Chemical Spacer Design for Engineering the Relaxometric Properties of Core–Shell Structured Rare Earth Nanoparticles

Abstract

The development of T1/T2 dual-modality contrast agents for magnetic resonance imaging (MRI) is beneficial for eliminating artifacts. However, T1 and T2 agents in the case of direct contact will interfere with each other, and the intrinsic mechanism remains unclear yet. Gadolinium(III) is widely used as T1 contrast agents, while dysprosium(III) exhibits the strongest magnetic moment among rare earth (RE) elements due to the spin–orbital coupling and can potentially be used as T2 contrast agents. The very similar chemical properties of RE elements allow integration of Gd(III) and Dy(III) within single nanocrystals for investigating the interactions between T1 and T2 components so as to achieve T1/T2 dual-modality contrast agents with optimized performance. Therefore, core–shell–shell structured NaDyF4@NaREF4@NaGdF4:Yb,Er nanocrystals were prepared via a seed-mediated growth approach and Gd(III), Er(III), and Y(III) were chosen to construct NaREF4 spacer layer for mediating the interactions between Dy(III) a...