MRI-based characterization of multifunctional PNP. (A–C) MRI phantom images of Gd-chelating PNP, which were either empty or loaded with cargo (DiI), demonstrating that the cargo affects the T1 and T2 signal, while it leaves the T2* signal unaffected ([Gd], high = 50 nM, low = 20 nM; [DiI], – = 0 nM, + = 5 nM, ++ = 10 nM. Values were averaged over the entire well). (D) Diffusion-weighted MRI identified that the cargo affected the diffusion of water within the PNP (ADC: apparent diffusion coefficient; [Gd] = 50 nM for all wells). (E) The effect on ADC correlated with the changes in T1 and T2 (PNP: empty PNP without both Gd and DiI). Means ± SEM.