Controlled Self‐Assembling of Gadolinium Nanoparticles as Smart Molecular Magnetic Resonance Imaging Contrast Agents

Gd smart: MRI contrast agents are presented that are based on a biocompatible condensation reaction. Upon reduction, a gadolinium-containing cell-permeable small-molecule probe condenses into cyclic oligomers that subsequently self-assemble into nanoparticles (NPs) with enhanced relaxivity (by 110 % at 1.5 T and 35 °C, and 104 % in live cells at 0.5 T).