Magnetic iron-based nanoparticles biogeochemical behavior in soil-plant system: A critical review.

Increasing attention is being given to magnetic iron-based nanoparticles (MINPs) because of their potential environmental benefits. Owing to the earth abundance and high utilization of MINPs, as well as the significant functions of Fe in sustainable agriculture and environmental remediation, an understanding of the environmental fate of MINPs is indispensable. However, there are still knowledge gaps regarding the largely unknown environmental behaviors and fate of MINPs in soil-plant system. Thus, this review summarizes recent literature on the biogeochemical behavior (uptake, transportation, and transformation) of MINPs in soil and plants. The different possible uptake (e.g., foliar and root adsorption) and translocation (e.g., xylem, phloem, symplastic/apoplastic pathway, and endocytosis) pathways are discussed. Furthermore, drivers of MINPs uptake and transportation (e.g., soil characteristics, fertilizer treatments, copresence of inorganic and organic anions, meteorological conditions, and cell wall pores) in both soil and plant environments are summarized. This review also details the physical, chemical, and biological transformations of MINPs in soil-plant system. More importantly, a metadata analysis from the existing literature was employed to investigate the distinction between MINPs and other engineering nanoparticles biogeochemical behavior. In the future, more attention should be given to understanding the behavior of MINPs in soil-plant system and improving the capabilities of predictive models. This review thus highlights the main knowledge gaps regarding MINPs behavior and fate to provide guidance for their safe application in agrochemicals, crop production, and soil health.

Diatomic catalysts for Fenton and Fenton-like reactions: a promising platform for designing/regulating reaction pathways.

The optimization of the single-atom catalyst (SAC) performance has been the hot spot for years. It is widely acknowledged that the incorporation of adjacent single-atom sites (diatomic catalysts (DACs)) can enable synergistic effects, which can be used in cascade catalysis, dual-function catalysis, and performance regulation of intrinsic active sites. DACs have been widely applied in the CO2 reduction reaction (CO2RR), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), etc.; however, their application is limited in Fenton or Fenton-like reactions. This perspective summarizes the most advanced achievements in this field, followed by the proposed opportunities in further research, including regulation of the magnetic moment, inter-atomic distance effect, strain engineering, atomic cluster (AC)/nanoparticle (NP) modification, etc. It is demonstrated that this perspective can contribute to the DAC application in Fenton or Fenton-like reactions with innovative design and mechanisms being put forward.

Iron oxide nanoparticles in the soil environment: Adsorption, transformation, and environmental risk.

Iron oxide nanoparticles (IONPs) have great application potential due to their multifunctional excellence properties, leading to the possibility of their release into soil environments. IONPs exhibit different adsorption properties toward environmental pollutants (e.g., heavy metals and organic compounds), thus the adsorption performance for various contaminants and the molecular interactions at the IONPs-pollutants interface are discussed. After solute adsorption, the change in the environmental behavior of IONPs is an important transformation process in the natural environments. The aggregation, aging process, and chemical/biological transformation of IONPs can be altered by soil solution chemistry, as well as by the presence of dissolved organic matter and microorganisms. Upon exposure to soil environments, IONPs have both positive and negative impacts on soil organisms (e.g., bacteria, plants, nematodes, and earthworms). Moreover, we compared the toxicity of IONPs alone to combined toxicity with environmental pollutants and pristine IONPs to aged IONPs, and the mechanisms of IONPs toxicity at the cellular level are also reviewed. Given the unanswered questions, future research should include prediction and design of IONPs, new characterization technology for monitoring IONPs transformation in soil ecosystems, and further refinement the environmental risk assessment of IONPs. This review will greatly enhance our knowledge of the performance and impact of IONPs in soil systems.

Microplastics Weaken the Adaptability of Cyanobacterium Synechococcus sp. to Ocean Warming.

