Cu 2+ -Complex of hydrophilic nitrogen-rich polymer dots applied as a new MRI contrast agent.

We report on a novel Cu2+ -complex of nitrogen-rich polymer dots for magnetic resonance imaging (MRI). The N-rich polymer dots are prepared from N-vinyl imidazole (VIm) by a one-pot hydrothermal synthesis at 220 °C (24 h) and used later on to fabricate a Cu2+ -PVIm dot complex via efficient incorporation of Cu2+ into aqueous medium. The obtained Cu2+ -PVIm dot complexes display relaxivity (r1 = 1.05 mM-1 s-1 ) two times higher than Cu2+ in aqueous solution (r1 = 0.43 mM-1 s-1 ) and three times higher than Cu2+ in aqueous solution coordinated with VIm monomers (r1 = 0.32 mM-1 s-1 ), which show a remarkable contrast enhancement for T1 -weighted MRI while efficiently labeling MCF-7 cells and other biomedical applications.