Hexavalent chromium amplifies the developmental toxicity of graphene oxide during zebrafish embryogenesis

• Published in: Ecotoxicology and environmental safety 2021-01, Vol.208, p.111487, Article 111487
• Main Authors: Chen, Yuming, Li, Jitong, Zhou, Qixing, Liu, Zhijie, Li, Qiong
• Format: Article
• Language: English
• Subjects: Animals; Chromium - toxicity; Danio rerio; Embryo, Nonmammalian - drug effects; Embryonic Development - drug effects; Graphite - toxicity; Heavy metals; Joint toxicity; Nanomaterials; Nanoparticles - toxicity; Teratogenicity; Toxicity Tests; Water Pollutants, Chemical - toxicity; Zebrafish - embryology
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2020.111487

Combined toxicity is a critical issue in risk assessment of contaminants. However, very little is known about the joint effects of graphene oxide (GO, a crucial 2-dimensional carbon material) and hexavalent chromium (Cr6+, a widespread heavy metal), particularly with respect to the critical period of embryogenesis. In this study, the combined toxicity of GO and Cr6+ was evaluated through embryo-larval toxicity test in Danio rerio (zebrafish). Results indicated that the co-exposure of Cr6+ (1 mg/L) and GO (0.01 mg/L) inhibited hatching and spontaneous movement of embryos, but no significant changes were found in the single Cr6+ or GO group. Compared with the single GO or Cr6+ exposure, their co-exposure (GO+Cr6+) significantly enhanced the teratogenicity in a concentration-dependent pattern, and the spinal curvature was observed as the main deformity. GO+Cr6+ changed the protein secondary structures of embryos result of the generation of ROS and oxidative stress. The degradations of vertical myosepta and cartilages were observed in co-exposure group, suggesting that GO+Cr6+ disrupted the development of musculoskeletal system. The genes col11a1a, col2a1a and postnb were down-regulated but the genes acta1b and mmp9 were up-regulated by GO+Cr6+. The interactions between Cr6+ and GO demonstrated that the morphology, structure, and surface properties of GO were modified by Cr6+. The enhanced defects and O-containing groups of GO could trap more β-sheets, induced oxidative stress, disturbed the development of skeletal muscles and cartilages in zebrafish. These data suggested that GO+Cr6+ enhanced their joint toxicity due to the variation of nanoparticle properties. This finding is important for assessing the ecological risk of graphene family nanomaterials in the natural environment. •Interactions between Cr6+ and GO were investigated.•Cr6+ modified the morphology, structure, and surface properties of GO.•Cr6+ enhanced the teratogenicity of GO.•Co-exposure disturbed skeletal musculoskeletal development.•The mechanisms of the combined toxicity were studied.