Ocean warming (OW) caused by anthropogenic activities threatens ocean ecosystems. Moreover, microplastic (MP) pollution in the global ocean is also increasing. However, the combined effects of OW and MPs on marine phytoplankton are unclear. Synechococcus sp., the most ubiquitous autotrophic cyanobacterium, was used to evaluate the response to OW + MPs under two warming scenarios (28 and 32 °C compared to 24 °C). The enhancement of the cell growth rate and carbon fixation under OW were weakened by MP exposure. Specifically, OW + MPs reduced carbon fixation by 10.9 and 15.4% at 28 and 32 °C, respectively. In addition, reduction in photosynthesis pigment contents of Synechococcus sp. under OW was intensified under OW + MPs, supporting the lower growth rate and carbon fixation under OW + MPs. Transcriptome plasticity (the evolutionary and adaptive potential of gene expression in response to changing environments) enabled Synechococcus sp. to develop a warming-adaptive transcriptional profile (downregulation of photosynthesis and CO2 fixation) under OW. Nevertheless, the downregulation of photosynthesis and CO2 fixation were alleviated under OW + MPs to increase responsiveness to the adverse effect. Due to the high abundances of Synechococcus sp. and its contributions to primary production, these findings are important for understanding the effects of MPs on carbon fixation and ocean carbon fluxes under global warming.

The optimized Fenton-like activity of Fe single-atom sites by Fe atomic clusters-mediated electronic configuration modulation.

The performance optimization of isolated atomically dispersed metal active sites is critical but challenging. Here, TiO2@Fe species-N-C catalysts with Fe atomic clusters (ACs) and satellite Fe-N4 active sites were fabricated to initiate peroxymonosulfate (PMS) oxidation reaction. The AC-induced charge redistribution of single atoms (SAs) was verified, thus strengthening the interaction between SAs and PMS. In detail, the incorporation of ACs optimized the HSO5- oxidation and SO5·- desorption steps, accelerating the reaction progress. As a result, the Vis/TiFeAS/PMS system rapidly eliminated 90.81% of 45 mg/L tetracycline (TC) in 10 min. The reaction process characterization suggested that PMS as an electron donor would transfer electron to Fe species in TiFeAS, generating 1O2. Subsequently, the hVB+ can induce the generation of electron-deficient Fe species, promoting the reaction circulation. This work provides a strategy to construct catalysts with multiple atom assembly-enabled composite active sites for high-efficiency PMS-based advanced oxidation processes (AOPs).

Effect of natural soil nanocolloids on the fate and toxicity of cadmium to rice (Oryza sativa L.) roots.

Toxic heavy metals are common contaminants and will most likely interact with ubiquitous natural nanocolloids (Ncs) in the soil environment. However, the effect of soil Ncs on the fate and health risk of cadmium (Cd) have not been well addressed. Here, the interaction between Ncs and Cd is investigated using two-dimensional correlation spectroscopy (2DCOS) combined with synchronous fluorescence and Fourier transform infrared spectroscopy. Our results reveal that Cd binding to the soil Ncs surface is mainly driven through strong hydrophilic effects and π - π interactions, which contribute to a high adsorption capacity (366-612 mg/g) and strong affinity (KL = 4.3-9.7 L/mg) of Cd to soil Ncs. Interestingly, soil Ncs and Cd coexposure can significantly mediate the phytotoxicity (e.g., uptake, root growth, and oxidative stress) of Cd to rice (Oryza sativa L.) roots after 7 days of exposure. At the molecular level, metabolomic analysis reveals that the downregulated metabolic pathways (e.g., isoquinoline alkaloid and aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism) may contribute to the above adverse phytotoxicity. This study provides new insight into the effect of natural Ncs on the fate and health risks of toxic heavy metals in soil environments.

Natural nanocolloids regulate the fate and phytotoxicity of hematite particles in water.

Hematite (the most abundant iron oxide polymorph) is widely detected in the water environment and has attracted considerable attention. Natural nanocolloids (Ncs) exist ubiquitously in surface waters and play critical roles in biogeochemical processes. However, the influences of Ncs on the fate and phytotoxicity of hematite remain unknown. In this study, the infrared absorption spectra coupled with two-dimensional correlation spectroscopy analysis reveal that the specific binding interactions between Ncs and hematite primarily occur via hydrophilic effects and π-π interactions with an increase in the Ncs contact time. Moreover, binding with Ncs slightly promoted the aggregation rates of hematite particles in the BG-11 medium. Interestingly, Ncs remarkably mitigate the phytotoxicity (e.g., growth inhibition, oxidative stress, and mitochondrial toxicity) of nanosized and submicrosized hematite particles to Chlorella vulgaris after a 96 h exposure. The integrating metabolomic and transcriptomic analysis reveals that the regulated urea cycle, amino acids, and fatty acid-related metabolites (e.g., urea, serine, glutamate, and hexadecenoic acid) and genes (e.g., ACY1, CysC, and GLA) contribute to persistent phytotoxicity. This study provides new insights into the roles and mechanisms of natural Ncs in regulating the environmental risk of iron oxide minerals in aqueous media.

