Developmental toxicity of black phosphorus quantum dots in zebrafish (Danio rerio) embryos

Nanomaterials have attracted much attention in the biomedical field. Black phosphorus quantum dots (BPQDs) have shown great potential in biomedical applications, but their potential risks to biosafety and environmental stability have not been fully evaluated. In the present study, zebrafish (Danio rerio) embryos were exposed to 0, 2.5, 5 and 10 mg/L BPQDs from 2 to 144 h post-fertilization (hpf) to explore developmental toxicity. The results showed that exposure to BPQDs for 96 h induced developmental malformations (tail deformation, yolk sac edema, pericardial edema, and spinal curvature) in zebrafish embryos. ROS and antioxidant enzyme activities (CAT, SOD, MDA and T-AOC) were substantially altered and the acetylcholinesterase (AChE) enzyme activity was significantly decreased in the BPQDs exposed groups. Locomotor behavior was inhibited after BPQDs exposure for 144 h in zebrafish larvae. A significant increase in 8-OHdG content indicates DNA oxidative damage in embryos. In addition, obvious apoptotic fluorescence signals were detected in the brain, spine, yolk sac and heart. At the molecular level, the mRNA transcript levels of key genes related to skeletal development (igf1, gh, MyoD and LOX), neurodevelopment (gfap, pomca, bdnf and Mbpa), cardiovascular development (Myh6, Nkx2.5, Myl7, Tbx2b, Tbx5 and Gata4) and apoptosis (p53, Bax, Bcl-2, apaf1, caspase-3 and caspase-9) were abnormal after BPQDs exposure. In conclusion, BPQDs induced morphological malformations, oxidative stress, locomotor behavior disorders, DNA oxidative damage and apoptosis in zebrafish embryos. This study provides a basis for further study on the toxic effects of BPQDs.