The acellular generation of NO, suggestive of nanozyme properties of the MoS2 nanosheets, was demonstrated by electron paramagnetic resonance analysis. Electrochemical analysis using cyclic voltammetry confirmed the redox transition of the MoS2 nanosheets. Finally, MoS2 nanosheets inhibited the growth of Escherichia coli in the presence of sodium nitrate. Taken together, MoS2 nanosheets triggered cellular effects as well as acellular antibacterial effects, and we provided evidence for nitrite reductase-like properties of MoS2.

Efficient Semi-Artificial Photosynthesis of Ethylene by a Self-Assembled InP-Cyanobacterial Biohybrid System

Biomanufacturing of ethylene is particularly important for modern society. Cyanobacterial cells are able to photosynthesize various valuable chemicals. A promising platform for next-generation biomanufacturing, the semiconductor-cyanobacterial hybrid systems are capable of enhancing the solar-to-chemical conversion efficiency. Herein, the native ethylene-producing capability of a filamentous cyanobacterium Nostoc sphaeroides is confirmed experimentally. The self-assembly characteristic of N. sphaeroides is exploited to facilitate its interaction with InP nanomaterial, and the resulting biohybrid system gave rise to further elevated photosynthetic ethylene production. Based on chlorophyll fluorescence measurement and metabolic analysis, the InP nanomaterial-augmented photosystem I activity and enhanced ethylene production metabolism of biohybrid cells are confirmed, the mechanism underlying the material-cell energy transduction as well as nanomaterial-modulated photosynthetic light and dark reactions are established. This work not only demonstrates the potential application of semiconductor-N. sphaeroides biohybrid system as a good platform for sustainable ethylene production but also provides an important reference for future studies to construct and optimize nano-cell biohybrid systems for efficient solar-driven valuable chemical production.

Differential toxicity of various mineral nanoparticles to Synechocystis sp.: With and without ciprofloxacin

Mineral nanoparticles (M-NPs) are ubiquitous in aquatic environments, but their potential harms to primary producers and impacts on the toxicity of coexisting pollutants are largely unknown. Herein, the toxicity mechanisms of various M-NPs (i.e., SiO2, Fe2O3, Al2O3, and TiO2 NPs) to Synechocystis sp. in absence and presence of ciprofloxacin (CIP) were comprehensively investigated. The heteroaggregation of cells and M-NPs can hinder substrate transfer or light acquisition. The attraction between Synechocystis sp. and M-NPs increased in the order of SiO2 < Fe2O3 < Al2O3 ≈ TiO2 NPs. Therefore, SiO2 and Fe2O3 NPs exerted slight effects on physiology and proteome of Synechocystis sp.. Al2O3 NPs with the rod-like shape caused physical damage to cells. Differently, TiO2 NPs with photocatalytic activities provided photogenerated electrons for Synechocystis sp., promoting photosynthesis and the Calvin cycle for CO2 fixation. SiO2, Fe2O3, and Al2O3 NPs alleviated the toxicity of CIP in an adsorption-depended manner. Conversely, the combination of CIP and TiO2 NPs exerted more pronounced toxic effects compared to their individuals, and CIP disturbed the extracellular electron transfer from TiO2 NPs to cells. The findings highlight the different effects of TiO2 NPs from other M-NPs on cyanobacteria, either alone or in combination with CIP, and improve the understanding of toxic mechanisms of M-NPs.

Review of Marine Cyanobacteria and the Aspects Related to Their Roles: Chemical, Biological Properties, Nitrogen Fixation and Climate Change

Marine cyanobacteria are an ancient group of photosynthetic microbes dating back to 3.5 million years ago. They are prolific producers of bioactive secondary metabolites. Over millions of years, natural selection has optimized their metabolites to possess activities impacting various biological targets. This paper discusses the historical and existential records of cyanobacteria, and their role in understanding the evolution of marine cyanobacteria through the ages. Recent advancements have focused on isolating and screening bioactive compounds and their respective medicinal properties, and we also discuss chemical property space and clinical trials, where compounds with potential pharmacological effects, such as cytotoxicity, anticancer, and antiparasitic properties, are highlighted. The data have shown that about 43% of the compounds investigated have cytotoxic effects, and around 8% have anti-trypanosome activity. We discussed the role of different marine cyanobacteria groups in fixing nitrogen percentages on Earth and their outcomes in fish productivity by entering food webs and enhancing productivity in different agricultural and ecological fields. The role of marine cyanobacteria in the carbon cycle and their outcomes in improving the efficiency of photosynthetic CO2 fixation in the chloroplasts of crop plants, thus enhancing the crop plant's yield, was highlighted. Ultimately, climate changes have a significant impact on marine cyanobacteria where the temperature rises, and CO2 improves the cyanobacterial nitrogen fixation.