Enhanced carbon emission driven by the interaction between functional microbial community and hydrocarbons: An enlightenment for carbon cycle.

Soil microbial communities are usually regarded as one of the key players in the global element cycling. Moreover, an important consequence of oil contamination altering the structure of microbial communities is likely to result in an increased carbon emission. However, understanding of the complex interactions between environmental factors and biological communities is clearly lagging behind. Here it showed that the flux of carbon emissions increased in oil-contaminated soils, up to 13.64 g C·(kg soil)-1·h-1. This phenomenon was mainly driven by the enrichment of rare degrading microorganisms (e.g., Methylosinus, Marinobacter, Pseudomonas, Alcanivorax, Yeosuana, Halomonas and Microbulbifer) in the aerobic layer, rather than the anaerobic layer, which is more conducive to methane formation. In addition, petroleum hydrocarbons and environmental factors are equally important in shaping the structure of microbial communities (the ecological stability) and functional traits (e.g., fatty acid metabolism, lipid metabolism and amino acid metabolism) due to the different ecological sensitivities of microorganisms. Thus, it can be believed that the variability of rare hydrocarbon degrading microorganisms is of greater concern than changes in dominant microorganisms in oil-contaminated soil. Undoubtedly, this study could reveal the unique characterization of bacterial communities that mediate carbon emission and provide evidence for understanding the conversion from carbon stores to carbon gas release in oil-contaminated soils.

Triclosan Reprograms Immunometabolism and Activates the Inflammasome in Human Macrophages.

To gather enough energy to respond to harmful stimuli, most immune cells quickly shift their metabolic profile. This process of immunometabolism plays a critical role in the regulation of immune cell function. Triclosan, a synthetic antibacterial component present in a wide range of consumer items, has been shown to cause immunotoxicity in a number of organisms. However, it is unclear whether and how triclosan impacts immunometabolism. Here, human macrophages were used as model cells to explore the modulatory effect of triclosan on immunometabolism. Untargeted metabolomics using integrated liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) revealed that triclosan changed the global metabolic profile of macrophages. Furthermore, Seahorse energy analysis and 13C isotope-based metabolic flux analysis revealed that triclosan decreased mitochondrial respiratory activity and promoted a metabolic transition from oxidative phosphorylation to glycolysis. Triclosan also polarizes macrophages to the proinflammatory M1 phenotype and activates the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing receptor 3 (NLRP3) inflammasome, which is consistent with triclosan-induced metabolic phenotypic modifications. Collectively, these findings showed that triclosan exposure at micromolar concentrations caused metabolic reprogramming in macrophages, which triggered an inflammatory response. These findings are important for understanding the immunotoxicity caused by triclosan, which is necessary for determining the risk posed by triclosan in the environment.

Integrating FTIR 2D correlation analyses, regular and omics analyses studies on the interaction and algal toxicity mechanisms between graphene oxide and cadmium.

Graphene oxide (GO, a popular 2D graphene-based nanomaterial) has developed quickly and has received considerable attention for its applications in environmental protection and pollutant removal. However, significant knowledge gaps still exist about the interaction characteristic and joint toxicity mechanism of GO and cadmium (Cd) on aquatic organisms. In this study, GO showed a high adsorption capacity (120. 6 mg/g) and strong adsorption affinity (KL = 0.85 L/mg) for Cd2+. Integrating multiple analytical methods (e.g., electron microscopy, Raman spectra, and 2D correlation spectroscopy) revealed that Cd2+ is uniformly adsorbed on the GO surface and edge mainly through cation-π interactions. The combined ecological effects of GO and Cd2+ on Chlorella vulgaris were observed. Cd2+ induced more severe growth inhibition, photosynthesis toxicity, ultrastructure damage and plasmolysis than GO. Interestingly, we found that GO nanosheets could augment the algal toxicity of Cd2+ (e.g., chlorophyll b, mitochondrial membrane damage, and uptake). Transcriptomics and metabolomics further explained the underlying mechanism. The results indicated that the regulation of PSI-, PSII-, and metal transport-related genes (e.g., ABCG37 and ZIP4) and the inhibition of metabolic pathways (e.g., amino acid, fatty acid, and carbohydrate metabolism) were responsible for the persistent phytotoxicity. The present work provides mechanistic insights into the roles of coexisting inorganic pollutants on the environmental fate and risk of GO in aquatic ecosystems.

