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Intramolecular Hydrogen Bonding Restricts Gd-Aqua-Ligand Dynamics
Eszter Boros1, Raja Srinivas2, Hee-Kyung Kim1
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Suite 2301, Charlestown, MA, 02129, USA.
Angewandte Chemie (International Ed. in English)
|April 12, 2017
Summary
An intramolecular hydrogen bond can limit water ligand rotation, enhancing relaxivity for gadolinium (Gd) contrast agents. This strategy boosts magnetic resonance imaging contrast efficiency.
Area of Science:
- Inorganic Chemistry
- Materials Science
- Biomedical Imaging
Background:
- Water ligands on metal complexes can rotate rapidly, reducing their effectiveness as contrast agents.
- Relaxivity, a key measure of contrast agent efficiency, is diminished by rapid water ligand motion.
Purpose of the Study:
- To investigate if intramolecular hydrogen bonding can reduce water ligand rotation.
- To enhance the relaxivity of gadolinium (Gd) complexes for improved MRI contrast.
Main Methods:
- Designed and synthesized four Gd complexes with intramolecular hydrogen bond donors.
- Utilized molecular modeling and molecular dynamics simulations to study complex behavior.
- Measured relaxivity of the designed complexes and compared them to controls.
Main Results:
- Gd complexes with intramolecular H-bonds exhibited significantly higher relaxivity.
- Molecular dynamics confirmed the formation of stable intramolecular H-bonds.
- Ruled out alternative explanations for the observed increase in relaxivity.
Conclusions:
- Intramolecular hydrogen bonding is an effective strategy to decrease water ligand rotational motion.
- This approach successfully increases the relaxivity of Gd-based MRI contrast agents.
- The findings offer a new avenue for designing more efficient contrast agents.