▎ 摘　　要

Curcumin (as a natural reductant material) was utilized for green reduction and functionalization of chemically exfoliated graphene oxide (GO) sheets. The pi-pi attachment of the curcumin molecules onto the curcumin-reduced graphene oxide (rGO) sheets was confirmed by Raman and Fourier transform infrared spectroscopies. Zeta potential of the GO sheets decreased from about -40 mV to -20 mV, after the green reduction and functionalization. The probable cytotoxicity of the curcumin-rGO sheets was studied through their interactions with two human breast cancer cell lines (MDA-MB-231 and SKBR3 cell lines) and a normal cell line (mouse fibroblast L929 cell line). The curcumin-rGO sheet with concentrations <70 mu g/mL in the cell culture medium, not only exhibited no significant toxicity and/or cell morphological changes, but also caused some cell growths (similar to 25% after 48 h incubation time). Nevertheless, at 70 mu g/mL, initiation of some cell morphological changes was observed. At higher concentrations (e.g., 100 mu g/mL), some slight cytotoxic effects (resulting in similar to 15-25% cell destruction) were detected by MTT assay. In addition, the interaction of the rGO sheets and cells resulted in apoptosis as well as morphological transformation of the cells (from elongated to roundup morphology). These results indicated the concentration-dependent toxicity of functionalized-rGO nanomaterials (here, curcumin-rGO) at the threshold concentration of similar to 100 mu g/mL. (C) 2015 Elsevier B.V. All rights reserved.