Coupled Lipidomics and Digital Pathology as an Effective Strategy to Identify Novel Adverse Outcome Pathways in Eisenia fetida Exposed to MoS2 Nanosheets and Ionic Mo

Molybdenum disulfide (MoS₂) nanosheets are increasingly applied in several fields, but effective and accurate strategies to fully characterize potential risks to soil ecosystems are lacking. We introduce a coelomocyte-based in vivo exposure strategy to identify novel adverse outcome pathways (AOPs) and molecular endpoints from nontransformed (NTMoS₂) and ultraviolet-transformed (UTMoS₂) MoS₂ nanosheets (10 and 100 mg Mo/L) on the earthworm Eisenia fetida using nontargeted lipidomics integrated with transcriptomics. Machine learning-based digital pathology analysis coupled with phenotypic monitoring was further used to establish the correlation between lipid profiling and whole organism effects. As an ionic control, Na₂MoO₄ exposure significantly reduced (61.2-79.5%) the cellular contents of membrane-associated lipids (glycerophospholipids) in earthworm coelomocytes. Downregulation of the unsaturated fatty acid synthesis pathway and leakage of lactate dehydrogenase (LDH) verified the Na₂MoO₄-induced membrane stress. Compared to conventional molybdate, NTMoS₂ inhibited genes related to transmembrane transport and caused the differential upregulation of phospholipid content. Unlike NTMoS₂, UTMoS₂ specifically upregulated the glyceride metabolism (10.3-179%) and lipid peroxidation degree (50.4-69.4%). Consequently, lipolytic pathways were activated to compensate for the potential energy deprivation. With pathology image quantification, we report that UTMoS₂ caused more severe epithelial damage and intestinal steatosis than NTMoS₂, which is attributed to the edge effect and higher Mo release upon UV irradiation. Our results reveal differential AOPs involving soil sentinel organisms exposed to different Mo forms, demonstrating the potential of liposome analysis to identify novel AOPs and furthermore accurate soil risk assessment strategies for emerging contaminants.

Construction of Bio-TiO2/Algae Complex and Synergetic Mechanism of the Acceleration of Phenol Biodegradation

Microalgae have been widely employed in water pollution treatment since they are eco-friendly and economical. However, the relatively slow treatment rate and low toxic tolerance have seriously limited their utilization in numerous conditions. In light of the problems above, a novel biosynthetic titanium dioxide (bio-TiO₂ NPs)-microalgae synergetic system (Bio-TiO₂/Algae complex) has been established and adopted for phenol degradation in the study. The great biocompatibility of bio-TiO₂ NPs ensured the collaboration with microalgae, improving the phenol degradation rate by 2.27 times compared to that with single microalgae. Remarkably, this system increased the toxicity tolerance of microalgae, represented as promoted extracellular polymeric substances EPS secretion (5.79 times than single algae), and significantly reduced the levels of malondialdehyde and superoxide dismutase. The boosted phenol biodegradation with Bio-TiO₂/Algae complex may be attributed to the synergetic interaction of bio-TiO₂ NPs and microalgae, which led to the decreased bandgap, suppressed recombination rate, and accelerated electron transfer (showed as low electron transfer resistance, larger capacitance, and higher exchange current density), resulting in increased light energy utilization rate and photocatalytic rate. The results of the work provide a new understanding of the low-carbon treatment of toxic organic wastewater and lay a foundation for further remediation application.

The co-occurrent microplastics and nano-CuO showed antagonistic inhibitory effects on bacterial denitrification: Interaction of pollutants and regulations on functional genes

The wide occurrence of microplastics (MPs) and nanoparticles resulted in their inevitable coexistence in environment. However, the joint effects of these two types of particulate emerging contaminants on denitrification have seldomly been investigated. Herein, non-biodegradable polyvinyl chloride, polypropylene, polyethylene and biodegradable polyhydroxyalkanoate (PHA) MPs were chosen to perform the co-occurrent effects with nano copper oxide (nano-CuO). Both the nano-CuO and MPs inhibited the denitrification process, and biodegradable PHA-MPs showed severer inhibition than non-biodegradable MPs. However, the presence of MPs significantly alleviated the inhibition of nano-CuO, suggesting an antagonistic effect. Other than MPs decreasing copper ion release from nano-CuO, MPs and nano-CuO formed agglomerations and induced lower levels of oxidative stress compared to individual exposure. Transcriptome analysis indicated that the co-occurrent MPs and nano-CuO induced different regulation on denitrifying genes (e. g. nar and nor) compared to individual ones. Also, the expressions of genes involved in denitrification-associated metabolic pathways, including glycolysis and NADH electron transfer, were down-regulated by nano-CuO or MPs, but exhibiting recovery under the co-occurrent conditions. This study firstly discloses the antagonistic effect of nano-CuO and MPs on environmental process, and these findings will benefit the systematic evaluation of MPs environmental behavior and co-occurrent risk with other pollutants.

