Tumor-targeted Gd-doped mesoporous Fe₃O₄ nanoparticles for T₁/T₂ MR imaging guided synergistic cancer therapy

Figures & data

Scheme 1. Schematic illustration of the preparation of DOX@Gd-MFe₃O₄ NPs and magnetic tumor targeted T₁/T₂ MR imaging guided synergistic cancer therapy.

Figure 1. Characterizations of Gd-MFe₃O₄ NPs: (A) TEM image of MFe₃O₄ NPs; (B) TEM image of Gd-MFe₃O₄ NPs; (C) size distribution of MFe₃O₄ and Gd-MFe₃O₄ NPs; (D) nitrogen adsorption–desorption isotherm of the MFe₃O₄ NPs; (E) XRD pattern of MFe₃O₄ NPs; (F) EDS analysis of Gd-MFe₃O₄ NPs; (G) XPS spectra of Gd-MFe₃O₄ NPs; (H) magnetization curve of the MFe₃O₄ and Gd-MFe₃O₄ NPs; (I) UV–-vis–NIR absorbance spectra of DOX, MFe₃O_4, Gd-MFe₃O_4, DOX@Gd-MFe₃O₄ NPs.

Figure 2. Photothermal effect of Gd-MFe₃O₄ NPs: (A) temperature change in MFe₃O₄ and Gd-MFe₃O₄ NPs suspension at the same concentration (0.25 mg/mL) under NIR laser irradiation (5 min, 1.5 W/cm²); (B) infrared thermal images of Gd-MFe₃O₄ NPs suspension of varying concentrations exposed to NIR laser (1.8 W/cm²) for 0–5 min. (C) Temperature elevation in Gd-MFe₃O₄ NPs suspension at gradient concentrations NIR laser irradiation (5 min, 1.5 W/cm²). (D) Temperature elevation in Gd-MFe₃O₄ NPs suspension (0.25 mg/mL) at different intensities of NIR laser irradiation. (E) Photothermal stability of Gd-MFe₃O₄ NPs suspension (0.25 mg/mL) under repeated NIR laser irradiation for four cycles.

Figure 3. In vitro DOX release from DOX@Gd-MFe₃O₄ NPs in the presence and absence of NIR laser (2 W/cm², 5 min). Values are expressed as mean ± SD (n = 3).

Figure 4. T₁ longitudinal and T₂ transverse relaxivities: (A) T₁ and T₂-weighted phantom images of Gd-MFe₃O₄ NPs using a 3.0 T MR scanner; (B) T₁ longitudinal relaxation rate of Gd-MFe₃O₄ NPs with different concentrations of Gd; (C) T₂ transverse relaxation rate of Gd-MFe₃O₄ NPs with different concentrations of Fe.

Figure 5. In vitro cellular uptake behavior of DOX@Gd-MFe₃O₄ NPs: (A) confocal microscopy images of the cellular uptake of DOX@Gd-MFe₃O₄ NPs (DOX= 5 μg/mL) 4T1 cells, scale bar = 20 μm. (B) Prussian blue staining of 4T1 cells in the presence and absence of magnetic field after 2 h incubation of Gd-MFe₃O₄ NPs with different concentrations (scale bar = 20 μm).

Figure 6. In vitro synergistic therapy for 4T1 tumor cells (A) Live/dead cells staining images of 4T1 cells after different treatments (0.25 mg/mL). The cells were co-stained with calcein AM and PI for live (green) and dead (red) cells, respectively. (B) Cell viabilities of 4T1 cells after different treatments with or without NIR. Values are expressed as mean ± SD (n = 4). (C) Cell viabilities of 4T1 cells after photothermal ablation with different NPs concentrations. Values are expressed as mean ± SD (n = 4).

Figure 7. (A) In vivo MR imaging tests. (A) T₁-weighted MR imaging of mice model with or without magnet after injection of Gd-MFe₃O₄ NPs at various time intervals; (B) T₂-weighted MR imaging of mice model in the presence and absence of magnetic field at 4 h after injection of Gd-MFe₃O₄ NPs (C) T₁-weighted MRI signals of the tumors at 0, 1, 2, 3, 4, 8, 12, and 24 h after administration of Gd-MFe₃O₄ NPs. Values are expressed as mean ± SD (n = 5).

Figure 8. (A) Temperature changes in the tumor region under 808 nm laser irradiation at various injection; (B) relative tumor volumes of the 4T1 tumor bearing mice receiving various treatments for 14 days; (C) tumors excreted after 14-day with various treatments 1–7: saline, NIR, DOX@MFe₃O₄ NPs, DOX, MFe₃O₄ NPs + NIR, DOX@MFe₃O₄ NPs + NIR, DOX@MFe₃O₄ NPs + NIR + M; (D) Photographs of tumor bearing nude mice and the H&E staining of the tumor at 14 days for various groups, scale bar = 100 μm. Values are expressed as mean ± SD (n = 5).

Figure 9. In vivo toxicity tests of Gd-MFe₃O₄ NPs: (A, a–f) mouse serum biochemistry analysis before (0d, control) and after injection of NPs for 1, 7, and 21 days. (B) Histological images of the heart, liver, spleen lung, and kidney of healthy mice 1, 7, and 21 days injected with Gd-MFe₃O₄ NPs and control mice. The organs were sectioned and stained with hematoxylin and eosin (H&E) and observed under a light microscope, scale bar = 100 μm.