Fig. 1

Characterization of GQDs. A TEM imaging of GQDs, showing a diameter around 10 nm. Scalebar 50 nm. B Light scattering measurements of GQDs, depicting a hydrodynamic radius around 6 nm. C Absorbance of GQDs in the range between 230 and 800 nm. D Fluorescence intensity of GQDs by exciting from 260 to 480 nm and recording emission from 300 to 700 nm. E AFM images of GQDs and F representative line profile of the image. G FTIR spectroscopy showing typical peaks of GQDs functionalized with carboxyl groups. H, I Biocompatibility of GQDs on glioblastoma cells and human fibroblasts, respectively, at concentrations ranging from 50 to 250 μg/mL. Results are reported as % of control (untreated) cells