Figure 5.

(A) Schematic diagram of the synthesis of Fe-VS₂ NSs. (B) Comparative T₁-weighted MR grayscale images of 4T1 tumor-bearing mice before and after intravenous injection of Fe-VS₂-PEG NSs. The red circles highlight the tumor sites. (C) Qualitative analysis of MR intensity showed in B. (D) T₁-weighted magnetic resonance image and r₁ of Fe-VS₂-PEG solutions at different molar concentrations of V. (E) In vivo T₂-MRI of tumor-bearing mice by intravenous injection of UPF or UPFB at different time intervals. Mice were imaged on a 1.2 T MRI scanner (Shanghai, China) for different periods. Tumor sites are marked with red ellipses. (F) Biodistribution of Zr (% injected dose (ID) of Zr per gram of tissues) in major tissues and tumors at different times after injection of UPFB. (H) Fe (% injected dose (ID) of Fe per gram of tissues) content in major tissues and tumors at different times after UPFB injection. (G) Blood circulation profile after intravenous injection of UPFB (n = 5). The half-time (t_1/2) was calculated to be ≈3.381 h. (I) T₁ relaxation rate (1/T₁) of mZMD NCs measured using the concentration of Mn²⁺ (inset: MR images of different concentrations of mZMD NCs in PBS (pH 6.5). Notes: (A–D) Adapted with permission from Ref. [83]. Copyright 2020, American Chemical Society. (E–H) Adapted with permission from Ref. [84]. Copyright 2021, American Chemical Society. (I) Adapted with permission from Ref. [91]. Copyright 2022 Wiley-VCH GmbH.