Physicochemical properties of nanosized biochar regulated by heat treatment temperature dictates algal responses: From the perspective of fatty acid metabolism

Nanosized biochar (NBC) is an important fraction of biochar (BC) as it can exert nano-scale effects on aquatic organisms, attracting increasing research attention. However, effects of different physicochemical properties of NBC on biological responses at the metabolic and gene expression level are not comprehensively understood. Here, biological effects of NBCs pyrolyzed at different heat treatment temperatures (HTTs, 350-700 °C) were evaluated using freshwater algae Chlorella vulgaris, from the perspectives of growth and fatty acid (FA) profile changes. NBC pyrolyzed at 700 °C (N700) induced the greatest algal growth inhibition and oxidative stress than N350 and N500. In addition, NBC exposure to 50 mg/L increased saturated and monounsaturated FAs, along with a decrease in polyunsaturated FAs (PUFAs). Exposure to NBC also significantly influenced the expression of key FA metabolism genes (3fad, sad, kasi and accd), demonstrating the potential role of reactive oxygen species-mediated PUFA reduction accompanied by increased membrane permeability in algal toxicity upon NBC exposure. The observed differences in response to N700 were attributed to its smaller particle size and higher abundance of -COOH. These findings reveal the underlying mechanisms in the algal response to NBCs and provide valuable guidance for the safe design and application of BC materials.

Surface Defects Regulate the in Vivo Bioenergetic Response of Earthworm Eisenia fetida Coelomocytes to Molybdenum Disulfide Nanosheets

Two-dimensional molybdenum disulfide (2D MoS₂) nanomaterials are seeing increased use in several areas, and this will lead to their inevitable release into soils. Surface defects can occur on MoS₂ nanosheets during synthesis or during environmental aging processes. The mechanisms of MoS₂ nanosheet toxicity to soil invertebrates and the role of surface defects in that toxicity have not been fully elucidated. We integrated traditional toxicity end points, targeted energy metabolomics, and transcriptomics to compare the mechanistic differences in the toxicity of defect-free and defect-rich MoS₂ nanosheets (DF-MoS₂ and DR-MoS₂) to Eisenia fetida using a coelomocyte-based in vivo assessment model. After organism-level exposure to DF-MoS₂ for 96 h at 10 and 100 mg Mo/L, cellular reactive oxygen species (ROS) levels were elevated by 25.6-96.6% and the activity of mitochondrial respiratory electron transport chain (Mito-RETC) complex III was inhibited by 9.7-19.4%. The tricarboxylic acid cycling and glycolysis were also disrupted. DF-MoS₂ preferentially up-regulated subcellular component motility processes related to microtubules and caused mitochondrial fission. Unlike DF-MoS₂, DR-MoS₂ triggered an increased degree of mitochondrial fusion, as well as more severe oxidative stress. The activities of Mito-RETC complexes (I, III, IV, V) associated with oxidative phosphorylation were significantly inhibited by 22.8-68.6%. Meanwhile, apoptotic pathways were activated upon DR-MoS₂ exposure, which together with the depolarization of mitochondrial membrane potential, mediated significant apoptosis. In turn, genes related to cellular homeostasis and energy release were up-regulated to compensate for DR-MoS₂-induced energy deprivation. Our study indicates that MoS₂ nanosheets have nanospecific effects on E. fetida and also that the role of surface defects from synthesis or that accumulate from environmental impacts needs to be fully considered when evaluating the toxicity of these 2D materials.

