In vivo toxicology of carbon dots by 1H NMR-based metabolomics

Owing to the promising applications of C-dots in biomedical engineering, concerns about their safety have drawn increasing attention recently. In this study, mice were intraperitoneally injected at different C-dot concentrations (0, 6.0, 12.0 and 24.0 mg kg−1) once every 2 days for 30 days. A 1H NMR-based metabolic approach supplemented with biochemical analysis and histopathology was used for the first time to explore the toxicity of C-dots in vivo. Histopathological inspection revealed that C-dots did not induce any obvious impairment in tissues. Biochemical assays showed no significant alterations of most measured biochemical parameters in tissues and serum, except for a slight reduction of the albumin level in serum as well as AChE activity in the liver and kidneys. Orthogonal signal correction-partial least squares-discriminant analysis (OSC-PLS-DA) of NMR profiles supplemented with correlation network analysis and SUS-plots disclosed that C-dots not only triggered the immune system but also disturbed the function of cell membranes as well as the normal liver clearance, indicating that the 1H NMR based metabolomics approach provided deep insights into the toxicity of C-dots in vivo and gained an advantage over traditional toxicological means, and should be helpful for the understanding of its toxic mechanism.