Pulmonary Fibrosis Induced by CdSe Nanorods and the Therapy with Modified Procyanidinere.

The CdSe nanorod as a one-dimensional nanostructure has an excellent performance in many fields, such as healthcare, new energy, and environmental protection. Thus, it is crucial to investigate its potential adverse health effects prior to their wide exposure. The lung tissue would be the main target organ after CdSe nanorods enter living systems. Here, we showed that pulmonary instillation of CdSe nanorods could decrease the vitality of T-SOD and T-AOC in lung tissues of a rat, increase MDA and hydroxyproline levels and lipid peroxidation products, induce mitochondrial cristae breakage and vacuolization, cause inflammatory responses, and finally induce pulmonary fibrosis. The oral administration of modified procyanidinere could significantly increase the content of antioxidant enzymes, scavenge free radicals, reduce lipid peroxidation, and have protective effects on CdSe nanorods-induced pulmonary fibrosis. The benefit is not only in the early inflammatory stage but also in the later stages of the CdSe nanorods-induced pulmonary fibrosis.

Anthropogenic impacts on the biodiversity and anti-interference ability of microbial communities in lakes.

Lakes are critical for biogeochemical and ecological processes and are sensitive and vulnerable to anthropogenic disturbances, but how and to what extent human activities disturb the biodiversity in lakes remain unknown. Here, we showed the microbial diversity in 46 lakes and assessed the influence of 27 anthropogenic factors. We found that the economic level (e.g., per capita gross domestic product) was strongly negatively correlated (r = -0.97) with bacterial diversity but positively correlated (r = 0.17) with fungal diversity in lakes. The composition of the microbial community significantly changed with increasing economic level. Bacteria are more sensitive than fungi to anthropogenic impacts. Expanding the population size and increasing the economic level may promote the development of fungal diversity but inhibit bacterial diversity. Air quality, urbanization and ozone were negatively correlated with bacterial diversity, and fisheries had a negative correlation with fungal diversity. The anti-interference ability of lake microorganisms in the middle economic level zones (45,000-90,000 yuan/person) was stronger than that in high-level (> 90,000 yuan/person) and low-level (> 45,000 yuan/person) economic zones. Overall, our investigation provides national-scale evidence that changes in the microbial diversity in lakes were related to economic levels.

Direct and Indirect Genotoxicity of Graphene Family Nanomaterials on DNA-A Review.

Graphene family nanomaterials (GFNs), including graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphene quantum dots (GQDs), have manifold potential applications, leading to the possibility of their release into environments and the exposure to humans and other organisms. However, the genotoxicity of GFNs on DNA remains largely unknown. In this review, we highlight the interactions between DNA and GFNs and summarize the mechanisms of genotoxicity induced by GFNs. Generally, the genotoxicity can be sub-classified into direct genotoxicity and indirect genotoxicity. The direct genotoxicity (e.g., direct physical nucleus and DNA damage) and indirect genotoxicity mechanisms (e.g., physical destruction, oxidative stress, epigenetic toxicity, and DNA replication) of GFNs were summarized in the manuscript, respectively. Moreover, the influences factors, such as physicochemical properties, exposure dose, and time, on the genotoxicity of GFNs are also briefly discussed. Given the important role of genotoxicity in GFNs exposure risk assessment, future research should be conducted on the following: (1) developing reliable testing methods; (2) elucidating the response mechanisms associated with genotoxicity in depth; and (3) enriching the evaluation database regarding the type of GFNs, applied dosages, and exposure times.

Nanocolloids, but Not Humic Acids, Augment the Phytotoxicity of Single-Layer Molybdenum Disulfide Nanosheets.

Engineered nanomaterials (ENMs), especially transition metal dichalcogenide (TMDC), have received great attention in recent years due to their advantageous properties and applications in various fields and are inevitably released into the environment during their life cycle. However, the effect of natural nanocolloids, widely distributed in the aquatic environment, on the environmental transformation and ecotoxicity of ENMs remains largely unknown. In this study, the effects of natural nanocolloids were compared to humic acid on the environmental transformation and ecotoxicity of single-layer molybdenum disulfide (SLMoS2), a representative TMDC. SLMoS2 with nanocolloids or humic acid (HA) enhanced their dispersion and Mo ion release in deionized water. Nanocolloids induced growth inhibition, reactive oxygen species (ROS) elevation, and cell permeability. Low-toxicity SLMoS2 combined with nanocolloids will enhance the above adverse effects. SLMoS2-nanocolloids induced serious damage (cell distortion and deformation), SLMoS2 internalization, and metabolic perturbation on Chlorella vulgaris (C. vulgaris). In contrast, the addition of HA induced the growth promotion and lower ROS level, inhibited the internalization of SLMoS2, and mitigated metabolic perturbation on C. vulgaris. This work provides insights into the effect of natural nanocolloids on the behaviors and biological risks of ENMs in aquatic environments, deserving substantial future attention.

