In recent decades, nanotechnology has rapidly developed. Therefore, there is growing concern about the potential environmental risks of nanoparticles (NPs). Caenorhabditis elegans (C. elegans) has been used as a powerful tool for studying the potential ecotoxicological impacts of nanomaterials from the whole animal level to single cell level, especially in the area of reproduction. In this review, we discuss the reproductive toxicity of common nanomaterials in C. elegans, such as metal-based nanomaterial (silver nanoparticles (NPs), gold NPs, zinc oxide NPs, copper oxide NPs), carbon-based nanomaterial (graphene oxide, multi-walled carbon nanotubes, fullerene nanoparticles), polymeric NPs, silica NPs, quantum dots, and the potential mechanisms involved. This insights into the toxic effects of existing nanomaterials on the human reproductive system. In addition, we summarize how the physicochemical properties (e.g., size, charge, surface modification, shape) of nanomaterials influence their reproductive toxicity. Overall, using C. elegans as a platform to develop rapid detection techniques and prediction methods for nanomaterial reproductive toxicity is expected to reduce the gap between biosafety evaluation of nanomaterials and their application.

Diclofop-methyl (DM) is one of the most widely used herbicides in agriculture production and has been frequently detected in both freshwater and environments, even agricultural products. However, the potential toxic effects of DM on organisms and the underlying mechanisms are still poorly understood. In this study, we utilized zebrafish to evaluate the toxicity of DM during the cardiovascular developmental process. Exposure of zebrafish embryos to 0.75, 1.0 and 1.25 mg/L DM induced cardiac defects, such as pericardial edema, slow heart rate and long SV-BA distance but the vascular development in zebrafish larvae was not influenced by DM treatment. The expression of cardiac-related genes were disordered and DM exposure initiated disordering cardiogenesis from the period of precardiac mesoderm formation. Moreover, the apoptosis and proliferation of cardiomyocytes were not influenced but the levels of oxidative stress were upregulated by DM exposure. Fullerenes and astaxanthin was able to rescue cardiac defects caused by DM via downregulating oxidative stress. Wnt signaling was downregulated after DM treatment and activation of Wnt signaling could rescue cardiac defects. Therefore, our results suggest that DM has the potential to induce cardiac developmental toxicity through upregulation of Wnt-Mediated (reactive oxygen species) ROS generation in zebrafish larvae.

Environmental mobility of C60 fullerene can be significantly affected in the presence of naturally abundant α-FeOOH. However, α-FeOOH vary significantly in sizes, shapes and associated properties that can greatly influence the fate and transport of C60 fullerene in environmental media. Therefore, colloidal hetero-association between well crystallized low aspect (LAsp) α-FeOOH and nC60 fullerene may differ substantially to weakly crystallized high-aspect (HAsp) counterpart. In contrast to LAsp α-FeOOH, inherent crystal defects and surface charge generation in HAsp α-FeOOH facilitated strong Coulombic attraction and aggregation with fullerene in acidic pH. However, LAsp α-FeOOH demonstrated subtle entropic depletion mediated interaction with fullerene prevalent in hard rods. Humic acid (HA) encapsulation of HAsp α-FeOOH substantially blocked fullerene attachment. Minute enhancement in colloidal stability was detected for HA-coated HAsp α-FeOOH and fullerene mixture to HA-coated HAsp α-FeOOH alone. To investigate the interfacial assembly of α-FeOOH with fullerene “in situ” differential interference contrast (DIC) microscopic investigations were employed. This study showed significantly different interface behavior of the binary mixtures of fullerene and HAsp α-FeOOH NPs, and LAsp particles. On air-water interface, bare HAsp α-FeOOH displayed liquid crystalline packing. However, addition of fullerene to HAsp α-FeOOH suspension at pH5 produced closed-loop polygonal and circular ring structures. Head-to-tail alignment of magnetic dipoles as well as fullerene hydrophobicity facilitated such assembly formation. “Ex situ” AFM investigation revealed further the presence of magnetically derived ring structure which asserts that the formed “in situ” ensembles were not transient, hence, may abate fullerene transport through environmental interfaces. Barring hydrophobicity assisted attachment of fullerene to LAsp α-FeOOHs, the absence of any close-packed structures may unlikely abate fullerene transport as envisaged in case of HAsp α-FeOOH. Thus, aspect ratio variation and associated material properties of naturally abundant α-FeOOH may significantly impact fullerene transport through environmental media.

