Typologie d'actualités: Group Metal complexes and MRI

In this work, in collaboration with chemists from the Institut de Chimie de Strasbourg (CNRS/Université de Strasbourg), we have designed and studied a smart MRI probe; which is switched on in the presence of copper. The design of such probes is a real challenge as free Cu(II) in vivo is present in very low quantities, typically lower than Zn(II), another physiological cation. It is therefore of prime importance to conceive probes with a maximal turn on response in the presence of Cu(II), and an excellent selectivity towards Zn(II). The probes are typically composed of an MRI active site, a linker and a Cu(II) binding site. The use of small complexing units for Cu(II) binding makes it very difficult to obtain a good selectivity. Here, we have used a bioinspired approach where the Cu(II) binding site is based on the ATCUN motif, a small peptide that binds Cu(II) in the blood. Thanks to this design, the probe displays an unprecedented turn on response, and importantly an excellent selectivity for Cu(II) vs Zn(II). Phantom MRI images obtained closed to physiological conditions show a bright contrast, illustrating the potential of such probes.

Reference :
A Bioinspired Cu2+-Responsive Magnetic Resonance Imaging Contrast Agent with Unprecedented Turn-On Response and Selectivity
Katharina Zimmeter, Agnès Pallier, Bertrand Vileno, Martina Sanadar, Frédéric Szeremeta, Carlos Platas-Iglesias, Peter Faller, Célia S. Bonnet and Angélique Sour
Inorganic Chemistry - Vol 63 - Issue 49 - 23067−23076

Today, magnetic resonance imaging (MRI) is based on the detection of water protons (¹H) in tissues. MRI of ¹⁹F fluorine offers complementary advantages, but its use is hampered by a lack of suitable imaging agents, soluble in water and easily detectable. In order to improve the sensitivity of detecting ¹⁹F MRI signals, a CBM team used Mn²⁺ ions to form complexes with small fluorinated molecules. Unlike currently used nanoparticles, these small molecular probes have well-defined chemical structures and better biocompatibility and water solubility. Finally, thanks to the paramagnetism of manganese(II), they generate a strong signal in MRI. In addition, these fluorinated contrast agents are also active in proton MRI, allowing proton and fluorine MRI images to be superimposed for precise anatomical mapping.

This advance, published in Angewandte Chemie International Edition, opens new horizons in fluorine MRI. It was reported by CNRS Chimie on its website.

Reference :
Small, Fluorinated Mn²⁺ Chelate as an Efficient ¹H and ¹⁹F MRI Probe
Éva Tóth, Zoltán Garda, Frédéric Szeremeta, Océane Quin, Enikő Molnár, Balázs Váradi, Rudy Clémençon, Sandra Même, Chantal Pichon and Gyula Tircsó
Angewandte Chemie International Edition, 2024
DOI: 10.1002/anie.202410998