Polycatechol Nanoparticle MRI Contrast Agents

Amphiphilic triblock copolymers containing Fe III -catecholate complexes formulated as spherical- or cylindrical-shaped micellar nanoparticles ( SMN and CMN , respectively) are described as new T 1 -weighted agents with high relaxivity, low cytotoxicity, and long-term stability in biological fl uids. Relaxivities of both SMN and CMN exceed those of established gadolinium chelates across a wide range of magnetic fi eld strengths. Interestingly, shape-dependent behavior is observed in terms of the particles’ interactions with HeLa cells, with CMN exhibiting enhanced uptake and contrast via magnetic resonance imaging (MRI) compared with SMN . These results suggest that control over soft nanoparticle shape will provide an avenue for optimization of particle-based contrast agents as biodiagnostics. The polycatechol nanoparticles are proposed as suitable for preclinical investigations into their viability as gadolinium-free, safe, and effective imaging agents for MRI contrast enhancement.