The synthesis, characterization and manipulation of MRI contrast-agent labeled, functionally diverse polymeric materials is critical for imaging advanced materials in vivo. In order to study these materials in vivo, we developed a novel labelling strategy using a gadolinium-containing MRI contrast agent. MRI offers several advantages over fluorescence imaging, including real-time imaging capabilities, and increased in vivo sensitivity, compared to fluorescent dyes. We synthesized a novel Gd-DOTA modified norbornene monomer, and a Gd-DOTA modified chain-transfer reagent (termination agent), both amendable to ring-opening metathesis polymerization (ROMP). Using ROMP, a small library of polymeric amphiphiles were synthesized and subsequently formulated to form a variety of morphologies in aqueous environment: either spherical micelles, fibril-shaped micelles, or completely dispersed hydrophilic polymers. The different morphologies were found to have differences in contrast-enhancement in vitro. Furthermore, we investigated the in vivo biodistribution of these materials (spheres, fibers, and polymers) in a head-to head study comparing the analogous small-molecule contrast agent (Gd-DOTA). While the polymeric materials behaved similarly to the small-molecule with respect to clearance rate and mode of clearance, the nanoparticles showed significant retention after intraperitoneal injection. We believe formulating more complex (ie targeting) nanomaterials in specific morphologies will play an important role in manipulating the biodistribution and clearance rates of advanced materials.

Synthesis of MRI-contrast agent labeled polymeric nanomaterials and the effect of morphology on in vivo properties

248th National Meeting (2014)

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