High relaxivity polymeric MRI contrast agents: design, synthesis and polymerisation of Gd complexes

We report a new synthetic strategy for the preparation of high relaxivity macromolecular MRI contrast agents. Five gadolinium(III) complex-es bearing either one or two polymerisable methacrylamide groups were designed and synthesised, serving as monomers, crosslinkers or chain transfer agent respectively, to generate water-soluble copolymers using RAFT polymerisation. Using this approach, polymeric contrast agents (CAs) were synthesised with different architectures, including linear, hyperbranched polymers and gels. The relaxivities of the polymer CAs were determined by NMR relaxometry.