Toxicity mitigation and biodistribution of albumin corona coated graphene oxide and carbon nanotubes in Caenorhabditis elegans.

In this work, the toxicity and biodistribution of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (MWCNT) were investigated in Caenorhabditis elegans. Bovine serum albumin (BSA) was selected as a model protein to evaluate the influence of protein corona formation on materials physicochemical properties, colloidal stability, and toxicity. Biological assays were performed to assess the effects of bare and albumin corona coated materials on survival, oxidative stress, intestinal barrier permeability, growth, reproduction, and fertility. Critical alterations in topography, surface roughness and chemistry of GO and MWCNT were observed due to albumin corona formation. These modifications were associated with changes in colloidal stability of materials and prevention of their aggregation and sedimentation in nematode testing medium. Both GO and MWCNT caused damage to nematode survival, growth, reproduction, and fertility, as well as enhanced oxidative stress and permeability of the intestinal barrier. But GO was more toxic than MWCNT to C. elegans, especially at long-term assays. Albumin corona mitigated 100% of acute and chronic effects of MWCNT. In contrast, the negative effects of GO were not completely mitigated; GO inhibited 16.2% of nematode growth, 86.5% of reproduction, and 32.0% of fertility at the highest concentration evaluated (10 mg L-1), while corona coated GO mitigated 50% and 100% of fertility and growth, respectively. Confocal Raman spectroscopy imaging was crucial to point out that bare and albumin corona coated GO and MWCNT crossed the C. elegans intestinal barrier reaching its reproductive organs. However, BSA corona protected the nematodes targeted organs from negative effects from MWCNT and blocked its translocation to other tissues, while coated GO was translocated inside the nematode affecting the functionality of crucial organs. In addition, coated MWCNT was excreted after 2 h of food resumption, whereas coated GO still accumulated in the nematode intestine. Our results demonstrate that the materials different translocation and excretion patterns in C. elegans had a relation to the impaired physiological functions of primary and secondary organs. This work is a contribution towards a better understanding of the impacts of protein corona on the toxicity of graphene oxide and carbon nanotubes; essential information for biological applications and nanosafety.

Mitigation of graphene oxide toxicity in C. elegans after chemical degradation with sodium hypochlorite.

Graphene oxide (GO) is a promising and strategic carbon-based nanomaterial for innovative and disruptive technologies. It is therefore essential to address its environmental health and safety aspects. In this work, we evaluated the chemical degradation of graphene oxide by sodium hypochlorite (NaClO, bleach water) and its consequences over toxicity, on the nematode Caenorhabditis elegans. The morphological, chemical, and structural properties of GO and its degraded product, termed NaClO-GO, were characterized, exploring an integrated approach. After the chemical degradation of GO at room temperature, its flake size was reduced from 156 to 29 nm, while NaClO-GO showed changes in UV-vis absorption, and an increase in the amount of oxygenated surface groups, which dramatically improved its colloidal stability in moderately hard reconstituted water (EPA medium). Acute and chronic exposure endpoints (survival, growth, fertility, and reproduction) were monitored to evaluate material toxicities. NaClO-GO presented lower toxicity at all endpoints. For example, an increase of over 100% in nematode survival was verified for the degraded material when compared to GO at 10 mg L-1. Additionally, enhanced dark-field hyperspectral microscopy confirmed the oral uptake of both materials by C. elegans. Finally, this work represents a new contribution toward a better understanding of the links between the transformation of graphene-based materials and nanotoxicity effects (mitigation), which is mandatory for the safety improvements that are required to maximize nanotechnological benefits to society.

Metabolic effects in the freshwater fish Geophagus iporangensis in response to single and combined exposure to graphene oxide and trace elements.

