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Unprecedented Relaxivity Gap in pH-Responsive FeIII-Based MRI Probes |
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| Authors: | Dr Jeremy Salaam Dr Thibault Fogeron Dr Guillaume Pilet Dr Radu Bolbos Dr Christophe Bucher Dr Lhoussain Khrouz Prof Dr Jens Hasserodt |
| Institution: | 1. Laboratoire de Chimie, UMR CNRS/ENSL 5182, Université de Lyon—ENS de Lyon, 46 allee d'Italie, Lyon, France
These authors contributed equally to this work.;2. Laboratoire des Multimatériaux et Interfaces, UMR CNRS/UCBL 5615, Université de Lyon—Université Claude Bernard Lyon 1, DOUA, Villeurbanne, France;3. Dpt. Animage, CERMEP-Imagerie du Vivant, 59 Blvd Pinel, 69677 Bron, France;4. Laboratoire de Chimie, UMR CNRS/ENSL 5182, Université de Lyon—ENS de Lyon, 46 allee d'Italie, Lyon, France |
| Abstract: | Two mononuclear ferric complexes are reported that respond to a pH change with a 27- and 71-fold jump, respectively, in their capacity to accelerate the longitudinal relaxation rate of water-hydrogen nuclei, and this starting from a negligible base value of only 0.06. This unprecedented performance bodes well for tackling the sensitivity issues hampering the development of Molecular MRI. The two chelates also excel in the fully reversible and fatigue-less nature of this phenomenon. The structural reasons for this performance reside in the macrocyclic nature of the hexa-dentate ligand, as well as the presence of a single pendant arm displaying a five-membered lactam or carbamate which show (perturbed) pKa values of 3.5 in the context of this N6 N5O1 coordination motif. |
| Keywords: | Detection Sensitivity Iron(III) Chelates Molecular MRI pH-Responsive Molecular Probes Relaxivity |