MR/SPECT Imaging Guided Photothermal Therapy of Tumor-Targeting Fe@Fe3O4 Nanoparticles in Vivo with Low Mononuclear Phagocyte Uptake

The I-125-c(RGDyK) peptide PEGylated Fe@Fe3O4 nano particles (I-125-RGD-PEG-MNPs) with the average hydrodynamic diameter of 40 nm as a novel multifunctional platform were developed for tumor-targeting MR/SPECT imaging guided photothermal therapy in vivo. On the alpha(v)beta(3)-positive U87MG glioblastoma xenograft model, the signals of tumor from T-2-weighted MR and SPECT imaging were much higher than those in the blocking group at 6 h post injection (p.i.) of RGD-PEG-MNPs and I-125-RGD-PEG-MNPs intravenously, respectively. The pharmacokinetics and biodistribution were analyzed quantitatively by gamma counter ex vivo. The fact suggested that RGD-PEG-MNPs exhibited excellent targeting property and low mononuclear phagocyte uptake. At 6 h p.i. for I-125-RGD-PEG-MNPs, the maximum uptake of 6.75 +/- 1.24% of the percentage injected dose per gram (ID/g) was accumulated in the tumor. At 48 h p.i., only 1.11 +/- 0.21% and 0.16 +/- 0.09% ID/g were accumulated in the liver and spleen, respectively. With the guidance of MR/SPECT imaging, the multifunctional nanoparticles achieved a good photothermal therapeutic efficacy in vivo.