Graphene oxide (GO) is part of a new set of nanomaterials with particular characteristics related to its nanoscale size. Due to this feature, it presents high reactivity and other contaminants present in the environment could bind to them and affect its intrinsic toxicity. The metabolic effects of such nanomaterials and their combination with two common pollutants, zinc and cadmium, on the freshwater fish Geophagus iporangensis are analyzed. Moreover, metabolic rate and ammonia excretion were used as bioindicators to measure metabolic changes. Fishes were exposed for 24 h in filtered tap water to different concentrations of GO (0.5; 1.0; 2.0 and 4.0 mg L-1), Zn (0.5; 1.0; 2.0; 4.0 and 10.0 mg L-1) and Cd (0.1; 0.5; 1.0; 2.0 and 4.0 mg L-1). Combined effects were verified using the same concentrations of trace elements added to 1.0 mg L-1 of GO. Exposure to GO and Cd resulted in a decrease of metabolic rate in G. iporangensis, by about 30% compared to control means, in the highest concentration tested (4.0 mg L-1). However, zinc exposure in the highest concentration (10 mg L-1) raised metabolic rate to around three times that of the control group. Ammonia excretion was not affected by exposure to GO and Cd. In contrast, exposure to Zn at 10 mg L-1 raised the rate to around 47%. The combined exposure of GO and Zn intensified the effects of the trace element, inducing responses in both biomarkers at lower concentrations and demonstrating that the interaction between elements increases zinc's effects. The combination Cd + GO only affects metabolic rate. Thus, this metabolic rate alone reveals that combined exposure potentiates effects of trace elements on fish metabolism.

Co-exposure of graphene oxide with trace elements: Effects on acute ecotoxicity and routine metabolism in Palaemon pandaliformis (shrimp).

Graphene oxide (GO) has been evaluated for application in environmental remediation and pollution control strategies. However, the side effects caused by the interactions of GO with classical pollutants in aquatic environments are still largely unknown. In this work, the ecotoxicological effects of GO, cadmium, zinc and the interactions between GO and these trace elements (co-exposure) were evaluated through acute toxicity tests and routine metabolism (i.e., oxygen consumption and ammonia excretion) in Palaemon pandaliformis (shrimp). After 96 h of exposure, GO did not present acute ecotoxicity at concentrations up to 5.0 mg L-1. However, the association of GO with Cd or Zn increased the toxicity of these trace elements as demonstrated by the decrease in LC50 values. The 96 h LC50 of Cd associated with GO was 1.7 times less than the 96 h LC50 of Cd alone. Similarly, the 96 h LC50 of Zn associated with GO was 1.8 times less than the 96 h LC50 of Zn alone. Additionally, the co-exposure of GO with trace elements impaired the routine metabolism of P. pandaliformis. Finally, the GO potentiated the ecotoxicological effects of Cd and Zn in the shrimp model. Future research on this emerging nanomaterial should focus on its use and disposal in aquatic ecosystems.

Coating carbon nanotubes with humic acid using an eco-friendly mechanochemical method: Application for Cu(II) ions removal from water and aquatic ecotoxicity.

In this work, industrial grade multi-walled carbon nanotubes (MWCNT) were coated with humic acid (HA) for the first time by means of a milling process, which can be considered an eco-friendly mechanochemical method to prepare materials and composites. The HA-MWCNT hybrid material was characterized by atomic force microscopy (AFM), scanning electron microscopies (SEM and STEM), X-ray photoelectron spectroscopy (XPS), termogravimetric analysis (TGA), and Raman spectroscopy. STEM and AFM images demonstrated that the MWCNTs were efficiently coated by the humic acid, thus leading to an increase of 20% in the oxygen content at the nanotube surface as observed by the XPS data. After the milling process, the carbon nanotubes were shortened as unveiled by SEM images and the values of ID/IG intensity ratio increased due to shortening of the nanotubes and increasing in the number defects at the graphitic structure of carbon nanotubes walls. The analysis of TGA data showed that the quantity of the organic matter of HA on the nanotube surface was 25%. The HA coating was responsible to favor the dispersion of MWCNTs in ultrapure water (i.e. -42mV, zeta-potential value) and to improve their capacity for copper removal. HA-MWCNTs hybrid material adsorbed 2.5 times more Cu(II) ions than oxidized MWCNTs with HNO3, thus evidencing that it is a very efficient adsorbent material for removing copper ions from reconstituted water. The HA-MWCNTs hybrid material did not show acute ecotoxicity to the tested aquatic model organisms (Hydra attenuata, Daphnia magna, and Danio rerio embryos) up to the highest concentration evaluated (10mgL-1). The results allowed concluding that the mechanochemical method is effective to coat carbon nanotubes with humic acid, thus generating a functional hybrid material with low aquatic toxicity and great potential to be applied in environmental nanotechnologies such as the removal of heavy metal ions from water.

