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

[Display omitted] •This study is the first report on the synthesis of MnFe2O4@SiO2@GQDs/DAU nanoprobes with the ability to deliver DAU anticancer drug and image simultaneously.•The MnFe2O4@SiO2@GQDs/DAU nanoprobe has a greater anti-cancer effect than the free DAU drug by inhibiting 95% growth of MCF-7 cells.•The synthesized nanoprobe cause induces cell apoptosis and inhibits cell cycle in the sub-G1 stage.•Examination of in vitro loaded DAU release showed that the amount of drug released at acidic pH (cancer cell environment) was higher than neutral pH (normal cell environment). 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.