4.7 t small animal scanner

To detect Mn₃O₄ accumulation in tumors, in vivo T₁-weighted MR imaging was performed at 6 h post-injection after intravenous injection of 400 μL NOTA-Mn₃O₄@PEG-TRC105 with a Mn concentration of 1.04 mM. Meanwhile, a blocking study was also conducted through injection of 1 mg of TRC105 before NOTA-Mn₃O₄@PEG-TRC105 administration and subsequent MRI imaging at 6 h p.i. using a 4.7 T small animal scanner (Agilent Technologies, Santa Clara, CA) with the following parameters: TR = 500 ms; TE = 12 ms; flip angle = 120°; FOV = 40 mm × 40 mm; matrix = 256 × 256; NEX = 8; slice thickness = 1 mm for axial images.

The size and morphology of Mn₃O₄ NPs were determined using a JEOL JEM-2100 transmission electron microscope (TEM). X-ray diffraction (XRD) measurements were conducted on a Bruker D4 diffractometer. The surface zeta potential and hydrodynamic size were measured using a Malvern Zetasizer Nano ZS. The T₁-relaxivities and T₁ images were obtained with a conventional spin echo acquisition (repetition time, TR, 1000 ms) with echo time, TE, of 50 ms, and a section thickness of 1 mm in a 4.7 T small animal scanner (Agilent Technologies, Santa Clara, CA). Relaxivity values of r₁ were calculated through curve fitting of 1/T₁ (s⁻¹) versus the manganese concentration (mM). The concentration of Mn was determined by ICP-AES (VISTAMPXICP Varian, USA).