Record of Nile tilapia in the Mandira river, Cananéia, São Paulo state / Registro da tilápia-do-nilo no rio Mandira, Cananéia, estado de São Paulo

The present short communication reports the occurrence of Nile Tilapia (Oreochromis niloticus) in the Mandira River, in the extractive reserve in the Cananéia estuary, São Paulo State. In May 2014, using dip nets, we collected five specimens of O. niloticus in the estuary, with length ranging from 1.4 to 2.5 cm and weight between 0.8 and 2.3 g. Samplings performed in July indicated the presence of additional four specimens of O. niloticus in other stretches of the same river. The occurrence of alien species in conservation areas has high ecological importance, as they can cause environmental and biodiversity alterations; in Brazil, the introduction of alien species is usually related to economic activities, such as the Nile tilapia aquaculture.

A presente nota registra a ocorrência de tilápia-do-nilo (Oreochromis niloticus) na Reserva Extrativista do Rio Mandira, localizada no munícipio de Cananéia, São Paulo. Em maio de 2014, foram coletados por meio de puçás, cinco exemplares de O. niloticus no estuário, com comprimentos variando entre 1,5 a 2,5 cm e peso entre 0,8 e 2,3 g. Coletas realizadas em julho evidenciaram a presença de mais quatro espécimes de O. niloticus em outros trechos do rio estudado. A ocorrência de espécies exóticas em unidades de conservação é de extrema relevância ecológica, uma vez que pode modificar o ambiente e a biodiversidade de uma região, sendo que no Brasil, a introdução de espécies exóticas encontra-se tipicamente vinculada às atividades de interesse socioeconômico, como é o caso do cultivo de tilápia-do-nilo.

Record of Nile tilapia in the Mandira river, Cananéia, São Paulo state / Registro da tilápia-do-nilo no rio Mandira, Cananéia, estado de São Paulo

The present short communication reports the occurrence of Nile Tilapia (Oreochromis niloticus) in the Mandira River, in the extractive reserve in the Cananéia estuary, São Paulo State. In May 2014, using dip nets, we collected five specimens of O. niloticus in the estuary, with length ranging from 1.4 to 2.5 cm and weight between 0.8 and 2.3 g. Samplings performed in July indicated the presence of additional four specimens of O. niloticus in other stretches of the same river. The occurrence of alien species in conservation areas has high ecological importance, as they can cause environmental and biodiversity alterations; in Brazil, the introduction of alien species is usually related to economic activities, such as the Nile tilapia aquaculture.(AU)

A presente nota registra a ocorrência de tilápia-do-nilo (Oreochromis niloticus) na Reserva Extrativista do Rio Mandira, localizada no munícipio de Cananéia, São Paulo. Em maio de 2014, foram coletados por meio de puçás, cinco exemplares de O. niloticus no estuário, com comprimentos variando entre 1,5 a 2,5 cm e peso entre 0,8 e 2,3 g. Coletas realizadas em julho evidenciaram a presença de mais quatro espécimes de O. niloticus em outros trechos do rio estudado. A ocorrência de espécies exóticas em unidades de conservação é de extrema relevância ecológica, uma vez que pode modificar o ambiente e a biodiversidade de uma região, sendo que no Brasil, a introdução de espécies exóticas encontra-se tipicamente vinculada às atividades de interesse socioeconômico, como é o caso do cultivo de tilápia-do-nilo.(AU)

The exotic species Litopenaeus vannamei (Boone, 1931) occurrence in Cananeia, Iguape and Ilha Comprida Lagoon Estuary Complex / A ocorrência da espécie exótica Litopenaeus vannamei (Boone, 1931) no complexo Estuarino-Lagunar de Cananéia, Iguape e Ilha Comprida