Graphene oxide nanosheets mitigate the developmental toxicity of TDCIPP in zebrafish via activating the mitochondrial respiratory chain and energy metabolism.

Graphene oxide (GO), a novel two-dimension carbon nanomaterial, has showed tremendous potential for utilization in intelligent manufacturing and environmental protection. In parallel, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is widely distributed in the water environment and represents a great threat to ecosystem health. However, the related knowledge remained absent regarding the impact of GO on the biological risks of TDCIPP. Herein, GO significantly reduced the mortality and malformation rates of zebrafish induced by TDCIPP maximumly by 28.6% and 41.8%, respectively. Decreased mitochondrial respiratory chain (MRC) enzyme and ATP activity induced by TDCIPP were mitigated by GO. Integrating proteomics and metabolomics revealed TDCIPP obviously induced the downregulation of the proteins and metabolites involved in the cytoskeleton, mitochondrial function, carbohydrate and amino acid metabolism, and the TCA cycle, but the alterations were attenuated by GO. GO primarily promoted MRC activity, carbohydrate metabolism, and fatty acid ß-oxidation, thus activating the energy metabolism of zebrafish and leading to antagonistic effects on the developmental toxicity of TDCIPP. These results provide a novel view on the co-exposure of GO with other pollutants and promote the reconsideration of the environmental risks of GO.

Natural Nanocolloids Mediate the Phytotoxicity of Graphene Oxide.

Nanocolloids (Ncs) are ubiquitous in natural surface waters. However, the effects of Ncs on the fate and ecotoxicity of graphene oxide (GO, a popular engineered nanomaterial (ENM)) remain largely unknown. Ncs exhibit strong adsorption affinity (KL = 1.93 L/mg) and high adsorption capacity (176.2 mg/g) for GO. After Ncs hybridization, GO nanosheets became scrolls, and the aggregation rate of GO decreased. The influence of humic acid and Ncs on GO toxicity was compared. Humic acid mitigated the phytotoxicity of GO. However, GO and GO-Ncs were found to have an envelopment effect on algal cells, and both could enter algal cells. GO-Ncs induced higher reactive oxygen species (ROS) generation, stronger DNA damage and plasmolysis, and more obvious inhibition of photosynthesis compared to GO. Proteomic analysis revealed that photosystem I- and II-related proteins (e.g., E1ZQR2 and E1ZPG5) were regulated more significantly in the GO-Ncs groups than in the GO groups. A combined proteomic and metabolomic analysis showed that inhibition of carbohydrate, fatty acid, and amino acid metabolism contributed to ROS generation. Given the high concentrations and activity of Ncs, the above results highlight the need for reconsideration of the Ncs-mediated environmental behaviors and risks of ENMs and other pollutants.

Widely distributed nanocolloids in water regulate the fate and risk of graphene oxide.

The environmental behaviors and risks associated with graphene oxide (GO, a popular 2D nanomaterial) have attracted considerable attention. GO released to aquatic systems will most likely interact with ubiquitous nanocolloids (Nc) in surface water. However, the effects of Nc on the fate and risk of GO remain largely unknown in water. Herein, the binding of Nc onto GO was investigated via electron microscopy, electron paramagnetic resonance, 2D correlation spectroscopy and biolayer interferometry. The results revealed that electron charge transfers, hydrophilic effects and π-π stacking contributed to a strong affinity (KD = 5.6 nM) and high adsorption capacity (159.8 mg/g) of Nc onto the GO surface. Moreover, GO nanosheets transformed to a scroll morphology or multiple GO particles bridging by Nc, which remarkably reduced the aggregation and sedimentation rates after binding with Nc. Interestingly, co-exposure with Nc greatly alleviated the toxicity (e.g., tail malformation, yolk sac edema and oxidative stress) of GO to zebrafish embryos. Morphological and structural alterations of GO after binding to Nc contributed to the mechanisms for the antagonistic effects on the zebrafish embryos toxicity. The present work provides insights into the environmental fate and risk of GO by ubiquitous Nc in natural water.

