RESUMEN
Cyclodextrins (CDs), a class of cyclic oligosaccharides formed by α-(1,4) linked glucopyranose units, were functionalized with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) radicals to prepare water soluble supramolecular organic radical contrast agents (ORCAs) for the inâ vivo detection of glioma tumor in animal models. A first set of molecules (CDn1, n=6,7,8 is the number of both TEMPO and glucopyranose units) was studied by superconducting quantum interference devices (SQUID) magnetometry in order to define the role of the CD macrocycle on the effective magnetic moment (µeff ). The µeff value increased from 3.982â µB (CD61) to 4.522â µB (CD81) but was limited by intramolecular antiferromagnetic (AF) interactions. A set of water-soluble ORCAs (CDn8, n=6,7,8) was prepared by a sequence of thiol-ene and Cu(I)-catalyzed alkyne-azide "click" reactions. Their 1 H water relaxivities r1 of these ORCAs were between 0.739â mM-1 s-1 (CD68) to 1.047â mM-1 s-1 (CD88) in D2 O/H2 O 9 : 1 (v : v) at 300â K. One of them (CD78) was tested on glioma-bearing rats with reduced side effects and good relaxivity inâ vivo.