Abstract
Gadolinium-based contrast agents (GBCAs) are the gold standard as MRI probes but are nowadays facing medical limitations and environmental concerns. To address these issues, novel strategies focus on the optimization of Gd(III)-based probes. One promising approach involves incorporating Gd(III) into nanoparticles, particularly coordination polymers, which offer improved relaxivity. In this study, we explore the self-assembly of Gd(III) ions with ascorbate ligand, forming extended coordination polymer architectures. Our investigation focuses on understanding the impact of nanoparticles' growth and aggregation on their relaxivity properties. Notably, the controlled aggregation process leads to a different distribution of the Gd(III) in the surface and in the bulk of the nanoparticles, mainly responsible for their longitudinal relaxivity. Additionally, the introduction of Eu(III) into the network enables the development of a dual-modal probe with paramagnetic and optical features.