Block copolymer-based gadolinium nanoparticles as MRI contrast agents with high T ₁ relaxivity

Aims: To synthesize block copolymer-based gadolinium nanoparticles (Gd-NPs) and evaluate their potential as a new MRI contrast agent. Materials & Methods: The Gd-NPs were developed through coordination of gadolinium chelates into a pentablock copolymer synthesized by two sequential atom transfer radical polymerizations, and evaluated by measuring their T ₁ relaxivity in vitro and imaging their T ₁ contrast in tissue using MRI. Results: Solution and MRI studies demonstrated that these Gd-NPs exhibit remarkably high T ₁ relaxivity on both per particle and per gadolinium ion basis, and can generate a much better MRI contrast compared with gadolinium chelates alone. Conclusion: These novel Gd-NPs may have important applications in magnetic resonance-based medical imaging.