4.

(A) In vivo T1 MR imaging and analysis of mice after intravenous injection of 4.8 nm GdIO@ZDS nanoparticles as contrast agents. a, b: MR images of mice after tail vein injection of 4.8 nm GdIO@ZDS nanoparticles (2.0 mg/kg) at 0, 10, 30, and 60 min, respectively. Blue arrows show the heart, red dot circles show the bladder, and the red dashed squares indicate the kidney. c: Quantification of signal changes (SNR ratio) in the heart, bladder, and kidney at different time points after administration ( n=3). Reproduced with permission from Ref. 41. Copyright 2013 American Chemical Society. (B) a-d: Four-modal imaging of the focused tumor from the tumor-bearing nude mouse 1 h after IV injection of NaLuF ₄: Yb, Tm@NaGdF ₄ ( ¹⁵³Sm). a: In vivo UCL. b: X-ray CT. c: SPECT. d: MR images of the tumor. e: UCL confocal image of the paraffin section of tumor tissue. (f) Schematic illustration of tumor angiogenesis imaging using NaLuF ₄:Yb,Tm@NaGdF ₄ ( ¹⁵³Sm) as the probe. Reproduced with permission from Ref. 44. Copyright 2013 American Chemical Society.