title: New paramagnetic supramolecular adducts for MRI applications based on non-covalent interactions between Gd(III)-complexes and beta- or gamma-cyclodextrin units anchored to chitosan.
abstract: Gd(III) complexes are used as magnetic resonance imaging (MRI) contrast agents because they greatly enhance the relaxation rate of water protons of tissues in which they distribute, an effect that is much more marked if the paramagnetic complex is part of a macromolecular system. Furthermore applications in molecular imaging, require that as many units of contrast agent as possible be directed to the site of interest. To this end we synthesised a polymer made of chitosan functionalized with beta- and gamma-cyclodextrins (CDs) that is able to form high-affinity adducts with suitably functionalized Gd(III) complexes. beta- and gamma-CDs were first treated with maleic anhydride to afford 6-monosubstituted derivatives that reacted regioselectively with the amino groups of chitosan. Reaction times and yields were markedly improved by carrying out these reactions under high-intensity ultrasound or microwave irradiation. Compared to the CD monomers, beta- and gamma-CD-chitosan adducts show large increases both in terms of their binding affinity towards Gd(III) complexes and in relaxivity values and they appear promising carriers for the in vivo vehiculation of Gd(III) complexes.
authors.affiliation: Dipartimento di Chimica, IFM, Università di Torino, via Giuria 7, 10125 Torino, Italy. silvio.aime@unito.it
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
authors.forename: Eliana
authors.initials: E
authors.lastname: Gianolio
authors.forename: Fulvio
authors.initials: F
authors.lastname: Uggeri
authors.forename: Silvia
authors.initials: S
authors.lastname: Tagliapietra
authors.forename: Alessandro
authors.initials: A
authors.lastname: Barge
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cravotto
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D047392:beta-Cyclodextrins / Q000737:chemistry*; D047408:gamma-Cyclodextrins / Q000737:chemistry*
chemical_list: D047392:beta-Cyclodextrins; D047408:gamma-Cyclodextrins; D048271:Chitosan; D005682:Gadolinium; C031215:betadex