Aryl‐Phosphonate Lanthanide Complexes and Their Fluorinated Derivatives: Investigation of Their Unusual Relaxometric Behavior and Potential Application as Dual Frequency 1H/19F MRI Probes |
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| Authors: | Dr. Matteo P. Placidi Prof. Dr. Mauro Botta Dr. Ferenc K. Kálmán Dr. Gisela E. Hagberg Dr. Zsolt Baranyai Andreas Krenzer Alexandria K. Rogerson Prof. Dr. Imre Tóth Prof. Dr. Nikos K. Logothetis Priv.‐Doz. Dr. Goran Angelovski |
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| Affiliation: | 1. Department for Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, 72076 Tuebingen (Germany);2. Dipartimento di Scienze e Innovazione Tecnologica, University of Piemonte Orientale “Amedeo Avogadro”, 15121 Alessandria (Italy);3. Department of Inorganic and Analytical Chemistry, University of Debrecen, 4010 Debrecen (Hungary);4. Biomedical Magnetic Resonance, Department of Radiology, Tuebingen University Hospital, 72076 Tuebingen (Germany);5. Department of Chemistry, Faculty of Science, University of Tuebingen, 72076 Tuebingen (Germany);6. The School of Chemistry, University of Manchester, Manchester M13?9PL (UK);7. Department of Imaging Science and Biomedical Engineering, University of Manchester, Manchester M13?9PT (UK) |
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| Abstract: | A series of low molecular weight lanthanide complexes were developed that have high 1H longitudinal relaxivities (r1) and the potential to be used as dual frequency 1H and 19F MR probes. Their behavior was investigated in more detail through relaxometry, pH‐potentiometry, luminescence, and multinuclear NMR spectroscopy. Fitting of the 1H NMRD and 17O NMR profiles demonstrated a very short water residence lifetime (<10 ns) and an appreciable second sphere effect. At lower field strengths (20 MHz), two of the complexes displayed a peak in r1 (21.7 and 16.3 mM ?1 s?1) caused by an agglomeration, that can be disrupted through the addition of phosphate anions. NMR spectroscopy revealed that at least two species are present in solution interconverting through an intramolecular binding process. Two complexes provided a suitable signal in 19F NMR spectroscopy and through the selection of optimized imaging parameters, phantom images were obtained in a MRI scanner at concentrations as low as 1 mM . The developed probes could be visualized through both 1H and 19F MRI, showing their capability to function as dual frequency MRI contrast agents. |
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| Keywords: | fluorine gadolinium imaging agents NMR spectroscopy relaxivity |
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