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CoII Complexes as Liposomal CEST Agents
Samira M Abozeid1, Didar Asik1, Gregory E Sokolow1
1Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY, 14260, USA.
Angewandte Chemie (International Ed. in English)
|April 25, 2020
Summary
Paramagnetic cobalt(II) macrocyclic complexes were developed as novel liposomal chemical exchange saturation transfer (lipoCEST) agents. These agents show promise for advanced imaging applications, with distinct CEST peaks observed depending on their incorporation into liposomes.
Area of Science:
- Coordination Chemistry
- Biomedical Imaging
- Materials Science
Background:
- Chemical Exchange Saturation Transfer (CEST) imaging offers high sensitivity for detecting specific molecules.
- Paramagnetic metal complexes are crucial for developing effective CEST agents.
- Liposomes provide a versatile platform for drug delivery and imaging agent encapsulation.
Purpose of the Study:
- To synthesize and characterize novel paramagnetic cobalt(II) macrocyclic complexes.
- To evaluate their potential as liposomal CEST (lipoCEST) agents.
- To investigate the effect of complex structure and liposome incorporation on CEST signal.
Main Methods:
- Synthesis of three Co(II) macrocyclic complexes with varying pendant groups.
- Characterization using 1H NMR spectroscopy and X-ray crystallography.
- Incorporation of complexes into liposomes and evaluation of lipoCEST properties.
Main Results:
- Two isomers of [Co(L1)]2+ were identified, with distinct configurations.
- [Co(L1)]2+ exhibited a significant paramagnetic-induced water proton shift, comparable to LnIII agents.
- Incorporation into liposomes yielded distinct CEST peaks at 3.5 ppm ([Co(L1)]2+) and -13 ppm ([Co(L3)]2+).
Conclusions:
- Paramagnetic Co(II) macrocyclic complexes are feasible as lipoCEST agents.
- Complex structure and liposome localization influence CEST signal characteristics.
- These findings open avenues for developing new contrast agents for MRI.
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