Nanomaterials in the Environment: Perspectives on in Vivo Terrestrial Toxicity Testing

Mendonça, Monique Culturato Padilha; Rizoli, Cintia; Ávila, Daiana Silva; Amorim, Mónica J.B.; Jesus, Marcelo Bispo de

doi:10.3389/fenvs.2017.00071

Cited by 11 publications

(15 citation statements)

References 46 publications

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“…With the use of CNTs becoming more widespread, the amount of CNTs released into the environment is expected to increase, either accidentally or as waste, raising concerns about their impact on human health and ecosystems. Recent studies have reported that some CNTs exhibit toxicity to plants, animals, and microorganisms (Chen et al, 2015b;Kumarathasan et al, 2015;Hatami, 2017;Mendonca et al, 2017;Chen et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Contribution of the Fenton reaction to the degradation of carbon nanotubes by enzymes

Takahashi

Taguchi

Hori

2023

Front. Environ. Sci.

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The widespread use of carbon nanotubes (CNTs) has raised concerns about the human health and ecological effects of CNTs released into the environment. Bacteria play an important role in bioremediation and waste treatment, and their enzymes are mostly responsible for the degradation of contaminants. However, there are still only a few reports about the bacterial degradation of CNTs, and evidence showing the involvement of bacterial enzymes in CNT degradation with their mechanisms has never been reported. The purpose of this study is to clarify whether CNTs can be degraded by bacterial enzymes. In this study, the degradation of oxidized (carboxylated) single-walled CNTs (O-SWCNTs) by mt2DyP, a dye-decolorizing peroxidase of Pseudomonas putida mt-2, a common soil bacterium, was investigated. After incubation of O-SWCNTs with recombinant mt2DyP and its substrate H2O2 for 30 d, the optical absorbance and Raman spectra revealed the degradation of O-SWCNTs. However, inactivation of the enzyme was observed within 60 min of the start of incubation, suggesting that the degradation of O-SWCNTs occurred nonenzymatically. The inactivation of mt2DyP was accompanied by the release of iron, the active center metal, and degradation of O-SWCNTs was significantly inhibited in the presence of diethylenetriamine pentaacetic acid, a chelating agent, indicating that O-SWCNTs were degraded by the Fenton reaction with iron released from mt2DyP and H2O2. The same phenomenon was observed with P450, which is also a heme enzyme. Furthermore, we investigated the contribution of the Fenton reaction to the O-SWCNT degradation by horseradish peroxidase (HRP), which was reported to enzymatically and rapidly degrade O-SWCNTs. Our results revealed that the degradation of O-SWCNTs in the presence of HRP is also mainly due to the Fenton reaction, with negligible enzymatic degradation. This contradicts the report showing enzymatic degradation of O-SWCNTs by HRP but supports the subsequent report quantitatively showing very slow transformation of O-SWCNTs by HRP. The current results emphasize that the Fenton reaction, which has received little attention in CNT degradation by heme enzymes, must be taken into consideration and will contribute to the development of a simple disposal method for CNTs, utilizing the Fenton reaction with bacteria/bacterial enzymes and H2O2.

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Section: Introductionmentioning

confidence: 99%

Contribution of the Fenton reaction to the degradation of carbon nanotubes by enzymes

Takahashi

Taguchi

Hori

2023

Front. Environ. Sci.

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“…In C. elegans, it was found that proteins involved in oxidative stress protection and metal elimination, such as SOD isoforms, metallothioneins and heat shock proteins, have a key role in resistance to TiO 2 NPs. These NPs led to a substantial decrease in both head thrash or body bend in nematode mutants (SOD-2, SOD-3, metallothionein-2 and heat shock protein-16.48) compared to the wild type [136].…”

Section: Titanium Nanomaterialsmentioning

confidence: 96%

“…Cadmium telluride quantum dots (CdTe QDs) caused abnormal foraging behavior (related to the altered function of the motor neurons) in C. elegans, at long-term early onset exposure. Thus, a decrease in fluorescence of the motor neurons cell bodies was observed, indicating an alteration in their development [136]. The main route of exposure of nematodes to QDs was determined, by fluorescence microscopy, to be through the digestive tracts [150].…”

Section: Cadmium Nanomaterialsmentioning

confidence: 99%

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Evaluation of Ecotoxicology Assessment Methods of Nanomaterials and Their Effects

