Investigating of the anticancer activity of salen/salophen metal complexes based on graphene quantum dots: Induction of apoptosis as part of biological activity.

This research work is the first report on the synthesis and stabilization of [Fe-Salophen] and [Fe-Salen] complexes by two methods of surface modification and anchoring of synthesized Schiff base ligand on the surface of graphene quantum dots (GQDs). The GQDs contain oxygenated functional groups that can act as non-radiative electron-hole recombination centers. Therefore removing these oxygen functional groups may improve quantum yield by reducing or deactivating the surface. In this work, GQDs with the amine functional group were synthesized with a quantum yield of 37.48%. The physicochemical properties of GQDs were investigated by Ultraviolet-visible (UV-Vis) and fluorescence spectroscopies, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Powder X-ray diffraction (PXRD), Transmission electron microscope (TEM). The synthesis of GQDs-[Fe-Salen] and GQDs-[Fe-Salophen] was evaluated by FT-IR, Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Energy dispersive X-Ray analysis (EDX) analyses. Then, using MTT- assay, annexin V-FITC/PI, DAPI staining and cellular uptake assays, the biochemical activity of these complexes on the MCF7 cell line was investigated. The results shows that GQDs-[Fe-Salen] and GQDs-[Fe-Salophen] affect the survival of MCF7 cancer cells and, by nuclear fragmentation cause 35.77% and 19.41% of early apoptosis in cells, respectively. Also was found cellular uptake of GQDs-[Fe-Salen] is higher than that of GQDs-[Fe-Salophen].

Graphene quantum dots based MnFe2O4@SiO2 magnetic nanostructure as a pH-sensitive fluorescence resonance energy transfer (FRET) system to enhance the anticancer effect of the drug.

Among the various methods of targeted drug delivery, magnetic nanoparticles been considered for a long time due to local drug delivery, reduction of side effects, and controlled drug release. In this work, fluorescence resonance energy transfer (FRET) system MnFe2O4@SiO2@ graphene quantum dots /DAU with 28.02 emu g-1 magnetism was prepared as pH-sensitive nanoplatform to enhance the anti-cancer effect of daunorubicin (DAU) drug (in the obtained FRET system, DAU act as acceptor molecule and graphene quantum dots act as donor molecule). The efficiency of the drug loaded on the nanoplatform in vitro is 78 %. DAU drug release from nanoplatform at pHs of 7.4 and 5.5 during 48 h is 21 % and 60 %, respectively. Release sensitive to pH facilitates the application of prepared nanoplatform for DAU delivery. The results of MTT-assay and annexin V-FITC/PI show that MnFe2O4@SiO2@ graphene quantum dots /DAU induces cell apoptosis by inhibiting the growth of more than 95 % of MCF-7 cells. Also, according to the results, it was found that MnFe2O4@SiO2@ graphene quantum dots /DAU can inhibit 66.65 % cell cycle in the sub-G1 phase. Therefore, due to the anti-cancer activity of MnFe2O4@SiO2@ graphene quantum dots /DAU, this biological nanoscale can be considered a candidate for drug delivery.