Evaluating the toxicity of PEGylated multiwalled carbon nanotubes in zebrafish embryos: insights for biomedical and environmental safety

Polyethylene glycol-Multiwalled carbon nanotubes (PEG-MWCNTs) hold significant potential for biomedical applications, including diagnostics and controlled drug delivery. However, their toxicity allied to the synthesis process remains a critical concern. Residual metal impurities from the synthesis process are suggested as potential contributors to the observed toxicity. This study evaluates the cellular, genomic, and morphological toxicity of PEG-MWCNTs in zebrafish embryos. MWCNTs were synthesized via chemical vapor deposition, purified with nitric acid, and functionalized with PEG-6000. They were further characterized by high-resolution transmission electron microscopy (TEM), zeta potential analysis, and FTIR spectroscopy. The different concentrations of PEG-MWCNT (0.01-10.24 mg/L) were used for acute toxicity testing in zebrafish embryos. The median lethal concentration (LC50) decreased over time, indicating increased toxicity with prolonged exposure. Toxic effects, including egg coagulation, yolk sac edema, pericardial edema, tail detachment, and delayed hatching, were observed at higher doses. Genotoxicity, assessed via the alkaline comet assay, revealed significant DNA damage at concentrations above 1.28 mg/L. Histological analysis further demonstrated cellular disruptions such as hyperemia, somite disorganization, and notochord deterioration. These findings can be utilized for further toxicity assessments, safe in vivo drug delivery, biomedical and environmental applications to ensure minimal ecological and health impacts.