Get access

Redox- and Hypoxia-Responsive MRI Contrast Agents

Authors

  • Quyen N. Do,

    1. Department of Chemistry, The University of Texas at Dallas, 800 West Campbell, BE26, Richardson, TX 75080 (USA)
    Search for more papers by this author
  • Dr. James S. Ratnakar,

    1. Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390 (USA)
    Search for more papers by this author
  • Dr. Zoltán Kovács,

    1. Department of Chemistry, The University of Texas at Dallas, 800 West Campbell, BE26, Richardson, TX 75080 (USA)
    2. Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390 (USA)
    Search for more papers by this author
  • Prof. A. Dean Sherry

    Corresponding author
    1. Department of Chemistry, The University of Texas at Dallas, 800 West Campbell, BE26, Richardson, TX 75080 (USA)
    2. Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390 (USA)
    • Department of Chemistry, The University of Texas at Dallas, 800 West Campbell, BE26, Richardson, TX 75080 (USA)===

    Search for more papers by this author

Abstract

The development of responsive or “smart” magnetic resonance imaging (MRI) contrast agents that can report specific biomarker or biological events has been the focus of MRI contrast agent research over the past 20 years. Among various biological hallmarks of interest, tissue redox and hypoxia are particularly important owing to their roles in disease states and metabolic consequences. Herein we review the development of redox-/hypoxia-sensitive T1 shortening and paramagnetic chemical exchange saturation transfer (PARACEST) MRI contrast agents. Traditionally, the relaxivity of redox-sensitive Gd3+-based complexes is modulated through changes in the ligand structure or molecular rotation, while PARACEST sensors exploit the sensitivity of the metal-bound water exchange rate to electronic effects of the ligand-pendant arms and alterations in the coordination geometry. Newer designs involve complexes of redox-active metal ions in which the oxidation states have different magnetic properties. The challenges of translating redox- and hypoxia-sensitive agents in vivo are also addressed.

Ancillary