Recent studies indicate that while unfunctionalized carbon nanomaterials (CNMs) exhibit very low decomposition rates in soils, even minor surface functionalization (e.g., as a result of photochemical weathering) may accelerate microbial decay. We present results from a C60 fullerene-soil incubation study designed to investigate the potential links between photochemical and microbial degradation of photo-irradiated C60. Irradiating aqueous ¹³C-labeled C60 with solar-wavelength light resulted in a complex mixture of intermediate products with decreased aromaticity. Although addition of irradiated C60 to soil microcosms had little effect on net soil respiration, excess ¹³C in the respired CO2 demonstrates that photo-irradiating C60 enhanced its degradation in soil, with ∼0.78% of 60 day photo-irradiated C60 mineralized. Community analysis by DGGE found that soil microbial community structure was altered and depended on the photo-treatment duration. These findings demonstrate how abiotic and biotic transformation processes can couple to influence degradation of CNMs in the natural environment.

We tested the resistance of five different fullerenes (C₆₀, C₇₀, C₇₆/₇₈ mix, and C₈₄) to chemothermal oxidation at 375 °C (CTO-375), a method that has been used and tested for quantifying black carbon (BC) and CNTs in soils and sediments. C₆₀ survived CTO-375 the most (50%), while C₇₀ was the fullerene with the lowest survival rate (<1%). Standard additions of C₆₀ to soil and sediment reference materials yielded recoveries between 18 and 36%. Although lower than recoveries previously observed for soot and CNTs, these results demonstrate the capability of CTO-375 to partially isolate C₆₀ from solid environmental matrices. Standard additions of C₇₀, C₇₆/₇₈, and C₈₄ yielded slightly higher survival rates when added to soil and sediment than in their pure form. These results indicate that the mineral matrices of these samples probably had a catalytic effect towards C₆₀ and a protective effect towards C₇₀, C₇₆/₇₈, and C₈₄ during CTO-375.

This study evaluated hormetic effect of oxidative stress exerted by fullerene crystals (nC₆₀) on Daphnia pulex, employing transcriptomics and metabolomics. D. pulex were exposed to various concentrations of nC₆₀ for 21 days. Hormetic effect of oxidative stress was most evident after 7 days, with markedly increased L-Glutathione (GSH) concentration and Superoxide Dismutase (SOD) activity at low doses of nC₆₀ exposure, and oppositely at high doses. The transcriptomics and metabolomics were used to elucidate the molecular mechanism underlying the hormesis in oxidative stress. There were significant alterations in major pathways involving oxidative stress and energy metabolism in D. pulex. Some important intermediates and the expression of their regulatory genes coincided with each other with first up-regulated and then down-regulated with the concentration increased, consistent with the hormesis description. The nC₆₀ interfered the TCA cycle of D. pulex. The synthesis of L-cysteine and glutamate was directly affected, and further disturbed the synthesis of GSH. This work is of great significance to provide the molecular-level evidence into the hormetic effect in oxidative stress of D. pulex exposed to nC₆₀.

