Magnetom trio tim mri spectrometer

The T2-weighted MRI of the mice were performed with a clinical Magnetom Trio Tim MRI spectrometer (3.0 Tesla, Siemens Prisma, Germany) using optimized sequences of 3000 ms repetition time, 80 ms echo time, 1.0 mm slice thickness, 1.0 mm slice space thickness and 30 × 96 mm field of view. Prior to the SPION injection, MRI was first performed on all mice as the baseline references. SPION solutions including PDL-SPION, C-pHLIP-SPION and N-pHLIP-SPION (100 μL each) were then intravenously injected at 5 mg Fe per kg body weight (3 mice per group). MRI was performed at 0, 2, 4 and 24 h post iv injection. The resulting MR images were processed with provided Syngo Fastview software (Siemens, Germany).

Three types of SPIO nanoclusters were prepared with PDL, C- and N-terminus linked pHLIP PDL polymers with the hydrodynamic diameter size around 70 nm as PDL-SPION, C-pHLIP-SPION and N-pHLIP-SPION, respectively. Typically, the polymer solution in PBS (50 μg mL⁻¹ for PDL, 150 μg mL⁻¹ for C-pHLIP-PDL or 100 μg mL⁻¹ for N-PDL-pHLIP) was slowly added to an SPIO solution (10 mg mL⁻¹ in PBS at 8.0) at 1 : 1 volume ratio under sonication and then equilibrated at room temperature for 20 h to afford the desired nanoclusters. The hydrodynamic size and zeta-potential of the nanoclusters were determined with a Nano-ZS90 particle analyzer (Malvern, United Kingdom) in PBS. The transmission electron microscopic images were obtained with a Hitachi HT-7700 transmission electron microscope (Tokyo, Japan) using uranyl acetate staining. The stability of SPION was assessed in PBS containing 10% FBS over 24 h at 37 °C with the Nano-ZS90 particle analyzer. The relaxivity (R₂) of assembled nanoclusters was obtained as the slope of a series of SPION concentrations over the 1/T2 that was determined with a clinical Magnetom Trio Tim MRI spectrometer (3.0 Tesla, Siemens Prisma, Germany) as reported.^{35 (link)}