Toxicity of single‐wall carbon nanotubes functionalized with polyethylene glycol in zebrafish (Danio rerio) embryos

Abstract

Single-wall carbon nanotubes functionalized with polyethylene glycol (SWCNT-PEG) are promising materials for biomedical applications such as diagnostic devices and controlled drug-release systems. However, several questions about their toxicological profile remain unanswered. Thus, the aim of this study was to investigate the action of SWCNT-PEG in Danio rerio zebrafish embryos at the molecular, physiological and morphological levels. The SWCNT used in this study were synthesized by the high-pressure carbon monoxide process, purified and then functionalized with distearoyl phosphatidylethanolamine block copolymer-PEG (molecular weight 2 kDa). The characterization process was carried out with low-resolution transmission electron microscopy, thermogravimetric analysis and Raman spectroscopy. Individual zebrafish embryos were exposed to the SWCNT-PEG. Toxic effects occurred only at the highest concentration tested (1 ppm) and included high mortality rates, delayed hatching and decreased total larval length. For all the concentrations tested, the alkaline comet assay revealed no genotoxicity, and Raman spectroscopy measurements on the histological slices revealed no intracellular nanotubes. The results shown here demonstrate that SWCNT-PEG has low toxicity in zebrafish embryos, but more studies are needed to understand what mechanisms are involved. However, the presence of residual metals is possibly among the primary mechanisms responsible for the toxic effects observed, because the purification process was not able to remove all metal contamination, as demonstrated by the thermogravimetric analysis. More attention must be given to the toxicity of these nanomaterials before they are used in biomedical applications. Copyright © 2016 John Wiley & Sons, Ltd.

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.…”

“…As mentioned above, another problem in toxicology studies of CNTs is the presence of impurities. Girardi et al (2017) established that the presence of metal impurities might be the principal cause of toxicity because the purification process is not able to remove them completely.…”

Recent advances in bioactive 1D and 2D carbon nanomaterials for biomedical applications

“…120 However, a recent study by Girardi et al suggests that embryonically applied PEGylated SWCNTs did not cause any genotoxicity in zebrafish between the concentration values of 0.1 and 1 ppm. 121…”

Recent Trends of Nano-material as Antimicrobial Agents

“…It is difficult to determine physiologically relevant cytotoxicity due to difference in toxicity parameters during the study by different groups. To understand the toxic effect several biological models includes cell lines, aquatic embryonic zebrafish (Danio rerio), and whole-animal tests such as rodents (mice/rat) (Girardi et al 2017;Griffitt et al 2007).…”