Paramagnetic 19F Relaxation Enhancement in Nickel(II) Complexes of N-Trifluoroethyl Cyclam Derivatives and Cell Labeling for 19F MRI
Language English Country United States Media print
Document type Journal Article
- MeSH
- Coordination Complexes chemical synthesis chemistry pharmacology toxicity MeSH
- Ligands MeSH
- Magnetic Resonance Imaging methods MeSH
- Lactams, Macrocyclic chemical synthesis chemistry pharmacology toxicity MeSH
- Mesenchymal Stem Cells metabolism MeSH
- Molecular Structure MeSH
- Nickel chemistry MeSH
- Rats, Inbred Lew MeSH
- Radiopharmaceuticals chemical synthesis chemistry pharmacology toxicity MeSH
- Fluorine Radioisotopes MeSH
- Drug Stability MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Coordination Complexes MeSH
- Ligands MeSH
- Lactams, Macrocyclic MeSH
- Nickel MeSH
- Radiopharmaceuticals MeSH
- Fluorine Radioisotopes MeSH
1,8-Bis(2,2,2-trifluoroethyl)cyclam (te2f) derivatives with two coordinating pendant arms involving methylenecarboxylic acid (H2te2f2a), methylenephosphonic acid (H4te2f2p), (2-pyridyl)methyl (te2f2py), and 2-aminoethyl arms (te2f2ae) in 4,11-positions were prepared, and their nickel(II) complexes were investigated as possible 19F MR tracers. The solid-state structures of several synthetic intermediates, ligands, and all complexes were confirmed by X-ray diffraction analysis. The average Ni···F distances were determined to be about 5.2 Å. All complexes exhibit a trans-III cyclam conformation with pendant arms bound in the apical positions. Kinetic inertness of the complexes is increased in the ligand order te2f2ae ≪ te2f < te2f2py ≈ H4te2f2p ≪ H2te2f2a. The [Ni(te2f2a)] complex is the most kinetically inert Ni(II) complex reported so far. Paramagnetic divalent nickel caused a shortening of 19F NMR relaxation time down to the millisecond range. Solubility, stability, and cell toxicity were only satisfactory for the [Ni(te2f2p)]2- complex. This complex was visualized by 19F MRI utilizing an ultrashort echo time (UTE) imaging pulse sequence, which led to an increase in sensitivity gain. Mesenchymal stem cells were successfully loaded with the complex (up to 0.925/5.55 pg Ni/F per cell).19F MRI using a UTE pulse sequence provided images with a good signal-to-noise ratio within the measurement time, as short as tens of minutes. The data thus proved a major sensitivity gain in 19F MRI achieved by utilization of the paramagnetic (transition) metal complex as 19F MR tracers coupled with the optimal fast imaging protocol.
References provided by Crossref.org
Fluorine polymer probes for magnetic resonance imaging: quo vadis?
Low-molecular-weight paramagnetic 19F contrast agents for fluorine magnetic resonance imaging
