77
and Ward 2018; Jia et al. 2019; OECD 2013; Piersma 2011) (Table 5.1). Recently,
the zebrafish embryonic test was also standardized for testing metallic nanomaterials
(Pecoraro et al. 2017) and to assess the biodistribution of polystyrene nanoparticles
(nanoplastics) in the developing embryo (Lee et al. 2019; van Pomeren et al. 2017a).
The test is versatile, performing well to assess the toxicity and the embryotoxicity
in pharmacology as in ecotoxicology, requires small quantities of nanomaterials, is
reproducible, predictive, highly standardized, and easy to perform also in automated
systems. Herein, we present a synthetic overview of the results.
Among the alternative methods for embryotoxicity, the zebrafish embryonic test
was the most used to test the carbon-based nanomaterials. The exposure to buckminsterfullerene, such as C60, C70, and C98, induced excess of mortality and heart
and caudal fin malformations at doses lower than 1.5 μg/ml. concentration inducing
50% lethality in the sample was very low (LC50 = 0.13 μg/ml). The surface hydroxylation dramatically reduced the toxicity, as did the quenching of oxidative stress
with glutathione added to the medium and exposure under dim light (Isaacson et al.
2017; Usenko et al. 2007, 2008; Zhu et al. 2007b). Carbon black was safe, at least
in experimental conditions adopted in the work of Cheng et al. (2007). The toxicity
of carbon nanotubes, single-, di-, or multi-walled, was moderate. In embryos
exposed from the 2-cell stage, they were distributed in all the cells of the blastoderm, and were excluded from the yolk cells. If injected into the embryonic circulation, they persisted after hatching, the complete clearance requiring 96 hours;
however, the germ cells of the embryo were not damaged, and the adult developed
normal gametes (Cheng et al. 2009). Instead, aggregates in unstable solution were
larger than the pores of the chorion; the nanotubes being therefore unable to reach
the embryo, the observed toxicity was attribute to the ions of heavy metals present
in a residual of the production (Cheng et al. 2007). Pegylation did not improve the
stability of single-walled carbon nanotubes, which retained a certain degree of toxicity without reaching the 50% of mortality or of malformation (Cordeiro et al.
2018). Delayed hatching and growth, pericardial edema, and malformations of the
caudal fin appeared after exposure to at least 60 μg/ml. Their toxicity increased if
the length of the tubes was reduced by prolonged sonication (Asharani et al. 2008;
Cheng et al. 2007; Cheng and Cheng 2012; Liu et al. 2014). A more detailed investigation demonstrated that the nanosheets enveloped the chorion, blocked the pores,
and induced severe hypoxia. Consequently, dose-dependent mitochondrial damage,
apoptosis, delayed hatching, and multiple malformations followed (Chen et al.
2015). Some carbon-based nanoparticles were intended as fluorescent probes for
imaging, such as graphene and carbon quantum dots, and nanodiamonds. All performed well in the zebrafish embryo, with null or low toxicity, according to the
authors (Lin et al. 2016; Wang et al. 2015; Xu et al. 2014b). Moreover, in vivo studies suggested that the lethal and theratogenic effects in mammals were much more
severe than those induced in the zebrafish (Ema et al. 2016).
The zebrafish embryonic test performed well to assess the toxicity of metal
nanoparticles. The exposure to gold was safe for spherical nanoparticles, while
nanorods had a dose-dependent lethality (LC50 < 0.01 nM). Coating with organic
polymers enhanced the bioavailability and the toxicity, with some exception, such
3 Safety and Utility of Nanomaterials on Reproduction and Development: An Update…
and Ward 2018; Jia et al. 2019; OECD 2013; Piersma 2011) (Table 5.1). Recently,
the zebrafish embryonic test was also standardized for testing metallic nanomaterials
(Pecoraro et al. 2017) and to assess the biodistribution of polystyrene nanoparticles
(nanoplastics) in the developing embryo (Lee et al. 2019; van Pomeren et al. 2017a).
The test is versatile, performing well to assess the toxicity and the embryotoxicity
in pharmacology as in ecotoxicology, requires small quantities of nanomaterials, is
reproducible, predictive, highly standardized, and easy to perform also in automated
systems. Herein, we present a synthetic overview of the results.
Among the alternative methods for embryotoxicity, the zebrafish embryonic test
was the most used to test the carbon-based nanomaterials. The exposure to buckminsterfullerene, such as C60, C70, and C98, induced excess of mortality and heart
and caudal fin malformations at doses lower than 1.5 μg/ml. concentration inducing
50% lethality in the sample was very low (LC50 = 0.13 μg/ml). The surface hydroxylation dramatically reduced the toxicity, as did the quenching of oxidative stress
with glutathione added to the medium and exposure under dim light (Isaacson et al.
2017; Usenko et al. 2007, 2008; Zhu et al. 2007b). Carbon black was safe, at least
in experimental conditions adopted in the work of Cheng et al. (2007). The toxicity
of carbon nanotubes, single-, di-, or multi-walled, was moderate. In embryos
exposed from the 2-cell stage, they were distributed in all the cells of the blastoderm, and were excluded from the yolk cells. If injected into the embryonic circulation, they persisted after hatching, the complete clearance requiring 96 hours;
however, the germ cells of the embryo were not damaged, and the adult developed
normal gametes (Cheng et al. 2009). Instead, aggregates in unstable solution were
larger than the pores of the chorion; the nanotubes being therefore unable to reach
the embryo, the observed toxicity was attribute to the ions of heavy metals present
in a residual of the production (Cheng et al. 2007). Pegylation did not improve the
stability of single-walled carbon nanotubes, which retained a certain degree of toxicity without reaching the 50% of mortality or of malformation (Cordeiro et al.
2018). Delayed hatching and growth, pericardial edema, and malformations of the
caudal fin appeared after exposure to at least 60 μg/ml. Their toxicity increased if
the length of the tubes was reduced by prolonged sonication (Asharani et al. 2008;
Cheng et al. 2007; Cheng and Cheng 2012; Liu et al. 2014). A more detailed investigation demonstrated that the nanosheets enveloped the chorion, blocked the pores,
and induced severe hypoxia. Consequently, dose-dependent mitochondrial damage,
apoptosis, delayed hatching, and multiple malformations followed (Chen et al.
2015). Some carbon-based nanoparticles were intended as fluorescent probes for
imaging, such as graphene and carbon quantum dots, and nanodiamonds. All performed well in the zebrafish embryo, with null or low toxicity, according to the
authors (Lin et al. 2016; Wang et al. 2015; Xu et al. 2014b). Moreover, in vivo studies suggested that the lethal and theratogenic effects in mammals were much more
severe than those induced in the zebrafish (Ema et al. 2016).
The zebrafish embryonic test performed well to assess the toxicity of metal
nanoparticles. The exposure to gold was safe for spherical nanoparticles, while
nanorods had a dose-dependent lethality (LC50 < 0.01 nM). Coating with organic
polymers enhanced the bioavailability and the toxicity, with some exception, such
3 Safety and Utility of Nanomaterials on Reproduction and Development: An Update…