1.41 t minispec mq 60 nmr analyzer

The longitudinal and transverse relaxation times were determined using a 1.41 T minispec mq 60 NMR Analyzer (Bruker Optik GmbH, Ettlingen, Germany) at 37°C. The relaxivity values of r₁ and r₂ were calculated by fitting the 1/T₁ and 1/T₂ relaxation time (s⁻¹) versus Fe³⁺ concentration (mM) curves. The in vitro MR images of BSA·SPIONs were obtained using a head coil of Siemens MRI system (MAGNETOM Verio; Siemens Healthcare, Munich, Germany). The measurement conditions were as follows: T₂-weighted sequence, multislice spin echo, repitition time/echo time (TR/TE) =4,800/80 ms, matrix acquisition =134 × 192, number of excitations (NEX) =3, field of view (FOV) =63 mm × 63 mm, FOV phase of 100%, thickness =2.5 mm, 3 T, 25°C.

The longitudinal (T1) and transverse (T2) relaxation times of Gd-Au-NC-GPC-1 were evaluated by using a 1.41 T minispec mq60 NMR Analyzer (Bruker Optik GmbH, Ettlingen, Germany) at 37°C. Relaxivity values of r1 and r2 were calculated by fitting the 1/T1 and 1/T2 relaxation time (s⁻¹) versus the Gd concentration (mM) curves.
For in vitro MRI, COLO-357 and 293T cells (2×10⁶) were treated with various concentrations of Gd-Au-NC-GPC-1 at 37°C for 2 hours. The cells were then washed 3 times with PBS and harvested by trypsinization for 3 minutes. After centrifugation at 1,000 rpm for 5 minutes, the cells were resuspended in 20 μL PBS in an Eppendorf Tube^® (Axygen, CA, USA). Magnetic resonance images were acquired using a 3.0 T MAGNETOM Skyra MRI scanner (Siemens, Erlangen, Germany) using T1-weighted sequence (Mapping, repetition time/echo time [TR/TE] =6.83/2.26 ms, thickness =2 mm).

The morphology of the material was observed by transmission electron microscopy using a JEM-2100F electron microscope (JEOL Ltd., Tokyo, Japan), and its hydrodynamic diameter was measured by nanoparticle size analyzer (NanoZS90). The stability test of A-MFS can be found in the Supplementary Materials. The longitudinal (T1) and transverse (T2) relaxation times of A-MFS were measured with a 1.41 T minispec mq 60 NMR Analyzer (Bruker, Karlsruhe, Germany) at 37°C. Relaxivity values of r1 and r2 were calculated by fitting the 1/T1 and 1/T2 relaxation time (s⁻¹) versus Fe concentration (mM) curves. X-ray photoelectron spectroscopy was used to detect chemical elements of A-MFS.