Synergistic effects of graphene quantum dots nanocarriers and folic acid targeting agent on enhanced killing of breast cancer cells by tamoxifen

In this study, a new targeted and controlled-release drug delivery system based on graphene quantum dots (GQDs) was fabricated. The fluorescent GQDs were synthesized via an environmentally-friendly chemical oxidation method, using graphene oxide (GO) as a precursor and hydrogen peroxide and ammonia solution as oxidants. Folic acid (FA), as a targeting agent, was bound to GQDs through strong amide covalent bindings, and tamoxifen (TMX), as a hydrophobic anticancer drug, was non-covalently attached to the nanocarrier via pi-pi stacking bonds. The as-prepared GQDs and TMX/FA-GQDs were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), UV/Vis spectroscopy (UV/Vis), and photoluminescence spectroscopy (PL). The resulting TMX/GQDs demonstrated pH-sensitive release behaviour with an overall release of 85% and 58% at pH 5.5 and 7.4, respectively, after 120 h. Also, the MTT assay test performed on MCF-7 cells presented negligible toxicity of the nanocarriers, even at high concentrations. At the same time, the targeted nanocarrier, TMX/FA-GQDs, showed much more toxicity towards MCF-7 cells than the non-targeted one and free TMX. The schematic shows pH-sensitive release behaviour of GQDs loaded by TMX (TMX/GQDs) and higher cytotoxicity of GQDs functionalized with FA and loaded by TMX (TMX/FA-GQDs) than the non-functionalized one. image