Boros

Ostafe

2020

Nanomaterials

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This paper describes the ecotoxicological effects of nanomaterials (NMs) as well as their testing methods. Standard ecotoxicity testing methods are applicable to nanomaterials as well but require some adaptation. We have taken into account methods that meet several conditions. They must be properly researched by a minimum of ten scientific articles where adaptation of the method to the NMs is also presented; use organisms suitable for simple and rapid ecotoxicity testing (SSRET); have a test period shorter than 30 days; require no special equipment; have low costs and have the possibility of optimization for high-throughput screening. From the standard assays described in guidelines developed by organizations such as Organization for Economic Cooperation and Development and United States Environmental Protection Agency, which meet the required conditions, we selected as methods adaptable for NMs, some methods based on algae, duckweed, amphipods, daphnids, chironomids, terrestrial plants, nematodes and earthworms. By analyzing the effects of NMs on a wide range of organisms, it has been observed that these effects can be of several categories, such as behavioral, morphological, cellular, molecular or genetic effects. By comparing the EC50 values of some NMs it has been observed that such values are available mainly for aquatic ecotoxicity, with the most sensitive test being the algae assay. The most toxic NMs overall were the silver NMs.

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“…Some CNTs are needle-like, similar to asbestos, and can induce mesothelioma, pleural fibrosis, and lung cancer ( Donaldson et al, 2013 ). Recent studies have reported that some CNTs are also toxic to plants, animals, and microorganisms, and may alter biodiversity ( Chen et al, 2017 ; Mendonca et al, 2017 ; Chen et al, 2018 ; Kong et al, 2023 ); Such CNTs cause growth inhibition and reduced seed germination in plants ( Begum and Fugetsu, 2012 ; Hatami, 2017 ), embryo growth inhibition and pneumonia in animals ( Roman et al, 2013 ; Al Moustafa et al, 2016 ; Fujita et al, 2016 ), and cell membrane damage in microorganisms ( Liu et al, 2009 ; Yadav et al, 2016 ). As the use of CNTs has become more widespread, the amount of CNTs released into the environment, either accidentally or as waste, may also increase, leading to additional concerns.…”

Section: Introductionmentioning

confidence: 99%

Long-term continuous degradation of carbon nanotubes by a bacteria-driven Fenton reaction

Takahashi,

Hori

2023

Front. Microbiol.

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Very few bacteria are known that can degrade carbon nanotubes (CNTs), and the only known degradation mechanism is a Fenton reaction driven by Labrys sp. WJW with siderophores, which only occurs under iron-deficient conditions. No useful information is available on the degradation rates or long-term stability and continuity of the degradation reaction although several months or more are needed for CNT degradation. In this study, we investigated long-term continuous degradation of oxidized (carboxylated) single-walled CNTs (O-SWCNTs) using bacteria of the genus Shewanella. These bacteria are widely present in the environment and can drive the Fenton reaction by alternating anaerobic-aerobic growth conditions under more general environmental conditions. We first examined the effect of O-SWCNTs on the growth of S. oneidensis MR-1, and it was revealed that O-SWCNTs promote growth up to 30 μg/mL but inhibit growth at 40 μg/mL and above. Then, S. oneidensis MR-1 was subjected to incubation cycles consisting of 21-h anaerobic and 3-h aerobic periods in the presence of 30 μg/mL O-SWCNTs and 10 mM Fe(III) citrate. We determined key factors that help prolong the bacteria-driven Fenton reaction and finally achieved long-term continuous degradation of O-SWCNTs over 90 d. By maintaining a near neutral pH and replenishing Fe(III) citrate at 60 d, a degraded fraction of 56.3% was reached. S. oneidensis MR-1 produces Fe(II) from Fe(III) citrate, a final electron acceptor for anaerobic respiration during the anaerobic period. Then, ·OH is generated through the Fenton reaction by Fe(II) and H2O2 produced by MR-1 during the aerobic period. ·OH was responsible for O-SWCNT degradation, which was inhibited by scavengers of H2O2 and ·OH. Raman spectroscopy and X-ray photoelectron spectroscopy showed that the graphitic structure in O-SWCNTs was oxidized, and electron microscopy showed that long CNT fibers initially aggregated and became short and isolated during degradation. Since Shewanella spp. and iron are ubiquitous in the environment, this study suggests that a Fenton reaction driven by this genus is applicable to the degradation of CNTs under a wide range of conditions and will help researchers develop novel methods for waste treatment and environmental bioremediation against CNTs.

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Nanomaterials in the Environment: Perspectives on in Vivo Terrestrial Toxicity Testing

Cited by 11 publications

References 46 publications

Contribution of the Fenton reaction to the degradation of carbon nanotubes by enzymes

Contribution of the Fenton reaction to the degradation of carbon nanotubes by enzymes

Evaluation of Ecotoxicology Assessment Methods of Nanomaterials and Their Effects

Long-term continuous degradation of carbon nanotubes by a bacteria-driven Fenton reaction

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