In vivo toxicity assessment of angiogenesis and the live distribution of nano-graphene oxide and its PEGylated derivatives using the developing zebrafish embryo

The toxicity of nano-graphene oxide (NGO) on development and angiogenesis was evaluated using zebrafish embryos as in vivo model system. Microinjection of NGO resulted in gross morphological defects in a dose-dependent manner partly due to the induction of apoptosis, whereas coating NGO derivatives with polyethylene glycol (PEG), a biocompatible polymer significantly attenuated its toxicity. NGO also caused abnormal branching and mispatterning of developing trunk blood vessels monitored by endothelial cell-specific fluorescent transgenic zebrafish, presumably via Vascular Endothelial Growth Factor and Notch pathways, key signaling pathways for normal angiogenic process. Interestingly, Alexa568 conjugated, PEG-coated NGO (NGO-A568) still caused angiogenic defects to the similar degree as NGO did, suggesting differential toxic effects of nanomaterials on different developmental processes. Confocal microscopy imaging of NGO- and NGO-A568-injected embryos visualized its live distribution throughout the body including the cranial vasculature. The broader utilization of embryonic zebrafish combined with in vivo, real-time, high-resolution imaging is warranted for assessing the properties of nanomaterials.