The mutual influences of C₆₀ fullerene (C₆₀) and heavy metal ions (Cd, Cu, and Pb) on the uptake, transportation, and accumulation of these coexisting pollutants in four rice cultivars planted in agricultural soil were investigated during the whole life cycle of rice. The biomass of the rice plants was not affected significantly by the presence of C₆₀. C₆₀ exposure exerted different impacts on the bioaccumulation of Cd, Cu, and Pb in various rice tissues. For example, the bioaccumulation of Cd in rice 9311 panicles was significantly decreased (p < .05) when it was exposed to 1000 mg/kg C₆₀, whereas the changes of Cu and Pb levels in panicles were not statistically significant. C₆₀ was absorbed by rice roots and transported to the stems and panicles, and it tended to form aggregates in rice tissues. C₆₀ concentrations in the roots, stems, and panicles of the four rice cultivars that were harvested after a 130-day exposure to 600 mg/kg C₆₀ were 40–292, 4.4–24.5 and 0.077–1.2 mg/kg (dry weight), respectively. C₆₀ and heavy metal ions exhibited different uptake and transportation mechanisms, which depended on the rice cultivar, soil heavy metal ion concentration, and C₆₀ exposure time and concentration. For example, the average C₆₀ in the four rice cultivars was increased sharply, from 47.4 to 196.3 mg/kg from the tillering to booting stages, whereas Cd levels increased only slightly, from 23.1 to 25.9 mg/kg. The study demonstrated that the bioaccumulation of C₆₀ and heavy metal ions under co-contamination scenario differs from under single contaminant. The accumulation of C₆₀ in rice panicles may increase the concern of food safety.

The life cycle parameters of the benthic invertebrate Chironomus riparius make it a relevant organism for use in multi-generation chronic ecotoxicology tests. Since studies on chronic exposures with fullerene carbon nanoparticles have revealed adverse effects at lower concentration ranges, it is crucial to gain understanding of the consequences in following generations. The aims of this study were to investigate whether sediment-associated fullereneC60 impacts on C. riparius emergence and breeding, thus affecting the growth of the second generation. Larvae were exposed to fullerene-spiked sediment at concentrations of 0.5, 10 and 40 mg/kg sediment dw. Total emergence and breeding success were monitored after the first generation and the newly hatched larvae from the first generation exposure were transferred either to continuous exposure or to pristine sediments without fullerene. Findings indicate that the presence of fullerenes have major impacts on the first generation, mainly shown as delayed emergence time of females. Increased larval growth was observed in the second generation, and we conclude that the C. riparius response to fullerene exposure indicated significant signs of recovery in second-generation larval growth. The result shows the effects to be important for population dynamics, revealing delayed female emergence time, which leads to situation where adults’ breeding is inhibited.

Fullerenes are carbon based nanoparticles that may enter the environment as a consequence of both natural processes and human activities. Although little is known about the presence of these chemicals in the environment, recent studies suggested that soil may act as a sink. The aim of the present work was to investigate the presence of fullerenes in soils collected in The Netherlands. Samples (n = 91) were taken from 6 locations and analyzed using a new developed LC-QTOF-MS method. The locations included highly trafficked and industrialized as well as urban and natural areas. In general, C60 was the most abundant fullerene found in the environment, detected in almost a half of the samples and at concentrations in the range of ng/kg. Other fullerenes such as C70 and an unknown structure containing a C60 cage were detected to a lower extent. The highest concentrations were found in the proximity of combustion sites such as a coal power plant and an incinerator, suggesting that the nanoparticles were unintentionally produced during combustions processes and reached the soil through atmospheric deposition. Consistent with other recent studies, these results show that fullerenes are widely present in the environment and that the main route for their entrance may be due to human activities. These data will be helpful in the understanding of the distribution of fullerenes in the environment and for the study of their behavior and fate in soil.

Airborne particles containing elemental carbon (EC) are currently at the forefront of scientific and regulatory scrutiny, including black carbon, carbon black, and engineered carbon-based nanomaterials, e.g., carbon nanotubes, fullerenes, and graphene. Scientists and regulators sometimes group these EC-containing particles together, for example, interchangeably using the terms carbon black and black carbon despite one being a manufactured product with well-controlled properties and the other being an undesired, incomplete-combustion byproduct with diverse properties. In this critical review, we synthesize information on the contrasting properties of EC-containing particles in order to highlight significant differences that can affect hazard potential. We demonstrate why carbon black should not be considered a model particle representative of either combustion soots or engineered carbon-based nanomaterials. Overall, scientific studies need to distinguish these highly different EC-containing particles with care and precision so as to forestall unwarranted extrapolation of properties, hazard potential, and study conclusions from one material to another.