Development toxicity of functionalized single-walled carbon nanotubes on rare minnow embryos and larvae

Carbon nanotubes (CNTs) are widely used in industrial and commercial applications, but few studies systematically evaluate their developmental toxicity on aquatic organism. Using rare minnow (Gobiocypris rarus) at early life stages as experimental models, developmental toxicity of functionalized single-walled CNTs (SWCNTs) was investigated following exposure to 0-320 mg/L for 144 h. Results revealed that significantly increased in mortality and malformation was only observed after hatching. Decreased body length, heart rate and swimming speed provide a concentration-dependent manner on larvae; values of 144 h LC50 and EC50 were 140.8 and 109.8 mg/L, respectively. Antioxidant enzyme activities (superoxide dismutase, catalase and glutathione S-transferase) and antioxidant enzyme related mRNA expressions were significant changed; cell apoptosis activities (caspase-3, -8, -9) and cell apoptosis related mRNA expressions were significant up-regulated; reactive oxygen species and DNA damage were significantly induced when the concentration of SWCNTs above 100 mg/L. Fluorescence and electron microscopy sliced observation show that SWCNTs were well dispersed in larvae within 0.5 h, eventually cleared from the larvae at 144 h. This is the first study to define uptake kinetics and to focus on behavioral consequences, physiological changes and mRNA expression following SWCNTs exposure in the early life stages of fish. The results obtained in the present study demonstrated that functionalized SWCNTs have the potential to affect aquatic life when released into the aquatic environment and reached high concentration. In the increasing economical context of SWCNTs, complementary studies must be undertaken, especially including mechanistic and environmental investigations.