Characterization of Lyophilized-Sonicated Graphene Oxide (L-SGO) and Ecotoxicity Assessment on Biological Models

GAGNTEN, A.M; SCHMUCK, J; RENO, U; VAZQUEZ, J; RONDAN, W; REGALDO, L; CHAMPI, A

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

Society of Environmental Toxicology and Chemistry

Graphene Oxide (GO) is a highly oxidized form of graphene and an emerging nanomaterial with a large surface area, excellent strength, and other mechanical properties, while maintaining high ductility, flexibility and hydrophilicity being widely used for technological and commercial uses. These unique properties facilitate the adhesion of GO to cell surfaces; L-SGO ecotoxicity is largely unknown. The current study provides a structural and chemical analysis of L-SGO by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), RAMAN Spectroscopy and XPs Diffraction, and ecotoxicity assessment on 3 biological models. GO was synthesized by the modified Hummer method, from natural graphite powder and NaNO3, mixed with H2SO4, H2O2 stirred for 5 h, then washed with HCL, deionized water, and ethanol until neutral pH. The solution was lysed and dispersed in water and sonicated for 3 h to obtain graphene oxides in the form of sheets. The potential toxicity of 0.1, 1.0, 10, and 100 mg L-1 L-SGO and a control (without L-SGO) was previously evaluated on C. vulgaris, L. sativa and A. cepa. Graphene oxide showed a sheet structure (573.2 ±324 nm) with irregular folds and wrinkles on its edges and surface. In the L-SGO leaves predominated Carbon and Oxygen, corroborated by Raman Spectroscopy: D, G, 2D and D+D bands characteristic of GO. XPS measurements of L-SGO showed a 29.05% O and 70.95% C concentration. No significant differences were found in C. vulgaris density, cell diameter, biovolume, or pigment concentration between the control and all treatments with L-SGO. Still, there was inhibition of the growth rate at the highest concentration. SEM images in control show intact cells; in 0.1 and 10 mg L-1 the cells remain undamaged, but a large number of L-SGO sheets were observed on cell surfaces. Conversely, in 100 mg L- 1 cells are destroyed and form bulks. Similar results were obtained from L.sativa imaging by SEM. L. sativa tests showed no significant differences (p>0.05) between the control and the concentrations tested in radicle elongation, only significant differences (p