An extracellular MRI polymeric contrast agent that degrades at physiological pH

Eric Schopf, Jagadis Sankaranarayanan, Minnie Chan, Robert Mattrey, Adah Almutairi

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Macromolecular contrast agents have the potential to assist magnetic resonance imaging (MRI) due to their high relaxivity, but are not clinically useful because of toxicity due to poor clearance. We have prepared a biodegradable ketal-based polymer contrast agent which is designed to degrade rapidly at physiological pH by hydrolysis, facilitating renal clearance. In vitro, the agent degraded more rapidly at lower pH, with complete fragmentation after 24 h at pH 7.4. In vitro relaxivity measurements showed a direct correlation between molecular weight and relaxivity. We compared our polymer contrast agent with commercially available Magnevist in vivo by MRI imaging, as well as measuring the Gd concentration in blood. Our results show that our polymer contrast agent gives a higher contrast and intensity in the same organs and areas as Magnevist and is cleared from the blood at a similar rate. We aim to improve our polymer contrast agent design to develop it for use as a MRI contrast agent, and explore its use as a platform for other imaging modalities.

Original languageEnglish (US)
Pages (from-to)1911-1918
Number of pages8
JournalMolecular Pharmaceutics
Issue number7
StatePublished - Jul 2 2012


  • Gd(III) complexes
  • bioresponsive
  • contrast agents
  • extracellular degradation
  • polyketal

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery


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