Exotic species are an exponential problem throughout the world, being one of the main causes of alterations both of the environment and of biodiversity. The introduction of exotic species is typically linked to activities of socioeconomic relevance. The consequences of such invasions have ecological, economic and sanitary components, and these components sometimes operate synergistically. The present study records the presence of Litopenaeus vannamei in several areas of Cananéia, Iguape and Ilha Comprida estuary. A total of 109 samples taken with a gerival net were examined to evaluate the presence of L. vannamei as a bycatch of fishing activities seeking Farfantepenaeus paulensis, F. brasiliensis and Litopenaeus schmitti, between March 2005 and December 2013. Sixty-four individuals of L. vannamei were captured the size and weight of the smallest and the largest specimens of which were, respectively: 1.68 and 6.30 cm and 26.70 and 31.78 g. The data give no indication that L. vannamei is proliferating in the region to the point of being considered an invasive species nor that it is causing economic problems.

As espécies exóticas constituem hoje em um problema exponencial de escala global e um dos principais fatores de modificações do meio ambiente e da biodiversidade de uma região. A introdução de espécies exóticas encontra-se tipicamente vinculada às atividades de interesse sócio-econômico. As invasões têm consequências ecológicas, econômicas e sanitárias, atuando, às vezes, de modo sinergético. O presente trabalho registra a ocorrência de Litopenaeus vannamei em várias áreas do estuário de Cananeia, Iguape e Ilha Comprida. Para avaliar a ocorrência do L. vannamei junto à pesca de Farfantepenaeus paulensis, F. brasiliensis e Litopenaeus schmitti foram realizadas 109 amostragens com rede gerival, de março de 2005 a dezembro de 2013. Foram capturados 64 exemplares de L. vannamei com tamanhos e pesos médios da menor para maior espécime capturada de 1,68 para 6,30 cm e 26,70 para 31,78 g, respectivamente. Os dados não indicam que L. vannamei está proliferando na região, a ponto de ser considerado uma espécie invasora e causando problemas econômicos.

The exotic species Litopenaeus vannamei (Boone, 1931) occurrence in Cananeia, Iguape and Ilha Comprida Lagoon Estuary Complex / A ocorrência da espécie exótica Litopenaeus vannamei (Boone, 1931) no complexo Estuarino-Lagunar de Cananéia, Iguape e Ilha Comprida

Exotic species are an exponential problem throughout the world, being one of the main causes of alterations both of the environment and of biodiversity. The introduction of exotic species is typically linked to activities of socioeconomic relevance. The consequences of such invasions have ecological, economic and sanitary components, and these components sometimes operate synergistically. The present study records the presence of Litopenaeus vannamei in several areas of Cananéia, Iguape and Ilha Comprida estuary. A total of 109 samples taken with a gerival net were examined to evaluate the presence of L. vannamei as a bycatch of fishing activities seeking Farfantepenaeus paulensis, F. brasiliensis and Litopenaeus schmitti, between March 2005 and December 2013. Sixty-four individuals of L. vannamei were captured the size and weight of the smallest and the largest specimens of which were, respectively: 1.68 and 6.30 cm and 26.70 and 31.78 g. The data give no indication that L. vannamei is proliferating in the region to the point of being considered an invasive species nor that it is causing economic problems.(AU)

As espécies exóticas constituem hoje em um problema exponencial de escala global e um dos principais fatores de modificações do meio ambiente e da biodiversidade de uma região. A introdução de espécies exóticas encontra-se tipicamente vinculada às atividades de interesse sócio-econômico. As invasões têm consequências ecológicas, econômicas e sanitárias, atuando, às vezes, de modo sinergético. O presente trabalho registra a ocorrência de Litopenaeus vannamei em várias áreas do estuário de Cananeia, Iguape e Ilha Comprida. Para avaliar a ocorrência do L. vannamei junto à pesca de Farfantepenaeus paulensis, F. brasiliensis e Litopenaeus schmitti foram realizadas 109 amostragens com rede gerival, de março de 2005 a dezembro de 2013. Foram capturados 64 exemplares de L. vannamei com tamanhos e pesos médios da menor para maior espécime capturada de 1,68 para 6,30 cm e 26,70 para 31,78 g, respectivamente. Os dados não indicam que L. vannamei está proliferando na região, a ponto de ser considerado uma espécie invasora e causando problemas econômicos.(AU)