Experimental datasets on the characterization of graphene oxide and its reproductive and developmental effects on Japanese medaka (Oryzias latipes) fish.

The datasets of this article present the experimental parameters resulting from the synthesis and characterization of graphene oxide (GO) using scanning and transmission electron microscopy (SEM, TEM) and spectrophotometric (FTIR, AFM, EDX) methods, and the assessment of its toxicological and endocrine-disrupting effects on the Japanese medaka fish by acute toxicity testing, and histopathological evaluations. These datasets support the article "Reproductive and Developmental Effects of Graphene Oxide on Japanese Medaka (Oryzias latipes)". GO synthesis was performed following the modified Hummer's method. Its particle diameter and zeta potential were determined using Zeta Sizer Nano ZS analyzer, and characterized by SEM and TEM. After 5 min sonication in water, GO (25-200 µg/g) was injected intraperitoneally to the reproductively active male and female fish maintained as a breeding pair (one male, one female) in 500 mL balanced salt solution (BSS) in glass jars under standard laboratory conditions (25±1 °C; 16L:8D light cycle). The control fish were injected with water. The maximum volume of the injected material is 1 µL/10 mg body weight. To avoid movement, during injection the fish were briefly anesthetized in MS 222 (100 mg/L) and after injection transferred to BSS for recovery. LD50 values of GO related to fish mortality were determined from the linear regression analysis using a software program. Reproductive activities (fecundity) were determined by daily collection of eggs 7 days before and 21 days after injection from a breeding pair and expressed as percent eggs laid every day post-injection relative to the average (mean of 7 days) eggs laid prior to injection. Developmental abnormalities of the embryos were assessed by culturing the collected fertilized eggs in ERM for a maximum period of 14 day-post fertilization (dpf). The fish that survived after 21days post-injection were sacrificed and the entire fish excluding post-anal tail were cut into three small pieces and fixed in 4% paraformaldehyde containing 0.05% Tween 20. Histopathological evaluations of gonads (ovary and testis), liver, and kidneys were made in 5 µm thick sections stained mainly on hematoxylin and eosin (HE) following the guidelines published by OECD. The Photomicrographs of the sections were made using Olympus B-max 40 microscope attached to a camera with Q-capture Pro 7 software or in Nikon Eclipse 50i microscope attached to Nikon DS-Fi1 camera. Four types of follicles in the stromal compartments of the ovary, perinucleolar (PNO), cortical alveolar (CAO), early vitellogenic (EVO) and late vitellogenic (LVO) were considered as differentiating, and the post ovulatory and atretic follicles were considered as degenerating follicles, and counted in an entire section made through four different regions (anterior, upper middle, lower middle, and anal) of the ovary. The follicular data were expressed as percent follicles (individual follicles or differentiating or degenerating) or as the ratio of differentiating and degenerating follicles found in that particular region of the ovary. The data were analyzed either by one- or two-way ANOVA followed by post-hoc Tukey's multiple comparison test and expressed as means ±SEM.

Assessment of reproductive and developmental effects of graphene oxide on Japanese medaka (Oryzias latipes).

Due to its unique properties, graphene oxide (GO) has potential for biomedical and electronic applications, however environmental contamination including aquatic ecosystem is inevitable. Moreover, potential risks of GO in aquatic life are inadequately explored. Present study was designed to evaluate GO as an endocrine disrupting chemical (EDC) using the model Japanese medaka (Oryzias latipes). GO was injected intraperitoneally (25-200 µg/g) once to breeding pairs and continued pair breeding an additional 21 days. Eggs laid were analyzed for fecundity and the fertilized eggs were evaluated for developmental abnormalities including hatching. Histopathological evaluation of gonads, liver, and kidneys was made 21 days post-injection. LD50 was found to be sex-dependent. Fecundity tended to reduce in a dose-dependent manner during early post-injection days; however, the overall evaluation showed no significant difference. The hatchability of embryos was reduced significantly in the 200 µg/g group; edema (yolk and cardiovascular) and embryo-mortality remained unaltered. Histopathological assessment identified black particles, probably agglomerated GO, in the gonads of GO-treated fish. However, folliculogenesis in stromal compartments of ovary and the composition of germinal elements in testis remained almost unaltered. Moreover, granulosa and Leydig cells morphology did not indicate any significant EDC-related effects. Although liver and kidney histopathology did not show GO as an EDC, some GO-treated fish accumulated proteinaceous fluid in hepatic vessels and induced hyperplasia in interstitial lymphoid cells (HIL) located in kidneys. GO agglomerated in medaka gonads after 21-days post-injection. However, gonad histopathology including granulosa and Leydig cells alterations were associated with GO toxicity rather than EDC effects.

Graphene-Based Nanomaterials Toxicity in Fish.

