Long-term exposure to thiolated graphene oxide in the range of μg/L induces toxicity in nematode Caenorhabditis elegans.

The in vivo toxicity and translocation of thiolated graphene oxide (GO-SH) are still largely unclear. We hypothesized that long-term exposure to GO-SH may cause the adverse effects on environmental organisms. We here employed in vivo assay system of Caenorhabditis elegans to investigate the possible toxicity and translocation of GO-SH after long-term exposure. In wild-type nematodes, we observed that prolonged exposure to GO-SH at concentrations>100μg/L resulted in the toxicity on functions of both primary targeted organs such as the intestine and secondary targeted organs such as the neurons and the reproductive organs. The severe accumulation of GO-SH was further detected in the body of wild-type nematodes. The translocation of GO-SH into secondary targeted organs such as reproductive organs through intestinal barrier might be associated with the enhancement in intestinal permeability in GO-SH exposed wild-type nematodes. Prolonged exposure to GO-SH (100μg/L) decreased the expression of gas-1 encoding a subunit of mitochondrial complex I, and mutation of gas-1 caused the formation of GO-SH toxicity at concentration>10μg/L and more severe accumulation of GO-SH in the body of animals. Therefore, our results confirm the possibility for prolonged exposure to GO-SH in inducing adverse effects on nematodes. Our data highlight the potential adverse effects of GO-SH in the range of μg/L on environmental organisms after long-term exposure.