Effect of carbon nanotubes on developing zebrafish (Danio Rerio) embryos

Abstract

The impact of carbon nanotubes (CNTs) on the aquatic environment was investigated by examining the properties of raw CNTs under several environmental conditions and using developing zebrafish (Danio rerio) embryos. The agglomerate size for single-walled CNTs (SWCNTs) was significantly larger at pH 11 or greater and was stable at temperatures from 4 to 40 degrees C and salinities from 0 to 30 ppt. Exposure to SWCNTs induced a significant hatching delay in zebrafish embryos between 52 to 72 h postfertilization (hpf) at concentrations of greater than 120 mg/L, but 99% of the exposed embryos hatched by 75 hpf. Double-walled CNTs also induced a hatching delay at concentrations of greater than 240 mg/L, but carbon black did not affect hatching at the concentrations tested. Molecular and cellular analysis showed that the embryonic development of the exposed embryos up to 96 hpf was not affected at SWCNT concentrations of up to 360 mg/L. Scanning-electron microscopic inspection showed that the size of the pores on the embryo chorion was nanoscaled and that the size of SWCNT agglomerates was microscaled or larger, indicating that the chorion of zebrafish embryos was an effective protective barrier to SWCNT agglomerates. The hatching delay observed in this study likely was induced by the Co and Ni catalysts used in the production of SWCNTs that remained at trace concentrations after purification. This study suggests that materials associated with raw SWCNTs (perhaps metal contaminants) have the potential to affect aquatic life when released into the aquatic environment.

Relation between biophysical properties of nanostructures and their toxicity on zebrafish

“…Wang et al (2016) found that bioaccumulation of MWCNTs was greater than that of SWCNTs and that embryos treated with SWCNTs presented severe malformations whereas embryos treated with MWCNTs presented normal development. In addition, Cheng et al (2007) and (Girardi et al 2017) reported a delay in the hatching rate of zebrafish embryos incubated with SWCNTs in a concentrationdependent manner. In contrast, working with a wide CNT concentration range that included the concentrations used by Cheng and Girardi, Bayat et al (2015) found no effects.…”

“…Table 1 describes the different functionalization and toxicological assays carried out in each CNT. Cheng et al (2007) described a delay in the hatching rate of zebrafish embryos incubated with SWCNTs and MWCNTs, with more marked effects by SWCNTs. Wang et al (2016) found that bioaccumulation of MWCNTs was greater than that of SWCNTs and that embryos treated with SWCNTs presented severe malformations whereas embryos treated with MWCNTs presented normal development.…”

“…CNTs can be synthesized by different methods, each of which leaves impurities that seem to have a significant effect on the biological response of zebrafish, affecting the evaluation of the toxicity of the nanomaterial (Farre et al 2009;Nayak et al 2010). In light of all the evidence, the critical step in evaluating the toxicology of a CNT is its physicochemical characterization, a first step indispensable to compare results between reports (Asharani et al 2008;Cheng et al 2009;Cheng and Cheng 2012;Cheng et al 2007). …”

Developmental toxicity and alteration of gene expression in zebrafish embryos exposed to PFOS

“…Therefore, it is feasible to select toxicological endpoints to find the genes that may be involved in toxicant exposure. Recently, zebrafish embryos have been employed for rapid and high-throughout screening of compounds for developmental toxicity and mechanisms of toxicant exposure, including β-naphthoflavone (Voelker et al, 2007), polybrominated diphenyl ethers (Lema et al, 2007), algal toxins (Berry et al, 2007), dioxins (Bello et al, 2004), polycyclic aromatic hydrocarbons (Incardona et al, 2005), pesticides , heavy metals (Chan and Cheng, 2003;Linbo et al, 2006) and carbon nanotubes (Cheng et al, 2007).…”

Low Doses of Pristine and Oxidized Single-Wall Carbon Nanotubes Affect Mammalian Embryonic Development

“…In such species it has been demonstrated that CNTs do not interfere with proper embryonic development, and the observed hatching delay might be ascribed to Ni and Co contaminants, rather than the CNTs themselves. 17 Despite the advantages of the zebrafish model, fish development and embryo morphology differ from that of mammals, and findings for one class cannot be automatically translated to the other. To our knowledge, no studies have been so far performed on the effects of CNTs on mammalian embryonic development, despite the high potential clinical and social relevance of this end point.…”