Integrating Biolayer Interferometry, Atomic Force Microscopy, and Density Functional Theory Calculation Studies on the Affinity between Humic Acid Fractions and Graphene Oxide.

The interactions between nanoparticles and humic acid (HA) are critical to understanding the environmental risks and applications of nanoparticles. However, the interactions between HA fractions and graphene oxide (GO, a popular carbon nanosheet) at the molecular level remain largely unclear. Four HA fractions with molecular weights ranging from 4.6 to 23.8 kDa were separated, and the large HA fractions presented low oxygen contents and many aromatic structures. The binding constants of the large HA fractions on GO were 2.6- to 3551-fold higher than those of the small HA fractions, while the maximum adsorption capacities of the larger HA fractions onto GO were much higher. Atomic force microscopy (AFM) found that the small and large HA fractions were spread over the center and the edge of the GO nanosheets, respectively. Density functional theory (DFT) simulation and nuclear magnetic resonance spectroscopy confirmed the above phenomena (three adsorption patterns, "vs", "ps", and "pea") and revealed that HA bonded to the GO nanosheets mainly through van der Waals force and π-π interactions. The integrating analysis of binding affinity, AFM, and DFT provides new insights into the environmental behavior of GO and the applications of GO in pollutant removal under exposure from HA.

Nanocolloids in Natural Water: Isolation, Characterization, and Toxicity.

Nanocolloids are widespread in natural water systems, but their characterization and ecological risks are largely unknown. Herein, tangential flow ultrafiltration (TFU) was used to separate and concentrate nanocolloids from surface waters. Unexpectedly, nanocolloids were present in high concentrations ranging from 3.7 to 7.2 mg/L in the surface waters of the Harihe River in Tianjin City, China. Most of the nanocolloids were 10-40 nm in size, contained various trace metals and polycyclic aromatic hydrocarbons, and exhibited fluorescence properties. Envelopment effects and aggregation of Chlorella vulgaris in the presence of nanocolloids were observed. Nanocolloids entered cells and nanocolloid-exposed cells exhibited stronger plasmolysis, chloroplast damage and more starch grains than the control cells. Moreover, nanocolloids inhibited the cell growth, promoted reactive oxygen species (ROS), reduce the chlorophyll a content and increased the cell permeability. The genotoxicity of nanocolloids was also observed. The metabolomics analysis revealed a significant ( p < 0.05) downregulation of amino acids and upregulation of fatty acids contributing to ROS increase, chlorophyll a decrease and plasmolysis. The present work reveals that nanocolloids, which are different from specific, engineered nanoparticles (e.g., Ag nanoparticles), are present at high concentrations, exhibit an obvious toxicity in environments, and deserve more attention in the future.

Effects of Graphene Oxide and Oxidized Carbon Nanotubes on the Cellular Division, Microstructure, Uptake, Oxidative Stress, and Metabolic Profiles.

Nanomaterial oxides are common formations of nanomaterials in the natural environment. Herein, the nanotoxicology of typical graphene oxide (GO) and carboxyl single-walled carbon nanotubes (C-SWCNT) was compared. The results showed that cell division of Chlorella vulgaris was promoted at 24 h and then inhibited at 96 h after nanomaterial exposure. At 96 h, GO and C-SWCNT inhibited the rates of cell division by 0.08-15% and 0.8-28.3%, respectively. Both GO and C-SWCNT covered the cell surface, but the uptake percentage of C-SWCNT was 2-fold higher than that of GO. C-SWCNT induced stronger plasmolysis and mitochondrial membrane potential loss and decreased the cell viability to a greater extent than GO. Moreover, C-SWCNT-exposed cells exhibited more starch grains and lysosome formation and higher reactive oxygen species (ROS) levels than GO-exposed cells. Metabolomics analysis revealed significant differences in the metabolic profiles among the control, C-SWCNT and GO groups. The metabolisms of alkanes, lysine, octadecadienoic acid and valine was associated with ROS and could be considered as new biomarkers of ROS. The nanotoxicological mechanisms involved the inhibition of fatty acid, amino acid and small molecule acid metabolisms. These findings provide new insights into the effects of GO and C-SWCNT on cellular responses.