Gelatin-assisted fabrication of reduced nanographene oxide for dual-modal imaging of melanoma cells.

In this work we report a gelatin-based, simple two-steps approach for fabrication of reduced graphene oxide (rGO-GEL) possessing high stability and biocompatibility, as novel label-free intracellular contrast agents. Gelatin, a biopolymer that is known for its versatility, was employed not only to biocompatibilize the rGO, but also to prevent the aggregation of the GO nanosheets during the reduction process. To confirm the successful reduction process and the attachment of the gelatin to the rGO nanosheets, we employed multiple spectroscopic analyses such as FT-IR, Raman, UV-VIS and photoluminescence, while the morphology and the lateral dimensions of the resulting hybrid rGO-GEL were investigated by Scanning-Transmission Electron Microscopy (STEM). Cellular toxicity test proved that the rGO-GEL nanoflakes are nontoxic for melanoma B16-F10 cells, even at high concentrations. Finally, the intracellular tracking after 24 h of treatment was performed by non-invasive Super-resolution re-scan confocal microscopy as well as Confocal Raman imaging, thus implementing our nanoflakes as a suitable contrast agent candidate for cellular imaging of interest.