This study reports a new procedure for utilizing 5fluorouracil (5-Fu)-loaded polycaprolactone (PCL)/chitosan-covered magnetite nanographene oxide (5-Fu/SPION/NGO@PCL−LMWC) as a platform for synergistic thermo−chemotherapy. In fact, superparamagnetic iron oxide nanoparticles/nanographene oxide (SPION/ NGO) nanoparticles can be coated with copolymers PCL/chitosan to attain better colloidal stability in the biological environment. Nanoparticles were synthesized and characterized for their size, surface charge, X-ray patterns, polymer content, and in vitro heat-triggered release. In vitro cytotoxic effects of nanoparticles on CT-26 cells were assessed with an MTT assay and real-time polymerase chain reaction. In vivo tumor growth inhibition was evaluated on an allograft mouse model of CT-26 cells. Tumor-bearing mice were injected with 5-Fuloaded nanoparticles intravenously, and then, the targeted delivery was amplified using a magnetic field and finally exposed to an alternating magnetic field (AMF) (40 A/m, 13.56 MHz), during which the tumor site temperature increased to 43 °C. By using an infrared camera, we managed to heat the nanoparticles up to a constant temperature between 42.5 and 43.5 °C, with a tolerance ±0.03 °C. Finally, in vitro results showed that 5-Fu-loaded nanoparticles combined with AMF hyperthermia significantly reduced the plating efficiency of the cells (P < 0.01) and increased the Bax/Bcl-2 ratio (1.42 times, P < 0.01) compared with those achieved with each one alone. Furthermore, in vivo results demonstrated that the treatment of 5-Fu-loaded nanoparticles combined with the AMF diminished the growth of CT-26 tumor cells and increased the life span of the tumor-bearing mice (P < 0.001) by thermal energy deposition compared to that of the free 5-Fu drug. Also, the high level of accumulation of the nanoparticles within the tumor site was easily monitored with magnetic resonance imaging. It was concluded that the multifunctional magnetic nanoparticles could be used as a promising nanocarrier platform for achieving concurrent goals, drug delivery, magnetic targeting, thermal-sensitizing, cell death induction, and real-time monitoring of response to treatment.

Therefore, PCL/CHI-SPION-NGO can deliver 5-Fu more efficiently into the CT26 cells.