Chemical interactions and ecotoxicity effects between graphene oxide and Lemna gibba

The features of Graphene Oxide (GO) could produce unexpected interactions with ecosystem, triggering negative effects on biota. In this work we evaluated the effects of two different GO samples (chemically synthesized GO(C) and electrochemically synthesized GO(E)) on Lemna gibba L., after incubation with different concentrations over a period of 21 days. The stress conditions were evidenced by the measurements of frond number, fresh weight, dry weight, dry/fresh weight ratio, and inhibition of growth rate. Furthermore, a morphological characterization was also carried out to verify the mechanical effects on L. gibba plants of these two GO. Results demonstrated that the smallest GO(E) nano sheets were very well dispersed on L. gibba fronds than GO(C). This effect could be explained considering the lower GO(E) functionalization degree and, as a result, a less electrostatic adhesion among nanosheets. The presence of electrically charged functionalities mainly provides electrostatic interactions with plants causing growth inhibition as shown by GO(C).