Effects of WS2 Nanosheets on N2-fixing Cyanobacteria: ROS overproduction, cell membrane damage, and cell metabolic reprogramming

The ecotoxicity of tungsten disulfide (WS₂) nanomaterials remains unclear so far. Here, the toxicity of WS₂ nanosheets on N₂-fixing cyanobacteria (Nostoc sphaeroides) was evaluated. Specifically, Nostoc were cultivated in media spiked with different concentrations of WS₂ nanosheets (0, 0.05, 0.1 and 0.5 mg/L) for 96 h. Relative to unexposed cells, WS₂ nanosheets at 0.5 mg/L significantly decreased cell density, content of total sugar and protein by 10.9 %, 0.43 %, and 6.1 %, respectively. Gas chromatography-mass spectrometry (GC-MS)-based metabolomics revealed that WS₂ nanosheets exposure altered the metabolite profile of Nostoc in a dose-dependent manner. Energy metabolism related pathways, including the Calvin-Benson-Bassham (CBB) cycle and tricarboxylic acid (TCA) cycle, were significantly inhibited. In addition, WS₂ nanosheets exposure resulted in downregulation (20-40 %) of S-containing amino acids (cystine, methionine, and cysteine) and sulfuric acid. Additionally, fatty acids and antioxidant-related compounds (formononetin, catechin, epigallocatechin, dehydroascorbic acid, and alpha-tocopherol) in Nostoc were drastically decreased by 4-50 % upon exposure to WS₂ nanosheets, which implies oxidative stress induced by the nanomaterials. Biochemical assays for reactive oxygen species (ROS) and malondialdehyde (MDA) confirmed that WS₂ nanosheets triggered ROS overproduction and induced lipid peroxidation. Taken together, WS₂ exposure perturbed carbon (C), nitrogen (N), and sulfate (S) metabolism of Nostoc, which may influence C, N, and S cycling, given the important roles of cyanobacteria in these processes. These results highlight the need for caution in the application and environmental release of WS₂ nanomaterials to prevent unintended environmental impacts due to their potential ecotoxicity.

Lighting Up Agricultural Sustainability in the New Era through Nanozymology: An Overview of Classifications and Their Agricultural Applications

With the concept of sustainable agriculture receiving increasing attention from humankind, nanozymes, nanomaterials with enzyme-like activity but higher environmental endurance and longer-term stability than natural enzymes, have enabled agricultural technologies to be reformative, economic, and portable. Benefiting from their multiple catalytic activities and renewable nanocharacteristics, nanozymes can shine in agricultural scenarios using enzyme engineering and nanoscience, acting as sustainable toolboxes to improve agricultural production and reduce the risk to agricultural systems. Herein, we comprehensively discuss the classifications of nanozymes applied in current agriculture, including peroxidase-like, oxidase-like, catalase-like, superoxide dismutase-like, and laccase-like nanozymes, as well as their biocatalytic mechanisms. Especially, different applications of nanozymes in agriculture are deeply reviewed, covering crop protection and nutrition, agroenvironmental remediation and monitoring, and agroproduct quality monitoring. Finally, the challenges faced by nanozymes in agricultural applications are proposed, and we expect that our review can further enhance agricultural sustainability through nanozymology.

Toxicological effects of WS2 nanomaterials on rice plants and associated soil microbes

As an important member of transition-metal dichalcogenides family, tungsten disulfides nanomaterials (WS₂ NMs) have a wide range of applications. To date, their environmental risks remain largely unknown. In this study, rice plants were grown in soil amended with different concentrations (0, 10, and 100 mg/kg) of WS₂ NMs for 4 weeks. WS₂ NMs at 100 mg/kg significantly increased MDA (malondialdehyde) content and decreased total antioxidant capacities of leaves, indicating the oxidative response induced by WS₂ NMs. Meanwhile, WS₂ NMs at 100 mg/kg significantly decreased root biomass compared to control, indicating the negative impacts of WS₂ NMs on plant growth. While exposure to 100 mg/kg WS₂ NMs significantly increased soil bioavailable Cu, Fe, Zn, and Olsen-P, and increased the content of Cu, Fe, Zn, and P in rice leaves. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis showed that W was taken up by rice roots and translocated into leaves. The impact of WS₂ on soil microbial communities was evaluated by 16S rRNA gene sequencing. WS₂ NMs at 100 mg/kg significantly decreased soil microbial diversity, as indicated by decreased Shannon index. In addition, 100 mg/kg WS₂ shifted the soil microbial profile, the relative abundance of the phylum Acidobacteriota decreased, and Actinobacteriota increased. Taken together, the soil microbial community's diversity and composition have been altered upon exposure to 100 mg/kg WS₂ NMs. The results of this study provide some basic information regarding the environmental behavior and phytotoxicity of WS₂ NMs, which is valuable for safe use of WS₂ NMs.

