Mardi 10 mai à 11h, salle O. Khan
Prof. Janet Morrow, l’Université de Buffalo aux USA (https://arts-sciences.buffalo.edu/chemistry/faculty/faculty-directory/morrow.html)
"Macrocycles, Cages and Liposome-based Cobalt and Iron Complexes as Magnetic Resonance Imaging Probes"
Abstract :
MRI probes or contrast agents contain paramagnetic metal ion complexes that produce contrast through changes in proton relaxation times or water proton shift. Research in our laboratory is focused on transition metal complexes as 1) alternatives to Gd(III) based contrast agents, 2) probes that are responsive to the biological environment and 3) as agents that accumulate in tumors for drug delivery. Macrocyclic ligands are central to our research through modulating the spin and oxidation states of cobalt and iron complexes in aqueous solutions. For example, macrocyclic complexes of high spin Co(II) produce highly shifted water protons and can be loaded into liposomes and/or incorporated into the bilayer to produce chemical exchange saturation transfer (lipoCEST) agents. These liposomal agents are responsive to redox or pH changes in solution as detected by a change in the asymmetry of the z-spectrum. High spin Fe(III) macrocyclic complexes show enhanced water proton T1 relaxation as potential Gd(III) alternatives. Incorporation of Fe(III) complexes into liposomes produces T1 agents for tracking the delivery of intraliposomal contents to murine tumors. Finally Fe(III) centers can be linked together to form self-assembled cages that behave as blood pool agents and accumulate in murine tumor models.