Minispec 60

The measurements of longitudinal T₁ and transversal T₂ relaxation times of IO@STMS and IO@WLMS NPs were acquired with a Bruker Minispec 60 (Karlsruhe, Germany) working at a Larmor frequency of 60 MHz (1.41 T) at 37 °C. The longitudinal relaxivity r₁ and transverse relaxivity r₂ values were calculated according to the general equation of relaxivity: R = R₀ + r × [Fe in IO@SiO₂] where R is the relaxation rate (1/T) in the presence of the core-shell IO@SiO₂ nanoparticles, R₀ the relaxation rate of the aqueous medium (in the absence of the NPs) and r the relaxivity value of the core-shell IO@SiO₂.

The longitudinal T1 and transverse T2 relaxation times of the samples were measured by using a Bruker Minispec 60 (Karlsruhe, Germany) apparatus working at 37°C, at a field of 1.41 T corresponding to a Larmor frequency of 60 MHz. The corresponding longitudinal (R1) and transverse (R2) relaxivities were calculated according to the following expression involving the contrast agent: R = R0 + r × [Fe], where [Fe] is the iron concentration of the samples, R is the relaxation rate (1/T) (in the presence of the particles), R0 is the relaxation rate of the aqueous solution (in the absence of the particles), and r is the fitted relaxivity value.