Fig. 5: SSM-PEG (PEG-modified SPIO@SiO₂@MnO₂) for in vivo MRI of 4T1 xenograft tumor-bearing mice.

a T₁ and T₂ Map, b R₁, and c R₂ at the tumor site of the 4T1-bearing mice. The I.V. injections of SSM-PEG and MnO₂-PEG were given a dosage of 5 mg/kg, and the MRI diagnosis was performed at different time points at 0, 1, 6, and 12 h post the injection. T₁ and T₂ Map are representative data from three mice samples. R₁ and R₂ Data are presented as mean ± SD from three independent mice samples. d Illustration of the Dual-contrast-Enhanced Subtraction Imaging (DESI) procedures; T₁ and T₂ dual-modal MRI images were processed by DESI method of the tumor-bearing mice at 12 h after the injection of e SSM-PEG, f MnO₂-PEG, and g SPIO-PEG. Representative data are shown from three mice samples. h The tumor-to-normal tissue signal ratios (TNRs) quantified from the DESI processed images in e–g. Data are presented as mean ± SD from three independent mice samples. i Prussian blue stain and (j) and (k) TEM images of the tumor slices from the mice receiving the injection of SSM-PEG. Representative data are shown from three mice samples. The two-tailed Student’s t-test is employed for the statistical analysis. *P < 0.05; **P < 0.01; ***P < 0.001. Source data are provided as a Source Data file.