| Abstract
| - New amphiphilic molecules containing a bioactive peptide or a claw moiety have been preparedin order to obtain mixed micelles as target-specific contrast agents in magnetic resonance imaging. Thefirst molecule, C18H37CONH(AdOO)2-G-CCK8 (C18CCK8), contains a C18 hydrophobic moiety bound tothe C-terminal cholecystokinin octapeptide amide (CCK 26−33 or CCK8). The second amphiphiliccompound, C18H37CONHLys(DTPAGlu)CONH2 (C18DTPAGlu) or its gadolinium complex, (C18DTPAGlu(Gd)), contains the same C18 hydrophobic moiety bound, through a lysine residue, to the DTPAGlu chelatingagent. The mixed aggregates as well as the pure C18DTPAGlu aggregate, in the presence and absenceof Gd, have been fully characterized by surface tension measurements, FT-PGSE-NMR, fluorescencequenching, and small-angle neutron scattering measurements. The structural characterization of the mixedaggregates C18DTPAGlu(Gd)−C18CCK8 indicates a spherical arrangement of the micelles with an externalshell of ∼21 Å and an inner core of ∼20 Å. Both the DTPAGlu(Gd) complexes and the CCK8 peptidespoint toward the external surface. The measured values for relaxivity in saline medium at 20 MHz protonLarmor frequency and 25 °C are 18.7 mM-1 s-1. These values show a large enhancement in comparisonwith the isolated DTPAGlu(Gd) complex.
|
