In Vitro Study: Synthesis and Evaluation of Fe₃O₄/CQD Magnetic/Fluorescent Nanocomposites for Targeted Drug Delivery,...

In the present study, first, Fe₃O₄ nanoparticles were functionalized using glutaric acid and then composited with CQDs. Doxorubicin (DOX) drug was loaded to evaluate the performance of the nanocomposite for targeted drug delivery applications. The XRD pattern confirmed the presence of characteristic peaks of CQDs and Fe₃O₄. In the FTIR spectrum, the presence of carboxyl functional groups on Fe₃O₄/CQDs was observed; DOX (positive charge) is loaded onto Fe₃O₄/CQDs (negative charge) by electrostatic absorption. FESEM and AFM images showed that the particle sizes of Fe₃O₄ and CQDs were 23-75 and 1-3 nm, respectively. The hysteresis curves showed superparamagnetic properties for Fe₃O₄ and Fe₃O₄/CQDs (57.3 and 8.4 emu/g). The Fe₃O₄ hysteresis curve showed superparamagnetic properties (Ms and Mr: 57.3 emu/g and 1.46 emu/g. The loading efficiency and capacity for Fe₃O₄/CQDs were 93.90% and 37.2 mg DOX/g MNP, respectively. DOX release from Fe₃O₄/CQDs in PBS showed pH-dependent release behavior where after 70 h at pH 5 and 7.4, about 50 and 21% of DOX were released. Fluorescence images of Fe₃O₄/CQD-treated cells showed that Fe₃O₄/CQDs are capable of labeling MCF-7 and HFF cells. Also, T₂-weighted MRI scans of Fe₃O₄/CQDs in water exhibited high r₂ relaxivity (86.56 mM^-1 S^-1). MTT assay showed that DOX-loaded Fe₃O₄/CQDs are highly biocompatible in contact with HFF cells (viability = 95%), but they kill MCF-7 cancer cells (viability = 45%). Therefore, the synthesized nanocomposite can be used in MRI, targeted drug delivery, and cell labeling.