Specific nanotoxicity of graphene oxide during zebrafish embryogenesis

Abstract

Graphene oxide (GO) has shown great potential for biological, medical, energy and electronic applications. As a consequence of these diverse applications, GO release into the ecosystem is inevitable; however, the corresponding risks are largely unknown, particularly with respect to the critical period of embryogenesis. This study revealed that GO adhered to and enveloped the chorion of zebrafish embryos mainly via hydroxyl group interactions, blocked the pore canals of the chorionic membrane, and caused marked hypoxia and hatching delay. Furthermore, GO spontaneously penetrated the chorion, entered the embryo via endocytosis, damaged the mitochondria and primarily translocated to the eye, heart and yolk sac regions, which are involved in the circulatory system of zebrafish. In these organs, GO induced excessive generation of reactive oxygen species and increased oxidative stress, DNA damage and apoptosis. Graphene oxide also induced developmental malformation of the eye, cardiac/yolk sac edema, tail flexure and heart rate reduction. In contrast to the common dose-effect relationships of nanoparticles, the adverse effects of GO on heart rate and tail/spinal cord flexure increased and then decreased as the GO concentration increased. These findings emphasize the specific adverse effects of GO on embryogenesis and highlight the potential ecological and health risks of GO.

• Hatching delay
• malformation
• mitochondrial dysfunction
• oxidative stress
• uptake

Declaration of interest

The authors declare no competing financial interests.

This work was financially supported by the Ministry of Science and Technology of China as a water specific project (grant No. 2012ZX07501002-001), the Ministry of Education of China (grant No. IRT 13024), the National Natural Science Foundation of China (grant Nos. 21307061 and 21037002), the Tianjin Natural Science Foundation (grant No. 14JCQNJC08900), the Doctoral Program of Higher Education of China (grant No. 2013003112016), and the Postdoctoral Science Foundation of China (grant No. 2014M550138).

Supplementary material available online

Supplementary Figures S1-18

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