Therapeutic Delivery of Nanoscale Sulfur to Suppress Disease in Tomatoes: In Vitro Imaging and Orthogonal Mechanistic Investigation

Nanoscale sulfur can be a multifunctional agricultural amendment to enhance crop nutrition and suppress disease. Pristine (nS) and stearic acid coated (cS) sulfur nanoparticles were added to soil planted with tomatoes (Solanum lycopersicum) at 200 mg/L soil and infested with Fusarium oxysporum. Bulk sulfur, ionic sulfate, and healthy controls were included. Orthogonal end points were measured in two greenhouse experiments, including agronomic and photosynthetic parameters, disease severity/suppression, mechanistic biochemical and molecular end points including the time-dependent expression of 13 genes related to two S bioassimilation and pathogenesis-response, and metabolomic profiles. Disease reduced the plant biomass by up to 87%, but nS and cS amendment significantly reduced disease as determined by area-under-the-disease-progress curve by 54 and 56%, respectively. An increase in planta S accumulation was evident, with size-specific translocation ratios suggesting different uptake mechanisms. In vivo two-photon microscopy and time-dependent gene expression revealed a nanoscale-specific elemental S bioassimilation pathway within the plant that is separate from traditional sulfate accumulation. These findings correlate well with time-dependent metabolomic profiling, which exhibited increased disease resistance and plant immunity related metabolites only with nanoscale treatment. The linked gene expression and metabolomics data demonstrate a time-sensitive physiological window where nanoscale stimulation of plant immunity will be effective. These findings provide mechanistic understandings of nonmetal nanomaterial-based suppression of plant disease and significantly advance sustainable nanoenabled agricultural strategies to increase food production.

Two-Dimensional Transition Metal Dichalcogenides Trigger Trained Immunity in Human Macrophages through Epigenetic and Metabolic Pathways

Trained immunity is a recently described phenomenon whereby cells of the innate immune system undergo long-term epigenetic and/or metabolic reprogramming following a short-term interaction with microbes or microbial products. Here, it is shown that 2D transition metal dichalcogenides (TMDs) trigger trained immunity in primary human monocyte-derived macrophages. First, aqueous dispersions of 2D crystal formulations of MoS₂ and WS₂ are tested, and no cytotoxicity is found despite avid uptake of these materials by macrophages. However, when macrophages are pre-exposed to TMDs, followed by a resting period, this causes a marked modulation of immune-specific gene expression upon subsequent challenge with a microbial agent (i.e., bacterial lipopolysaccharides). Specifically, MoS₂ triggers trained immunity through an epigenetic pathway insofar as the histone methyltransferase inhibitor methylthioadenosine reverses these effects. Furthermore, MoS₂ triggers an elevation of cyclic adenosine monophosphate (cAMP) levels in macrophages and increased glycolysis is also evidenced in cells subjected to MoS₂ training, pointing toward a metabolic rewiring of the cells. Importantly, it is observed that MoS₂ triggers the upregulation of Mo-dependent enzymes in macrophages, thus confirming that Mo is bioavailable in these cells. In conclusion, MoS₂ is identified as a novel inducer of trained immunity. Thus, TMDs could potentially be harnessed as immunomodulatory agents.

Metabolic alterations in alga Chlamydomonas reinhardtii exposed to nTiO2 materials

Nano-sized titanium dioxide (nTiO₂) is one of the most commonly used materials, however the knowledge about the molecular basis for metabolic and physiological changes in phytoplankton is yet to be explored. In the present study we use a combination of targeted metabolomics, transcriptomics and physiological response studies to decipher the metabolic perturbation in green alga Chlamydomonas reinhardtii exposed for 72 h to increasing concentrations (2, 20, 100 and 200 mg L⁻¹) of nTiO₂ with primary sizes of 5, 15 and 20 nm. Results show that the exposure to all three nTiO₂ materials induced perturbation of the metabolism of amino acids, nucleotides, fatty acids, tricarboxylic acids, antioxidants but not in the photosynthesis. The alterations of the most responsive metabolites were concentration and primary size-dependent despite the significant formation of micrometer-size aggregates and their sedimentation. The metabolic perturbations corroborate the observed physiological responses and transcriptomic results and confirmed the importance of oxidative stress as a major toxicity mechanism for nTiO₂. Transcriptomics revealed also an important influence of nTiO₂ treatments on the transport, adenosine triphosphate binding cassette transporters, and metal transporters, suggesting a perturbation in a global nutrition of the microalgal cell, which was most pronounced for exposure to 5 nm nTiO₂. The present study provides for the first-time evidence for the main metabolic perturbations in green alga C. reinhardtii exposed to nTiO₂ and helps to improve biological understanding of the molecular basis of these perturbations.

Combination of transcriptomics, metabolomics and physiology studies highlighted the nanoparticle size- and concentration-dependent disturbance in algal metabolism induced by nTiO₂.