Due to their unique physicochemical properties, graphene-based nanoparticles (GPNs) constitute one of the most promising types of nanomaterials used in biomedical research. GPNs have been used as polymeric conduits for nerve regeneration and carriers for targeted drug delivery and in the treatment of cancer via photothermal therapy. Moreover, they have been used as tracers to study the distribution of bioactive compounds used in healthcare. Due to their extensive use, GPN released into the environment would probably pose a threat to living organisms and ultimately to human health. Their accumulation in the aquatic environment creates problems to aquatic habitats as well as to food chains. Until now the potential toxic effects of GPN are not properly understood. Despite agglomeration and long persistence in the environment, GPNs are able to cross the cellular barriers successfully, entered into the cells, and are able to interact with almost all the cellular sites including the plasma membrane, cytoplasmic organelles, and nucleus. Their interaction with DNA creates more potential threats to both the genome and epigenome. In this brief review, we focused on fish, mainly zebrafish (Danio rerio), as a potential target animal of GPN toxicity in the aquatic ecosystem.

Antimicrobial Activity of Gold Nanoparticles and Ionic Gold.

Gold, in both nanoparticle (AuNPs) and ionic forms, has been studied for antibiotic activities. Some of the organic complexes of Au (I & III) ions are antibacterial. AuNPs are antifungal, but with conflicting results on their antibacterial activity. We summarized these publications and found that AuNPs are generally not bactericidal, or only weakly at high concentrations. However, the reason AuNPs appear to be bactericidal is possibly due to the bactericidal activity of co-existing chemicals not completely removed from AuNPs: gold ions, surface coating agents, and chemicals involved in the synthesis. AuNPs can also act as carriers or delivery vehicles of antibiotics, thus enhancing the bactericidal effect of the antibiotics.

Determination of the mechanism of photoinduced toxicity of selected metal oxide nanoparticles (ZnO, CuO, Co3O4 and TiO2) to E. coli bacteria.

Cytotoxicity of selected metal oxide nanoparticles (MNPs) (ZnO, CuO, Co3O4 and TiO2) was investigated in Escherichia coli both under light and dark conditions. Cytotoxicity experiments were conducted with spread plate counting and the LC50 values were calculated. We determined the mechanism of toxicity via measurements of oxidative stress, reduced glutathione, lipid peroxidation, and metal ions. The overall ranking of the LC50 values was in the order of ZnO < CuO < Co3O4 < TiO2 under dark condition and ZnO < CuO < TiO2 < Co3O4 under light condition. ZnO MNPs were the most toxic among the tested nanoparticles. Our results indicate depletion of reduced glutathione level and elevation of malondialdehyde level correlated with the increase in oxidative stress. Released metal ions were found to have partial effect on the toxicity of MNPs to E. coli. In summary, the dynamic interactions of multiple mechanisms lead to the toxicity of the tested MNPs to E. coli.

Effect of humic acids and sunlight on the cytotoxicity of engineered zinc oxide and titanium dioxide nanoparticles to a river bacterial assemblage.

The effect of a terrestrial humic acid (HA) and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles (ZnONPs) and titanium dioxide nanoparticles (TiO2NPs) to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA (10 and 40 ppm) on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight (light irradiation (LI)). The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments: HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.

Using nano-QSAR to predict the cytotoxicity of metal oxide nanoparticles.

It is expected that the number and variety of engineered nanoparticles will increase rapidly over the next few years, and there is a need for new methods to quickly test the potential toxicity of these materials. Because experimental evaluation of the safety of chemicals is expensive and time-consuming, computational methods have been found to be efficient alternatives for predicting the potential toxicity and environmental impact of new nanomaterials before mass production. Here, we show that the quantitative structure-activity relationship (QSAR) method commonly used to predict the physicochemical properties of chemical compounds can be applied to predict the toxicity of various metal oxides. Based on experimental testing, we have developed a model to describe the cytotoxicity of 17 different types of metal oxide nanoparticles to bacteria Escherichia coli. The model reliably predicts the toxicity of all considered compounds, and the methodology is expected to provide guidance for the future design of safe nanomaterials.

The effect of humic acids on the cytotoxicity of silver nanoparticles to a natural aquatic bacterial assemblage.

The effect of a terrestrial humic acid (HA) and a river HA on the cytotoxicity of silver nanoparticles (AgNPs) to natural aquatic bacterial assemblages (0 µM, 2.5 µM and 5 µM) was measured with spread plate counting. The effect of HA (20 and 40 ppm) on the cytotoxicity of AgNPs ranging in size between 15 and 25 nm was tested in the presence and in the absence of natural sunlight. The experiment was a full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS. LSMEANS was used to separate the means or combinations of means. Significant main effects of all independent variables, plus interaction effects in all cases except HA/LI and HA/AgNPs/LI were observed. The toxicity of AgNPs to natural aquatic bacterial assemblages appears to be concentration dependent for concentrations between 0 µM and 5 µM. The data indicate that the light exposure inhibited viability more than the darkness exposure. The HA treatment groups in the presence of light showed greater reduced viability count compared to darkness exposure groups. The inhibition of bacterial viability counts by AgNPs exposure was less in the light treatment groups containing a terrestrial HA compared to that with a river HA. Difference in the extent of reactive oxygen species formation and adsorption/binding of AgNPs was speculated to account for the observed phenomenon.