Rational Design of GO-Modified Fe₃O₄/SiO₂ Nanoparticles with Combined Rhenium-188 and Gambogic Acid for Magnetic Target Therapy

Peanutlike magnetic-fluorescent Fe 3 O 4 /SiO 2 nanoparticles, with an effective dynamic diameter of 180 nm, were synthesized via EuO + doping and coupling of two Fe 3 O 4 cores and reassembling through the solvothermal process. Spherical pure Fe 3 O 4 /SiO 2 nanoparticles with an effective dynamic diameter of 230 nm were also prepared for comparison. We designed graphene oxide (GO)-modified core–shell Fe 3 O 4 /SiO 2 nanoparticles as a nanocarrier for loading gambogic acid (GA) following labeling with radioisotope rhenium-188. We also performed GA loading and releasing on GA-loaded magnetic nanoparticles, in vivo biodistribution, and magnetic drug targeting therapy experiments. Results indicated that the GA-loaded magnetic nanoparticles demonstrate a clear pH-dependent drug release behavior, having a higher release rate in acidic environments. The in vivo biodistribution of the magnetic nanoparticles has morphologic dependency, and the peanutlike nanoparticles (PN-Fe 3 O 4 ) tend to accumulate more in the spleen, lung, and liver than in the spherical nanoparticles (S-Fe 3 O 4 ). The targeted therapy showed a higher efficacy of PN-Fe 3 O 4 in inhibiting tumor cell growth than the nontargeted therapy. The polyethyleneimine (PEI) grafting of PN-Fe 3 O 4 with amide bond was also designed to find an effective active targeting antitumor agent considering the fact that the PEI–GO conjugate has a higher GA load efficiency and the convergence effect.