Reticular Chemistry of the Fcu‐Type Gd(III)‐Doped Metal–Organic Framework for T1‐Weighted Magnetic Resonance Imaging

Abstract

AbstractNanoscale metal–organic frameworks (nanoMOFs) are emerging as an important class of nanomaterials for the systematical investigation of biomedically relevant structure‐property relationship (SPR) due to their highly tailorable features. In this work, the reticular chemistry approach is shown to explore the SPR of a fcu‐type Zr(IV)‐nanoMOF for T1‐weighted magnetic resonance imaging (MRI). Isoreticular replacement of the eight‐coordinated square‐antiprismatic Zr(IV) by nine‐coordinated Gd(III) brings a stoichiometric water capped on the square‐antiprismatic site, enabling the relaxation transfer in the inner‐sphere, giving the r1 value of 4.55 mM−1·s−1 at the doping ratio of Gd : Zr = 1 : 1. Then, these isoreticular engineering studies provide feasible ways to facilitate the relaxation transfer in the second‐ and outer‐sphere of the Gd(III)‐doped Zr‐oxo cluster for the relaxation respectively. Finally, these in vitro and in vivo MRI studies revealed that the Gd(III)‐doped Zr‐oxo cluster aggregated underlying the fcu‐type framework surpasses its discrete molecular cluster for MRI. These results demonstrated that there is plenty of room inside MOFs for T1‐weighted MRI by reticular chemistry.